The upgrade project for the LHC injectors is described in detail, highlighting the major improvements implemented in the injector chain. Lessons in technical progress, project management and planning are presented. The performance of the upgraded systems in intensity, average particle flux and beam brightness is described and compared to the upgrade goals and LHC`s original design parameters. The LHC performance with the upgraded injection chain and the luminosity achieved are presented. A future outlook to future developments is given.
An overview of the project status of the future Italian 2.4 GeV 4th generation light source Elettra 2.0 that will replace the existing 3rd generation light source Elettra is presented, including challenges and perspectives in the design and construction of such light sources. Elettra 2.0 will be the ultra-low emittance light source that will provide ultra-high brilliance and coherence and at the same time also aims to provide very short pulses for time resolved experiments. The discussion includes the technical challenges requiring specific R&D studies, for example on injection schemes, high performance magnets, vacuum, diagnostics for stability, feed-backs, harmonic cavities, etc. The upgrade also addresses on the request from the established user community to minimize the duration of beam-time interruption, imposing the need of a careful organization and planning of all the phases of the project, from the removal of the old machine to the installation and successful commissioning of the new one.
LCLS-2 should be completed in 2022, producing first light from its new SC linac. The status of beam commissioning and the performance of the new SC CW linac should be shown in detail. Performance should be compared with the design values and an outlook to further steps should be shown.
The Linear IFMIF Prototype Accelerator (LIPAc) has been constructed in Rokkasho, Japan to demonstrate the validity of the low energy section of an IFMIF deuteron accelerator up to 9 MeV with a beam current of 125 mA in continuous wave (CW) under the joint collaboration between EU and Japan. The short-pulse 125-mA deuteron beam acceleration to 5 MeV was successfully demonstrated in 2019. Now LIPAc is under commissioning toward the CW beam acceleration. The effort to realize the high-current CW beam, e.g. the commissioning of the ion source at high-current, CW and the conditioning of the RFQ cavity at CW, and the result of the beam commissioning campaign will be presented.
Superconducting RF thin film (SRF-TF) technology for RF cavities has only recently began to achieve accelerator field gradients and Q-factors close to that of bulk niobium SRF cavities. These thin films (such as Nb3Sn, NbTiN, Mg2B and multilayer structures) offer the ability to operate at higher temperatures (4.2 K instead of 1.9 K) thereby increasing the operating efficiency of the RF system and also the potential for achieving higher operating gradients (>50 MV/m) thereby reducing the practical accelerator footprint, both of which aiming to help maximise future sustainability. Much more development however is needed to optimise and master the thin film deposition process on RF cavities, as well as to understand the fundamental RF performance of these enhanced films. In order to develop SRF-TF capabilities beyond current limits, there are a number of international collaborations ongoing which will be described, in Europe it is being conducted under the umbrella of the H2020 ARIES and IFAST programmes.
Laser-plasma acceleration is a technique for producing ultra-relativistic electrons that takes advantage of the ability of plasma to carry arbitrarily intense fields. In practice, fields of several hundred GV/m can be produced simply by focusing an ultra-intense laser pulse in a sub-critical plasma [1]. These fields, which are 3 orders of magnitude larger than those produced in conventional plasma accelerators, are nevertheless useless if the field is not maintained over a significant distance or if the accelerated electron beam does not remain trapped in it.
In practice, three phenomena limit the acceleration length in a laser-plasma accelerator: pump depletion, diffraction, and dephasing. Pump depletion, i.e. the laser energy transfer to the plasma wave, and laser diffraction tend to decrease the laser intensity during its propagation down to a level from which it can no more drive a steady plasma wave.
Dephasing originates from the difference in velocity between the electron bunch and the laser, which results in a progressive shift of the electron beam towards a decelerating phase of the electric field.
Here we discuss several approaches for tackling this limitations and increasing the beam energy: the rephasing technique, which extends the effective dephasing length [2], the acceleration in a laser-plasma waveguide, which prevents diffraction [3], and finally a dephasing-less, diffraction-free acceleration scheme that solves all three issues at once [4]. We will also present the first demonstration of the controlled injection of electron beams in a plasma waveguide which has allowed the production of quasi-monoenergetic electron beams at the GeV level. These results remove a major bottleneck to development of high energy plasma accelerators and pave the way to the stable production of high-quality, multi GeV beams [5].
[1] Esarey, E., Schroeder C. B. and Leemans, W. Review Modern Physics 81, 1229–1285, (2009).
[2] Guillaume, E. et al. Physical Review Letter 115, 155002 (2015).
[3] Smartsev, S. et al.Optics Letter 44, 3414–3417 (2019).
[4] Caizergues, C., Smartsev, S., Malka, V., and Thaury C. Nature Photonics 14, 475–479 (2020)
[5] Oubrerie, K. et al. arXiv:2108.03000 (2021)
The European Eupraxia project has recently been included in the ESFRI roadmap. EuPRAXIA is a world-wide first, new kind of compact facility and will be constructed at two European sites. One of the two sites for Eupraxia will be the INFN LNF at Frascati. The facility will be integrated with the already planned 1GeV linear accelerator.
This talk will cover the status of the technical design of the accelerator, general infrastructure plans and future pilot applications in the user community.
Delivering and tailoring beams for wide range of novel applications is a challenging task in single pass accelerator test facilities. This talk will review beam dynamics challenges at single pass accelerator test facilities in Europe (e.g. ARES@DESY, CLARA@STFC, CLEAR@CERN, FLUTE@KIT and PITZ@DESY) to generate, transport and tailor high brightness beams for range of novel applications.
Next generation storage ring light sources will dramatically increase the electron beam brightness, thereby significantly increasing the X-ray brightness for science. Such intense electron beams exhibit numerous collective effects that potentially drive instabilities. Advanced numerical simulation methods are compared with theory and experimental measurements at different machines. One important issue is longitudinal collective beam dynamics with very low synchrotron frequency when higher-harmonic rf systems are used to lengthen the bunch and beam lifetime. Ion effects are also discussed in these very low emittance machines. This paper gives an overview of these and other collective physics, and discusses efforts to predict and mitigate any potentially deleterious effects.
The Fermilab Linac delivers 400 MeV H- beam to the rest of the accelerator chain. We are exploring several machine learning (ML) techniques for automated RF tuning, with an emphasis on time-evolving modeling that can account for parameter drift. Providing stable intensity, energy, and emittance is key since it directly affects downstream machines. To operate high current beam, accelerators must minimize uncontrolled particle loss; this ca be accomplished by minimizing beam longitudinal emittance via RF parameter optimization. However, RF tuning is required daily since the resonance frequency of the accelerating cavities is affected by ambient temperature and humidity variations and thus drifts with time. In addition, the energy and phase space distribution of particles emerging from the ion source are subject to fluctuations. Such drift is not unique to Fermilab, but rather affects most laboratories. Our methods include Bayesian optimization, and RF system surrogate modeling based on diagnostics data from beam loss monitors and beam position monitors. We will present the status of each approach and future plans.
In the commissioning and operational stage of X-ray free-electron lasers (XFELs), it is a challenging problem to efficiently tune the large-scale scientific machines which consist of hundreds and thousands of components. Here we tried to introduce several tuning algorithms to achieve automatic tuning in XFELs and compared the performance. This also paves the way for further development of intelligent online optimization schemes.
Although beam emittance is critical for the performance of high-brightness accelerators, optimization is often time limited as emittance calculations, commonly done via quadrupole scans, are typically slow. Such calculations are a type of multi-point queries, i.e. each query requires multiple secondary measurements. Traditional black-box optimizers such as Bayesian optimization are slow and inefficient when dealing with such objectives as they must acquire the full series of measurements, but return only the emittance, with each query. We propose using Bayesian Algorithm Execution (BAX) to instead query and model individual beam-size measurements. BAX avoids the slow multi-point query on the accelerator by acquiring points through a virtual objective, i.e. calculating the emittance objective from a fast learned model rather than directly from the accelerator. Here, we use BAX to minimize emittance at the Linac Coherent Light Source (LCLS) and the Facility for Advanced Accelerator Experimental Tests II (FACET-II). In simulation, BAX is 20x faster and more robust to noise compared to existing methods. In live LCLS and FACET-II tests, BAX performed the first automated emittance tuning, matching the hand-tuned emittance at FACET-II and achieving a 24% lower emittance at LCLS. Our method represents a conceptual shift for optimizing multi-point queries, and we anticipate that it can be readily adapted to other similar problems commonly found in particle accelerators and beyond.
The Eupraxia@SPARC_LAB project, foreseen a 1GeV Linac based on a X-band booster composed by 16 accelerating structures working at the nominal gradient of 60MV/m. In this framework, an intense activity has started in the last years in order to prove the reliability and functionality of the X-band technology at very high peak power. The main step of this activity has been the implementation of a X-band test station TEX, based on an RF power source capable to deliver 50MW RF pulses that are used for accelerating structures and RF components conditioning and testing. This test facility has been successfully commissioned and entered into operation at the end of 2022. Together with the source commissioning different RF components in X-band, necessary for the Eupraxia Linac, have been developed and will be tested soon at the nominal peak power in the TEX facility. In this article the status and operation of the TEX facility is reported together with a report on the main activities on the X-band technology performed at INFN-LNF.
The 30 MeV IBA-Belgium (Ion Beam Application SA) cyclotron is operated at TENMAK NUKEN for producing medical radioisotopes with three beamlines and a fourth beamline is dedicated for research purposes. The minimum energy of extracted proton beam from cyclotron is 15 MeV .There is no facility in Turkiye for applying ion beam analysis techniques (IBA) currently. These techniques generally require 1-5 MeV proton beam energy. We developed and installed an energy degrader system on the R&D beamline for this purpose. This degrader system is capable of decreasing the energy down to 1 MeV with pA to $\mu$A current levels. A high vacuum irradiation chamber was developed at the end of the beamline. This chamber has ports to install several types of detectors for different IBA techniques. This work includes the description of the setup and preliminary PIXE/PIGE measurements.
Particle accelerators, relevant to LANL’s mission spaces will rely on the use of copper based rf structure for charged particle acceleration. Additively manufactured (AM) copper structures offer the usual well-known advantages in terms of relaxation of physical design (shape) constraints, and thus hold the promise of making complex shaped rf structures. To rapidly demonstrate the potential to additively manufacture accelerator structures with existing technology, a bound metal deposition (BMD) metal 3D printer will be used to build a scaled design and the results of this effort will be presented.
An important part of the new accelerator MESA (Mainz Energy-recovering Superconducting Accelerator) is the beamline connecting the pre-accelerator with the main accelerator. The setup includes a vertical parallel beam offset realized with two dipoles. These are designed in a way, that they can serve as steerer for the main accelerator and will be discussed in this contribution. Furthermore, the beamline contains a horizontal 180°-beam deflection realized with four dipoles. It is also possible to extract the beam to a Mott-polarimeter* and to a separate diagnostic beamline. The layout and the lattice- and particle simulations leading to this will be discussed concerning beam dynamics especially with regard to the high beam currents of 1 mA in cw-mode.
The HEPS (High Energy Photon Source) is a fourth generation photon source. According to the tiny dynamic aperture，we choose on-axis swap-out injection scheme. There are five subsystems in the whole injection and extraction system of the HEPS, and only each of them kicks the beam precisely can the machine works well. In the high energy extraction system，we need four bumpers and one kicker. This article aims to introduce how to design and implement the booster bumper pulser.Depending on the simulation and test，we select IGBT (Insulated Gate Bipolar Transistor) as power device. And using LC resonance circuit to acquire a needed pulse.
Results A prototype has been fulfilled，and the testing results show that the output pulse bottom width is less than 1ms，the peak current is more than 250A, the stability of peak current is less than 0.3%.
This bumper pulser can fully meet the requirements of high energy extraction system.
MINERVA (MYRRHA phase 1) aims at demonstrating the requirements related to the reliability and the fault tolerances of the MYRRHA accelerator-driven system (ADS) by the realization of a superconducting linac for 100 MeV/4 mA proton beams. The design and the performance of the Medium Energy Beam Transfer section (referred to as MEBT-3) of the accelerator are critical for reaching the goals of MINERVA.
The purpose of the MEBT-3 is to fast-switch between a 17 MeV beam coming from one injector to another to ensure a continuous injection of 17 MeV proton beam in the main superconducting linac, in case one of the injectors would fail. The design goals of the MEBT-3 are to reach maximal beam transmission, accurate beam definition for matching the linac and a double achromaticity after the last switching dipole. For the protection of the main linac, a dedicated collimation system consisting of multiple slits was designed and incorporated into the MEBT-3 section.
The expected performance of the MEBT-3 has been studied extensively by beam dynamics simulations in order to reach the desired specifications. The non-accelerating MEBT-3 section includes multiple transverse and longitudinal beam focusing elements, such as magnetic quadrupoles and room temperature re-bunchers. The latest beam dynamics studies for achieving the MEBT-3 design goals will be presented.
This study is motivated by the search for the electric dipole moment (EDM) of elementary particles. The most promising idea in that regard is the “Frozen Spin” concept first proposed by the BNL. This concept, however, requires the building of a brand-new facility devoted to the EDM-search. NICA is not such a facility, hence the need for a modification compatible with the existing optics; one that wouldn’t disrupt the ring’s capability for parallel experiments. Such a modification is the “Quasi-Frozen Spin” idea, realized by adding transport channels, bypassing the ring’s straight sections. Wien-filters are placed in these channels in order to compensate spin-rotations caused by the ring’s arc dipoles, thus making its net spin-transfer matrix unitary. Even though, during its movement along the beam line, the beam’s polarization vector deviates from alignment with the momentum vector, this motion is regular and fits within one beam revolution, allowing for the buildup of the EDM-signal. The present study shows that the “Quasi-Frozen Spin”-specific optics is consistent with the existing NICA lattice and that the modified structure is capable of maintaining a requisite spin-coherence time.
Hefei Advanced Light Facility (HALF) was designed as fourth generation light source based on the diffraction-limited storage ring (DLSR). The pre-research has been completely done, due to the smaller beam dynamic aperture, about 10mm, beam inject could not completed by the traditional bump magnet. We purposed and designed a novel dual-channel kicker, with other two traditional kicker, they were combined the new injection system. The paper presented the principle and layout and the detail of the novel dual-channel.
The performance of positron source in the International Linear Collider (ILC) is critical for the luminosity and therefore the physics output of this planned, future high energy physics machine. In the undulator-based source proposed for the ILC, positrons are produced by generation of electron-positron pairs by an incident high energy photon on a high-Z target material. The amount of positron that can be transported downstream the adjacent accelerator section and finally the interaction point is to a large extent defined by the so-called optical matching device. This beam-optics element matches the phase space of the high-divergence, large-energy-spread positron beam into the acceptance of the accelerating section beam optics. As conventional matching devices like the quarter-wave transformer do not fulfill the stringent requirements of the ILC, a pulsed solenoid was proposed and shown in simulation to outperform other proposed devices. In this contribution we discuss the current status of this pulsed solenoid with respect to positron capture efficiency, cooling, mechanical stability, and other critical performance aspects.
Nowadays, Energy Recovery Linacs (ERLs) became really appealing thanks to their low environmental impact and high sustainability.
ERLs require a special low energy injector, usually named merger. The energy at merger exit is clearly the energy that can’t be recycled in the ERL machine and is the amount dumped at the end. The lower the injection energy is the more efficient is the energy recovery process.
A physiological issue of low energy ERL injection is the presence of space charge in the dispersive section that introduces to dispersion leaks.
Worldwide ad hoc solutions for mergers beamlines design have been studied to address this problem.
Here we present a different approach that allowed us to exploit a standard dogleg to design a very low energy merger for an ERL. This has been made possible thanks to the application of the GIOTTO AI code that optimizes of the optics setting finding a proper achromatic configuration.
Diamond Light Source has been operating in top-up mode for users since late 2008. To date, Diamond’s electron gun has operated in single-bunch mode for multiple-shot top-up of user beam, and multibunch mode for storage ring fill. The uneven bunch-to-bunch charge of the multibunch train is visible in the storage ring and so the fast multibunch fill must be followed by a slower single bunch correction before beam can be given to users. A new pulser has been developed that will generate a flat, fast-rising 500 MHz train of electron bunches from the gun that will enable a uniform fill of the storage ring without single bunch correction. Arbitrary bunch-by-bunch shaping of the train can be used for multibunch fill and top-up of any required fill pattern, thus exploiting the greater charge available in multibunch mode to reduce the number of top-up shots and consequent disturbance to users. Pulser development and results are presented, together with a report of progress towards multibunch top-up.
Polarized helions are part of the Electron Ion Collider physics program. Improving polarization transmission for the injectors is paramount to reach the high polarization requirements for the physics program. In efforts to further optimize transmission of polarized helions in the AGS Booster, quadrupoles throughout the AGS Booster have had their positions adjusted. This reduction in vertical quadrupole alignment deviation results in lower corrector dipole current requirements for utilizing the harmonic correction method for imperfection resonance crossing. These adjustments also improve the matching with the AGS Booster and the NASA Space Radiation Laboratory transport line, and the AGS to Booster transport line.
The nominal Diamond-II storage ring optics have been designed to produce a pseudo twenty-four-fold symmetry by maintaining equal phase advance across the long and standard straights [1]. In this paper, the impact of introducing a high beta section in the injection straight and reducing the ring symmetry to one have been extensively investigated. This solution does not require any additional hardware and so can be switched on or off as required. In this paper we present the optics solution and study the expected performance.
[1] Diamond-II Technical Design Report, (2022).
An MeV ultrafast electron diffraction (MUED) instrument system, such as is located at the Accelerator Test Facility (ATF) of Brookhaven National Laboratory, is a structural characterization technique suited to investigate dynamics in the ultrashort range in a variety of materials via a laser pump method. It is a unique characterization technique especially suitable for highly correlated materials. This technology can be advanced further into a turnkey instrument by using data science and artificial intelligence (AI) mechanisms in conjunction with high-performance computing. This can facilitate automated operation, data acquisition, and real-time or near-real-time processing. The AI-based system controls can provide real-time feedback on the electron beam or provide virtual diagnostics of the beam. Deep learning can be applied to the MUED diffraction patterns to recover valuable information on subtle lattice variations that can lead to a greater understanding of a wide range of material systems. A data-science-enabled MUED facility will also facilitate the application of this technique, expand its user base, and provide a fully automated state-of-the-art instrument. Another beamline enhancement planned is the extension of the beamline sample area to include additional instrumentation for simultaneous measurement of a standard baseline sample. EM modeling of the beamline components facilitates this. Updates on research and development for the MUED instrument are presented.
The accelerator high-power system provides electromagnetic energy to the acceleration structure to establish a high-power acceleration field. In pace with the current intensity development of accelerator beam, heigtening RF system performance is put on a new agenda. Temperature is a momentous parameter of accelerator RF system, which will directly affect the mechanical, electromagnetic and signal stability of high frequency system. Therefore, an optimized water cooling scheme for solid-state power source is designed to obtain the most reliable and convenient cooling system with the least cost. Firstly, the diverter of the overall water cooling system is designed to ensure that each power amplifier module can achieve the same heat dissipation effect when output the same power. Next, the runner of a single power amplifier module is optimized to ensure that the pressure at the plug connector is appropriate. Finally, the power module is designed in the form of water and electricity separation, that is, the way of contact cooling is adopted to increase the maintainability.
The Electron Ion Collider calls for polarized helion and proton on polarized electron collisions. The placement of rotators in the Hadron Storage Ring is asymmetric relative to the interaction region, due to spacial constraints. The rotators must satisfy longitudinally polarized proton and helion beams at the interaction point over a wide range of energies. This paper gives an overview of simulations done with HSR spin rotators.
The High Luminosity Large Hadron Collider (HL-LHC) project foresees the upgrade of a large fraction of primary and secondary collimators of the betatron cleaning system to reduce the collimation impedance. The new collimator design also includes the installation of in-jaw beam position monitors (BPMs) to align the collimators faster and to continuously monitor the beam orbit, ensuring an optimum collimation hierarchy. This upgrade is being done in two stages: 12 of the 22 new collimators were already installed during Long Shutdown 2 (2018-2021), four primary collimators and eight secondary collimators. They have been used in normal operation since the recommissioning in 2022. This paper discusses the experience gained with these BPMs during the recommissioning of the LHC. This includes orbit stability throughout a complete cycle, comparison of alignment with BPMs and the traditional method based on beam loss monitors, as well as interlock strategies.
On and off-momentum transverse dynamics of the next generation diffraction-limited storage rings are in general severely limited by the chromaticity correction. Their restoration using harmonic sextupoles and octupoles therefore represents a crucial step in designing a lattice. Due to complexity of this process, purely numerical methods such as using MOGA tend to be more effective, which however render physical interpretations of the optimization more difficult. As an alternative and complementary approach, description of dynamic apertures using the single resonance approximation in perturbation theory attempted in Ref. 1 is revisited. Several extensions of the previous work are made such as application to higher-orders in perturbation, coupling resonances, inclusion of octupoles, as well as application to off-momentum dynamics. Applied results are presented and discussed.
[1] R. Nagaoka et al., NIM A302 (1991) 9
A lattice of a storage ring for the future plan of UVSOR synchrotron facility, UVSOR-IV, is designed at 1 GeV electron energy. The lattice of 12 compact double achromat cells conducts to an emittance of 4.2 nm at 1 GeV electron energy and 2.3 nm at 750 MeV electron energy in achromat condition, 82.5 m circumference, and six straight sections of 4 m long and six of 1.5 m long. The lattice has the flexibility of beta function and dispersion function at the straight sections which can produce lower emittance in the non-achromatic condition and short bunch length in isochronous condition. The lattice requires strong sextupole magnets to compensate the natural chromaticity. To help deal with the challenge of dynamic aperture associated with strong nonlinearities, we examined optimizing the dynamic aperture with the sextupole arrangement based on the Bayesian method. In the conference, the latest results from the design study will be reported.
After the successful conclusion of Run1 in 2018, the AWAKE experiment is presently undergoing its second phase (Run2), which aims to demonstrate the possibility of producing high quality electron beams for high energy physics applications.
Over the last year, a significant time-investment was made to study proton beam centroid modulation effects in plasma induced by a seeding electron bunch (i.e. hosing). The high beam pointing accuracy needed for the study translated in tighter constraints for the 18 MeV electrons injection line. To address the new requirements, a measurements campaign was dedicated to the characterization and optimization of the beam line. In the first part of this paper, we present the results of the measurements and simulations carried out for the line characterization. The second part focuses on the description of the operational tools developed to address the new beam requirements and performance.
Heavy-ion single event effect (SEE) test facilities are critical in the development of microelectronic components that will be exposed to the ionizing particles present in the hostile environment of space. CHARM High-energy Ions for Micro Electronics Reliability Assurance (CHIMERA) has developed a high-energy ion beam able to scan a wide range of Linear Energy Transfer (LET) at low intensities to study ionization effects on space-bound technology using CERN's Proton Synchrotron (PS). This contribution describes the extraction and transport of low intensity lead ions at multiple energies to the CHARM facility at the East Area of CERN. Measurements of the beam characteristics are compared to simulation and a study to manipulate and homogenise the transverse beam density on the irradiated components is discussed.
The Large Hadron Electron Collider (LHeC) is an option for CERN to construct an energy recovery linear accelerator tangentially to the HL-LHC (High Luminosity
Large Hadron Collider) and would enable deep inelastic scattering collisions between electrons and protons. In this design, one of the proton beams of the
HL-LHC goes into collision with the electron beam, while the second proton beam
is guided around the collision in this interaction point. The e-p interaction is
designed to operate concurrently with p-p collisions in ATLAS, CMS and LHCb.
The interaction region is laid out for alternate e-h and h-h data taking using
a common detector with ALICE, suitable for this novel way of operation. It
therefore requires a highly precise beam optics and orbit for the three beams:
the two proton beams of the HL-LHC, as well as the electron beam from the
energy recovery linac. The highly asymmetric optics and orbits of the two proton beams, allowing concurrent operation of the HL-LHC experiments and e-p
collisions, have been modelled in MADx. The impact of an optimized electron
minibeta insertion, focusing and bending the electrons, on the proton beam
dynamics has been considered.
The electron-positron Future Circular Collider (FCC-ee) foresees stored beam energies up to 20.7 MJ, a value almost two orders of magnitude higher than any previous lepton collider. Considering the intrinsic damage potential of the FCC-ee beams, a halo collimation system is under study to protect the most sensitive equipment from unavoidable losses. Beam dynamics and tracking studies are key aspects to evaluate the cleaning performance of the collimation system, as they help in an iterative process to converge on an optimum performance. The first results of such studies, exploring various configurations of materials and collimator lengths, are presented, including also estimated beam loss distributions around the ring. In addition, an impact parameter scan on the primary collimators is studied to identify the most critical case for the protection of sensitive equipment.
The Electron Storage Ring (ESR) of the Electron-Ion Collider (EIC) will operate with average beam currents of up to 2.5 A, with up to 1,160 bunches, rms bunch lengths as short as ∼ 7 mm, and maximum beam energy of 18 GeV. Accumulating such an intense electron beam with short bunches at high energy is particularly challenging as it results in significant resistive wall heating of the vacuum chamber components and large synchrotron radiation at the arcs. Similarly, the Hadron Storage Ring (HSR) stores an average beam current of 0.69 A in 290 bunches with a 60 mm rms bunch length for the worst-case scenario in terms of resistive wall heating. Both rings demand a detailed analysis to evaluate the impedance and collective effects. This paper provides an update on the beam-induced heating analysis for the EIC vacuum chamber components. To find the thermal distributions over a vacuum component, we first evaluated the resistive wall loss to its individual sections using CST simulations, and then those data for the individual loss are fed into ANSYS simulation. We present the updated beam-induced heating results for the ESR components such as BPM, standard RF shielded bellows, and gate valves, and for the HSR vacuum components including the BPM bellows assembly.
The Insertion Region 2 (IR2) is proposed to accommodate a pre-cooler at injection energy (24 GeV) and a Strong Hadron Cooling facility at top energy (100 GeV and 275 GeV) in the Hadron Storage Ring (HSR) of the Electron-Ion Collider (EIC). This paper summarizes the lattice update in HSR-IR2 to meet the requirement from the pre-cooling and the SHC. The layout has been changed to provide a longer cooling section. The beam optics varies smoothly during ramping from the injection energy to the top energy. It also describes how to enable the vertical cooling for the SHC in IR2.
The proposed REDTOP experiment is a $\eta$/$\eta'$ factory aiming to explore dark matter and physics beyond the Standard Model. The $\eta$ and $\eta'$ mesons are almost unique in the particle universe because of their quantum numbers and the dynamics of their decay are strongly constrained. This effect increases the branching ratio of rare decays which can be studied to probe physics BSM. The integrated eta meson samples collected in earlier experiments have been about ~$10^9$ events, dominated by the WASA at Cosy experiment, limiting considerably the search for such rare decays. A new experiment, REDTOP, is being proposed, aiming at collecting more than $10^{14}$ eta/yr ($10^{12}$ eta'/yr) for studying of rare $\eta$ decays.
Such statistics are sufficient for investigating several symmetry violations, and for searches of new particles beyond the Standard Model.
Recent physics and detector studies indicate that REDTOP has excellent sensitivity to probe all four portals connecting the dark sector with the Standard Model. Furthermore, conservation laws and violation of discrete symmetries can be probed in several ways.
Several production mechanisms are available for a super $\eta$/$\eta'$-factory. They require different beam species and properties, available at different HEP or nuclear laboratories around the World.
The beam options, the corresponding physics program, and the detector for REDTOP will be discussed during the presentation.
Over the past years, a harmonic resonator type RF kicker has been developed and fabricated at JLab. Combining multiple harmonic modes, this kicker can have a synthesized waveform with fast rise/fall time (~1ns) and a high repetition rate up to 86.6 MHz. We successfully tested this kicker with beam in JLab’s Upgraded Injector Test Facility (UITF), demonstrated the principle of such a kicker. Originally designed for the EIC electron cooler’s injection/extraction, such a novel kicker concept can have a wide range of applications with beam. The EIC project proposed another set of harmonic kickers for the injection of its Rapid Cycling Synchrotron (RCS). In this paper, we will present the detail results of this test and discuss the possible applications.
The Electron-Ion Collider will utilize polarized hadron beams (protons, He3). Estimating polarization lifetime for hadrons is challenging due to the long compute times necessary and inevitable numerical noise issues. A reduced code using an evaluation of spin resonances and longitudinal effects has been developed which was benchmarked against RHIC polarization lifetime results. However this approach has known discrepancies for lifetime estimates in excess of 1 hour and possibly for spin resonances stronger than those for protons at the current working point in RHIC. Estimates for the He3 lifetime show polarization lifetime loss near 5%/hr and do not improve much using up to six snakes. Thus we need to verify these results. To this end we have benchmarked the code against direct tracking using Zgoubi at working points near stronger spin resonances for periods of time which are computationally tractable
The “Preliminary Conceptual Design Report” (preCDR) of the BESSY III facility (https://doi.org/10.5442/r0004) has been finalized at the end of August 2022 and reviewed by a Project Advisory Committee beginning of September 2022. In this paper, we give a status report of the BESSY III facility project and will discuss aspects of lattice design, technical specifications, initial developments and a first estimate of power consumption compared to BESSY II.
NICA is mainly designed for experiments with heavy ions and polarized proton and deuteron beams at an energy of the former about 13 GeV. For these purposes, appropriate SPD and MPD detectors, as well as other necessary implements, are installed in the straight sections. EDM experiment supposes use deuterons at an energy of about 240 MeV. To ensure the «Quasi-Frozen Spin» mode, E+B elements (namely, Wien Filters) are required as well. Such elements can be placed in straight sections to compensate the arc spin rotations. For EDM measurement experiments, it is necessary to operate NICA in the storage ring, and not the collider mode. To do this, it is proposed to install ByPass channels. Thus, it is possible to create a completely new regular structure in a straight section. Creating ByPass channels will make possible to engage NICA in various experiments at once.
The Electron-Ion Collider (EIC) uses the local crab crossing scheme to compensate the geometric luminosity loss. Due to space limitations, the optics at the crab cavities in the Hadron Storage Ring (HSR) is not perfectly matched to fully rule out the crab dispersion. This paper discusses the possibility of closing the crab dispersion by a dispersive RF cavity. The formula is derived and the required momentum dispersion at the RF cavity is calculated. The weak-strong simulation is performed to demonstrate this idea. The beam optics at the RF cavity is matched.
The High Luminosity upgrade of the CERN Large Hadron Collider (HL-LHC) aims to achieve stored beam energies of 680 MJ. One possible limit to the achievable intensity is the quench limit of the superconducting magnets downstream of the betatron collimation insertion. At HL-LHC beam intensities, even a tiny amount of particles leaking out of the collimation system may be sufficient to quench them. The quench limit of these magnets, when exposed to proton loss, depends crucially on a variety of parameters. It can only be accurately estimated through dedicated beam tests that determine it under realistic operating conditions. In this paper, we present the design and execution of a quench experiment carried out at the LHC in 2022 with proton beams at 6.8 TeV. We describe the experimental approach, the result, and the analysis of the test that aims to probe the collimation cleaning performance while deliberately inducing beam losses of up to 1000 kW. The result of these tests is crucial input for the need of future collimation upgrades.
For the Future Circular Collider (FCC) Conceptual Design Report (CDR), the FCC-hh collimation system was studied and optimized for proton and heavy-ion operation with up to 8.3 GJ stored beam energy. There are currently studies ongoing for an updated design baseline, including a new ring layout, compatible with the FCC-ee, and optics, with the collimation insertions being one of the areas with major changes. The adapted collimation system layout and settings for the new baseline are presented. The beam loss cleaning performance for proton beams is studied in multi-turn tracking simulations.
The Electron-Ion Collider (EIC) combines a large electron beam-beam parameter of ∼ $0.1$ and a large proton beam-beam parameter of ∼ $0.01$ to achieve a high luminosity of $10^{34}\mathrm{cm}^{−2}\mathrm{s}^{−1}$. The beam-beam interaction should not cause significant proton emittance growth during the whole storage time of 8 hours. The strong-strong simulation is self-consistent but prone to a large numerical noise. This paper presents the weak-strong simulation results with the strong electron beam modulated by the information imported by strong-strong simulation. The electron dipole coherent mode, quadrupole coherent mode, and particle-in-cell (PIC) noise are checked by this method. The result shows that the proton emittance growth caused by the electron dipole and quadrupole coherent modes is negligible. The large emittance growth observed in the strong-strong simulation is mainly caused by the PIC noise. This paper helps us understand the discrepancy between the weak-strong and strong-strong simulations.
Storage ring commissioning-like simulations are necessary to assess the feasibility of proposed future lattice designs. This paper proposes a python package for commissioning-like simulations based on python accelerator toolbox (pyAT). The software includes: 1) errors definition, 2) correction routines from open trajectory to optics and coupling correction and 3) the evaluation of the relevant parameters, such as dynamic aperture, injection efficiency and Touschek lifetime. The software is fully exploiting parallel resources (local or on a computing cluster) and is thought to be easily configured for any machine (examples are given for EBS DBA and HMBA, for PETRA IV and for FCC-ee). Whenever possible analytic formulas are made available to the user. Several examples are detailed in this paper and included in the code as demonstrations of use.
Modern synchrotron light sources are competing intensively to increase X-ray brightness and, eventually, approach the diffraction limit, which sets the final goal of lattice emittance. Recently, we propose a new optics solution aimed at reaching low emittance, using a lattice element “Complex Bend”. The Complex Bend is a sequence of dipole poles interleaved with strong alternate focusing so as to maintain the beta-function and dispersion oscillating at low values. By integrating this element in NSLS-IIU upgrade, the designed lattice emittance is around 30 pm-rad. To prove the feasibility of this new design, we have planned the key element prototype test, in the beam line with 200 MeV beam energy. We designed and fabricated the prototype complex bend, with gradient at 140 T/m. It is installed and commissioned at NSLS-II linac beamline. In this paper, we’ll report the test beamline design and beam commissioning progress
The SHADOWS experiment is a proposed beam dump experiment in the CERN North Area, aiming to search for feebly interacting particles (FIPs) created in 400 GeV/c proton interactions. Due to its intended off-axis location alongside the K12 beam line, the SHADOWS detector can be placed potentially very close to the dump, enabling it to look for FIPs in non-covered parts of the parameter space. To guarantee a good quality of a potential signal, it is crucial to reduce any backgrounds of Standard Model particles as much as possible. The dominant background downstream the beam dump is caused by muons. This gives rise to introducing a dedicated muon sweeping system consisting of magnetised iron blocks (MIBs) to actively mitigate this background component. We present the conceptional design studies in the framework of the Conventional Beams Working Group of the Physics Beyond Colliders Initiative at CERN.
Commissioning a test beamline in KEK Photon Factory Advanced Ring (PF-AR, 6.5GeV and 5.0GeV) is proceeded under cooperation with the KEK Institute for Particle and Nuclear Studies (IPNS) to use electron beams in the GeV-range for the development of detectors in particle physics experiments. The inauguration of the project which was mainly directed by the IPNS was launched back in 2014, but the project progressed after the budgeting in FY2020, and the construction was completed in the summer of 2021. The electron for beam test can be obtained from gamma-rays emitted by collisions between the halo of a stored beam, which is the synchrotron radiation source in PF-AR, and a wire target using a copper converter to electron-positron pair creation. A yielded monochromatic electron beam is guided to the test area by quadrupole magnets and a bending magnet on the test beamline; the first interaction test between the wire target and the stored beam was successfully performed in the fall of 2021 and the trial of long user operation with top-up injection was completed in the fall of 2022. In this presentation, we will report on the overview of the construction and the beam commissioning of the test beam line.
Coordinate conversion is used in many aspects, such as laser tracker transfer problem, the conversion between WGS84 coordinate system and local coordinate system and so on. The high precision of coordinate conversion model is beneficial to improve the accuracy index of the network. The dual quaternion can integrate rotation and translation, which effectively simplifies the complexity of the trig function calculation of rotation matrix, and the overall least square adjustment considers the error problem of common points, and improves the accuracy of the model from two aspects.
Within the Standard Model the electric dipole moment (EDM) of the muon is heavily suppressed. Observation of a non-zero EDM value would be an additional source of CP violation that would aid in answering the many open questions about the universe and the Standard Model. As part of an investigation into the feasibility of measuring the muon EDM at the g-2 storage ring at Fermilab, a study on the delivery of low momentum muons to the g-2 ring using the existing accelerator infrastructure is presented.
The main SPS users are the experiments installed in North
experimental Area (NA) which are served with a continuous 4.8 s long
spill of protons and heavy ions. A third-integer resonant slow extraction is used to provide a uniform, long spill. Such a technique
comes at the cost of particles directly hitting the electrostatic septum
wires and activating the surrounding of the extraction
channel. In recent years, silicon bent crystals have been exploited to shadow
the wires of the septum blade and reduce the beam induced activation.
It was then demonstrated the experimental success of local shadowing in
the SPS and a way to further reduce losses with a non-local
installation of the crystal. After the last yearly stop, a new Si bent
crystal was installed in LSS4 of the SPS. In this paper, the first
results from measurements with beam are reported together with
limitations and possible upgrades of the present installation.
In the J-PARC Muon g-2/EDM experiment, to measure muon g-2 and EDM, it is necessary to accumulate 300 MeV/c muon beams with a 66 cm diameter region with a 3 T solenoid-type magnetic field. A new three-dimensional spiral injection scheme has been invented to achieve this target. Since this is the first instance to employ this injection scheme, a scale-down experiment with an electron beam of 297 keV/c and storage beam diameter of 24 cm is established at KEK. A simplified storage beam monitor using scintillating fiber has been designed and fabricated to measure the stored beam. The 100 nanosecond width pulsed beam is injected and observed a few microsecond signals by stored beam monitor. According to this result, the beam storage is confirmed. And the recent result shows that the stored beam deviated from the design orbit and caused betatron oscillations. To measure the beam deviation quantitatively and tune the beam, the storage monitor has been updated. The data from this stored beam monitor are the primary data for considering the conceptual design of the beam monitor for the Muon g-2/EDM experiment. This talk will discuss the measurement of beam storage by three-dimensional spiral injection and beam tuning using a scintillating fiber monitor.
CNAO is one the six hadrontherapy centers all around the world that produce
both proton and carbon
ions beams.
It is based on a synchrotron in which the beams are extracted by a slow extraction mechanism that uses a betatron core.
In the last years an electrostatic exciter has been installed along the ring in order to allow
beam extraction using the RF-KO method.
The system has been commissioned and allows extraction according to the clinical beam parameters.
The paper illustrates how the RF-KO method has been implemented in CNAO under the hardware and software
point of view. The characteristics of the proton and carbon beams will be also presented.
The baseline scheme for hadron beam cooling in the Electron Ion Collider (EIC) calls for Coherent electron Cooling (CeC) of the hadrons with non-magnetized electrons at high energy (150 MeV electrons), and additional cooling via conventional bunched beam cooling using a precooler system. The electron beam parameters for these concepts are at or beyond the current state of the art, with electron bunch charges of the order of 1 nC and average currents on the order of 100 mA and require an Energy Recovery Linac (ERL) to produce such beams. Using specifications provided by BNL and Jefferson Lab, physicists and engineers at Xelera Research are working on a complete design of an ERL system capable of satisfying such a cooler.
this paper briefly introduces the layout theory and analysis basis of the first-level control network, calculates the accuracy index of the first-level control network of Hefei Advanced Light Source, designs the basic scheme of the first-level control network, and analyzes the absolute precision and relative precision of the control network in detail through the simulated adjustment data.According to the design of the basic scheme of the first level control network, the author carries on the simulation calculation of the datum, adjustment scheme, factors affecting the accuracy and measures to improve the accuracy of the control network, and determines the optimal scheme.
The Southern Advanced Photon Source (SAPS) is a 4th generation storage ring based light source under design, which is planned to be constructed at Guangdong province at China. SAPS aims at providing electron beam with emittance below 100 pm.rad and high beam current at the beam energy 3.5 GeV. At present, two injector options are still under consideration: the conventional design which include a low energy linac and a full energy booster, and the full energy linac injector. During the past two years, the nominal current of the storage ring was increased to 500 mA, so the injector system has to provide more bunch charge.In this paper, the update of the conventional linac injector is presented, which consists of a thermionic electron gun, a bunching system, a 200 MeV linac and beam transfer line from linac to booster.
As compared to traditional magnets, permanent magnets can effectively reduce energy consumption and eliminate the impact of current ripple and the wa-ter cooling system on beam current. The use of perma-nent magnets in accelerators has become a new trend as permanent magnet technology has advanced. In HALF, we have designed a permanent magnet based on the quadrupole magnet, and the central magnetic field strength of the permanent magnet can be adjusted, indicating that single or multiple permanent magnets can be developed to replace different sizes of quadru-pole magnets in accelerators, greatly improving sys-tematization. The magnet’s mechanical design has been finalized, and the prototype of the permanent magnet will be manufactured and tested soon.
The collimation systems located in the midstream of the beam line to reactor (BLR) of CiADS (China Initiative Accelerator Driven subcritical System) are designed to dissipate about 3 kW of beam power with a cleaning efficiency of higher than 99.5% of halo proton particles. To guarantee the demanded high efficiency and the design reliability, the lattice of collimation-to-target beam line are built in Monte Carlo simulation and thus the tracking of the halo particles as well as its secondary particles during-and-after collimation can be performed directly and exactly. This is essential not only for an accurate prediction of the performance of a detailed geometric design, but also for expediting the design optimization process. In addition, a distinctive three-stage collimation design combining thin scraper, jaw-shaped absorber and cylinderically-symmetric absorber is adopted for a high capture efficiency. Here the design methodology, the optimum scheme of the collimation system and its satisfactory performance are presented.
The Machine Protection System (MPS) of the Hadron Storage Ring (HSR) of the Electron-Ion Collider includes a multi-stage collimation system (MSCS) located in the IR12 straight section. However this area also includes a magnetic switchyard to allow for large circumference changes between mid-energy (41 GeV/u) and high-energy (100-275 GeV/u) operations of the HSR. The following reviews the preliminary layout of the HSR MSCS taking into account both the geometrical limitations of a crowded IR12 area as well as the lattice design constraints in terms of beam dynamics and available phase advance separation between each stage of the MSCS. The first results from long-term tracking simulations are also presented and their implications on HSR machine protection and background control are discussed.
The Advanced Wakefield Experiment (AWAKE) has demonstrated during its first run (Run1, concluded in 2018) the capability of accelerating electrons up to the energy of 2 GeV using proton driven plasma wakefield acceleration.
AWAKE Run 2 has started and during the third phase of the program, Run 2c, which aims to demonstrate stable accelerating gradients of 0.5-1 GV/m and emittance preservation of the electron bunches during acceleration, the layout of the experiment will be modified to accommodate a second plasma cell. Among the many changes, the position of the primary 18 MeV electron beam line will be shifted. The beam line layout and optics will need, therefore, to be redesigned to fit the new footprint constraints and match the new beam requirements.
This paper presents the proposed layout of the new 18 MeV line, detailing the constraints and specifications, describing the design procedure and showing the main results.
The High Energy Photon Source is a 6 GeV synchrotron radiation light source being built in Beijing, China. The electron beam inside the storage ring is designed to run with ultra-low emittance. To ensure high beam quality, the coupled bunch instabilities need to be carefully investigated and controlled, therefore an effective feedback system is essential. Stripline electrodes will be used in the HEPS storage ring as transverse feedback kickers. Besides, a tune kicker with stripline electrodes is designed to measure tune and clean undesired buckets.
The design and simulations of these kickers will be discussed, mainly including the reflection parameter, shunt impedance, and beam impedance.
A new fourth-generation synchrotron radiation source(4GSR) will be built in Ochang, South Korea by 2027. A technical design review for the Korea 4GSR is currently in progress and is expected to be completed in mid-2023.
The storage ring has a circumference of 800 m. It has been designed for a maximum current of 400 mA at 4 GeV electron beam energy. A target emittance is 58 pm-rad, 100 times less than PLS-II that is 3rd generation light source in Korea.
The RF system for the Korea 4GSR consists of 10 or more normal conducting cavities, a low-level RF(LLRF) system, a high-power RF(HPRF) system and so on. In order for the beam stability highly-HOM damped cavities will be indispensible. Subsidary the feedback system such as a longitudinal feedback system(LFS) and transverse feedback system(TFS) will be installed in the storage ring. Additionally we are planning to install harmonic cavities for Landau damping, on the other hand for improving of beam life time and less wake field. In case of the LLRF, we would try to apply new digital feedback control scheme. And the HPRF is taking account of solid state RF power amplifier.
This presentation shows the current status and plans of the RF system for the Korea 4GSR.
The Electron-Ion Collider is gearing up for "Critical Decision 2", the
project baseline with defined scope, cost and schedule.
Lattice designs are being
finalized, and preliminary component design is being carried out. Beam dynamics
studies such as dynamic aperture optimization, instability and polarization
studies, and beam-beam simulations are continuing in parallel. We report on
the latest developments and the overall status of the project, and present
the plans for future activities.
The Super Proton Synchrotron (SPS) injection system plays a fundamental role to preserve the quality of injected high-brightness beams for the Large Hadron Collider (LHC) physics program and to maintain the maximum storable intensity. The present system is the result of years of upgrades and patches of a system not conceived for such intensities and beam qualities. In this study, we propose the design of a completely new injection system for the SPS using multi-level numerical optimisation, including realistic hardware assumptions. We also present how this hierarchical optimisation framework can be adapted to other situations for optimal accelerator system design.
The Electron-Ion Collider being built at BNL features an Electron Storage Ring (ESR) and a Hadron Storage Ring (HSR) with counter-rotating beams that collide in two Interaction Regions (IRs). Synchronicity must be insured at the collision points over the entire range of ESR (5-18 GeV) and HSR (41-275 GeV/u) energies. While it is necessary to use a shorter arc for 41 GeV/u operations, the correct timing at higher HSR energies is achieved by changing the radial position of the hadron beam in the arcs.
The following reviews the HSR circumference changes needed to establish synchronicity with the ESR, as well as the implications on lattice design and modeling. The methodology for implementation of the corresponding HSR Radial Shift (RS) is presented along with the new closed orbits at high energy. The technical constraints from the RS on the power supplies of orbit correctors and IR magnets is also discussed.
The Electron-Ion Collider (EIC) at Brookhaven National Laboratory will feature an electron storage ring that will operate at a wide range of energies up to 18 GeV. Recently a study has been undertaken to extend the minimum energy from 6 GeV to 5 GeV. As the solenoid-based spin rotators require specific bending angles that depend on the energy range, this change results in major changes to the geometry. Moreover, avoiding interference of the electron beamline with the other beamlines in the tunnel, as well as with the tunnel wall, is a formidable challenge, especially at the location of the large-diameter superconducting solenoids. In this contribution, the details of the modified spin rotators and geometry matching are presented.
MYRRHA will be a research infrastructure focussed on the construction of a first prototype of a sub-critical nuclear reactor driven by a 600 MeV particle accelerator (ADS). The first phase of MYRRHA is called MINERVA and aims for the construction of a 100 MeV, 4 mA proton linear accelerator with a focus on reliability. Attached to this 100 MeV linear accelerator are a Proton Target Facility (PTF), which is essentially a high power Isotope Separation On-Line (ISOL) Facility, and a Full Power Facility (FPF) for fusion material research. The conception of the high energy beam transport lines (HEBT) at 100 MeV towards these facilities has been intensively studied over the past years. This paper presents the status of the detailed beam optic studies of the Protons Target line towards the PTF, the Full Power line towards the FPF and the beam line towards an energy tuning beam bump
Manipulating high energy beams with bent crystals has applications ranging from beam collimation to slow or direct beam extraction. These systems are now integrated parts of accelerators and studied for future experimental set-ups.
With growing achievements and expectations of crystal beam manipulation, requirements for the devices that operate the crystals become more stringent. They must retain the extreme angular precision required by the tight acceptance of crystal channeling. But they also must sustain longer operation, with higher beam energy, and provide additional functions.
In this paper are presented crystal channeling devices in operation or development at CERN. Target Extraction Crystal devices, operated in SPS ring, reduce beam power losses during slow extraction. Target Crystal Primary Collimators are now part of LHC collimation system for ions runs. Finally, two devices are currently developed for dipole moments measurement of short-lived baryons in the LHC.
This paper focuses on the relations between requirements, environment, and design of the different devices. It emphasizes how the specificity of items that share the same principle leads to unique design solutions.
Beam-based alignment (BBA) is a standard tool at accelerators for aligning particle beams to the centre of quadrupole magnets. Traditional BBA measurements have been slow, potentially taking many hours for a whole machine. We have developed a tool, based on results previously reported at the ALBA synchrotron, that uses fast excitation of magnets to greatly speed up measurements. We show results of different measurement and analysis techniques, and comparison with the currently used slow method.
Southern Advanced Photon Source (SAPS) is a 3.5GeV fourth-generation storage ring light source, considered to construction in Guangdong province of china, adjacent to the China Spallation Neutron Source(CSNS). Its natural emittance of the beam is close to the diffraction limit. Since the dynamic aperture of SAPS is far smaller than the physical aperture in the low emittance storage ring, on-axis swap-out injection scheme was adapted. Several couple sets of superfast kickers and nanosecond pulsers are needed. Due to the RF-frequency in the ring is 166.7 MHz, the gap of adjacent bunches is 6ns. In order to realize bunch-by-bunch control, the pulsers’ duration needs to be shorter than twice the minimum bunch spacing, which is a big challenge for SAPS. A prototype of fast nanosecond pulser based on semiconductor opening switch (SOS) was developed. A two-stage magnetic pulse compression system was used to pumping the SOS, which can provide with forward and reverse current of several hundreds of amperes. In this condition, the cutoff time of SOS can be reach several nanoseconds, which could meet the requirements of SAPS. The performance of the prototype can produce a pulse at 50Ω, with FWHM （50%-50%）of 5.6ns，bottom width(10%-10%) <12ns，an amplitude of 18kV. In this paper, the design, simulation and test results are presented.
The Electron-Ion Collider (EIC) presently under construction at Brookhaven National Laboratory will collide polarized high energy electron beams with hadron beams with luminosities up to 10^34cm^{-2}s^{-1} in the center mass energy range of 20-140 GeV. Besides high luminosity and high polarization, it is also recommended for the EIC design to incorporate a possible second interaction region (IR). In this article, we evaluate the dynamic aperture of the Hadron Storage Ring (HSR) design lattice with two IRs. The large nonlinear chromaticities from the two IRs will be compensated with multiple arc sextupole families. The tolerances of IR magnetic field errors are to be determined.
The Electron-Ion Collider (EIC) will be constructed at Brookhaven National Laboratory with the goal of providing high luminosity and high beam polarization for a large range of colliding beam energies. One critical design requirement is a large dynamic aperture (DA) of the colliding rings, in both transverse and momentum dimensions. To satisfy numerous geometric and optics conditions, the ring lattices have been continuously the subject to adjustment and improvement. This paper presents results of the DA optimization studies for the latest lattice designs of the Electron Storage Ring at different energies, including description of the non-linear chromaticity compensation, the impact of magnet errors, and the field tolerances.
We frequently experience earthquakes in Japan. Even though countermeasures against earthquake is deeply considered and well carried out, sometime troubles are occurred on facilities or experimental devices. When we focus on the relative displacement due to an earthquake, it is possible to cause damage of a beam pipe bellows or interference by disappearing tolerance between the sub-detectors. And magnet quenches have been triggered due to relative displacement of magnetic fields between three superconducting solenoids, i.e., the detector solenoid and two compensating solenoids in each final focus magnets, when earthquake occurred. So, we set acceleration sensors, the relative displacements had been measured. And also, laser distance sensors and gap sensors mounting on the final focus magnets were referred for this study. From these measurement data, characteristics of earthquakes were analyzed. Measurement acceleration data was also applied for response spectrum analysis. In this presentation, we will present the measurements and analysis results, and comparison between the measurements and the FEM calculations are shown.
Proton bunches will collide with electron bunches in the Electron-Ion Collider (EIC) to produce a luminosity of up to $10^{34} \mathrm{cm}^{−2}\mathrm{s}^{−1}$. Many sources can lead to the electron orbit ripple at the interaction point (IP). This ripple will cause the emittance growth of the proton beam via beam-beam interaction. This paper presents the weak-strong simulation in which the strong electron beam is distorted by the orbit ripple. The frequency of the ripple is scanned to obtain the maximum tolerable amplitude. At the low frequency, different proton parameters are tested to reduce the emittance growth. The driving strength of the proton beam emittance growth is discussed. The simulation results are benchmarked with the analytic formula. This paper will provide a reference to the engineering design for the Electron Storage Ring (ESR) in EIC.
Polarization levels in the Electron Storage Ring (ESR) of the Electron-Ion Collider (EIC) must be maintained for a sufficient time before depolarized bunches are replaced. The depolarizing effects of synchrotron radiation can be minimized with spin matching, however the optics requirements for the ring must still be satisfied. Furthermore, the robustness of the polarization in the presence of misalignments, beam-beam effects, and the eventual insertion of a vertical emittance creator – necessary to match the electron and ion beam sizes at the interaction point – must be ensured. In this work, the results of various nonlinear Monte Carlo spin tracking studies of the ESR lattices are presented, and their implications discussed; the necessity for a longitudinal spin match in the 18 GeV case is investigated, and vertical emittance creation schemes with minimal effects on polarization are analyzed.
The EIC electron beam parameters will feature 320 kJ stored kinetic energy and beam sizes leading to the melting of most metals in case of normal impact of a single bunch. In order to protect the aperture, focusing magnets and experimental detectors from beam losses and backgrounds a dedicated collimation system will be included in IR2 and IR4. Additionally, to protect against accidental losses from failures and continuous losses from swapping bunches, kickers and absorbers will be added to IR12 and IR2. This paper describes the current design for these two systems including material choices and specifications.
Dust particles interacting with the proton beams have caused many thousand beam-loss events at CERN's Large Hadron Collider (LHC), some of which led to premature beam dumps and even magnet quenches. It has been hypothesized that dust particles on the vacuum chamber wall of the LHC are negatively charged due to electron clouds and can detach from the chamber wall by the electric field of the beam. To test this hypothesis, we performed experiments to study the electrostatic lofting of dust particles from a conducting surface. A monolayer of SiO2 particles with a diameter of <44 um is deposited on such a surface and exposed to an electron beam of 80-140 eV. An external electric field of up to 3 kV/cm is then applied. The properties of dust charging and levitation are characterized from recorded high-speed videos. We observed that dust particles are lofted both during electron beam charging and during the application of the external electric field. Our results provide experimental evidence that dust particles can be detached from a conducting surface and help to understand the mechanism of how dust particles can enter the LHC beam.
Elettra 2.0 is the name of the upgrade project of the existing Elettra Storage Ring (SR) and its ancillary systems. The project comprises also new beamlines (BLs) and the re-allocation of some of the currently operational ones.
Consequently, the “Experimental Hall” (EH) of Elettra, i.e. where the beamlines are installed, is another working area with activities that have started well before the scheduled “Dark Time” (DT) when we will dismantle Elettra and install Elettra 2.0.
The installation of the beamlines implies, among many more activities, the partial reconfiguration of the shielding wall of the SR tunnel. Some of these local re-arrangements can be performed before the DT, during maintenance shutdowns of Elettra, in those portion of the EH not currently occupied by working beamlines.
The reconfiguration of the shielding wall requires a design that merges SR and BLs specifications, as well as careful planning of on-site activities, spanning from survey and tracing of the new positions of the blocks, to plants re-arrangement, to handling and transportation of concrete blocks up to 6 tons.
This paper illustrates the status of the reconfiguration activities of the Experimental Hall.
The LHC beam dump system has the task of safely and reliably disposing of the extracted beams from 450 GeV to 7 TeV. The present dump assembly consists of a multi-segment graphite core, which is contained in a duplex stainless steel vessel with titanium windows. To reduce the energy deposition density in the core and windows, the extracted beams are swept across the dump front face with dedicated dilution kickers. In the High Luminosity-LHC (HL-LHC) era, the dump must withstand beams with a significantly higher stored energy (about 700 MJ) than has been achieved so far (380 MJ). The high temperatures and vibrations generated in the core and vessel require a redesign of the dump assembly to ensure safe operation with HL-LHC beams. This work presents energy deposition studies for the different dump components in case of regular dumps and possible dilution kicker failure scenarios during HL-LHC operation. The impact of different design choices, such as the dump core segmentation, on the energy deposition and the leakage of particles from the dump is discussed.
Steering of high-energy particle beam can be achieved by exploiting channeling in bent crystals. Indeed, the atomic planes of a crystal lattice aligned with incoming particles acts similarly to a waveguide and deliver deflection equivalent to hundreds of Tesla magnetic dipole. This effect was investigated and exploited in accelerators since the 70s and is being currently tested at CERN as a baseline element for HL-LHC. Indeed, channeling is particularly efficient for positive particles, achieving deflection for up to ~80% of channeled particles. Nevertheless, the remaining 20% losses are a primary constrain for bent crystal installation and use in accelerators. The GALORE project is currently aiming to overcome this key limitation by developing a new type of bent crystals which could potentially completely suppress such losses. This goal can be achieved by machining of a microscopic structure on the crystal in order to affect channeled particles dynamics. The success of the project would not only improve current setups but also enable completely new schemes for crystal-assisted beam manipulation. We report the latest result of the project and of the crystal prototypes produced.
We discuss the beam power loss related to the heating of the beam pipe walls of the FCC-ee interaction region. We analyse the excitation of trapped modes, which can accumulate electromagnetic energy and determine the locations of these modes. We study the unavoidable resistive-wall wake field, which is responsible for the direct beam pipe walls heating. We show the distribution of the heat load along the central part of the interaction region. We also present the cooling system design and results for temperature distribution in interaction region in the operational mode.
The BEPCII has already realized the collision luminosity target of $1.0\times10^{33}cm^{-2}s^{-1}$ in April 2016. However, in the past six years of practical operation, the collision luminosity usually remains between $6.0\times10^{32}cm^{-2}s^{-1}$ and $8.5\times10^{32}cm^{-2}s^{-1}$. In the operation with high beam current, the BEPCⅡ displayed serious beam instabilities, which greatly limits the increase of collision luminosity. A series of machine studies and analyses were conducted. According to the bunch lengthening experiments, the longitudinal effective impedance is $0.162\Omega$ for electron storage ring and $0.195\Omega$ for positron storage ring. According to the tune shift measurements, the transverse effective impedances are $0.02840\Omega/m$ horizontally and $0.05253\Omega/m$ vertically for electron storage ring, and $0.04223\Omega/m$ horizontally and $0.06714\Omega/m$ vertically for positron storage ring. The oscillation mode distribution was obtained from experiments, showing that the transverse beam coupling instability has become an important factor for limiting the increase of beam current and luminosity. Finally, some possible origins of transverse narrow-band impedance, such as the resistive wall and vertical masks, were checked. The calculated results match with the experiment results quite well. The results in this study give important references for establishing feedback systems and increasing the collision luminosity in the future research.
Steady-state microbunching (SSMB) is envisioned to enable the generation of high-power coherent synchrotron radiation at an electron storage ring for wavelengths up to the extreme ultraviolet. The underlying mechanism has been shown to be viable in a proof-of-principle (PoP) experiment at the Metrology Light Source (MLS) in Berlin*.
An enhanced detection scheme allows systematic studies of the conditions needed for the creation of microbunches within the continuing PoP experiment**. It was found that the generation of coherent radiation from microbunches is favored in specific nonlinear longitudinal phase space structures, known as “alpha buckets”, which arise when the momentum compaction function becomes dominated by higher order terms.
We present the most recent experimental results and their interpretation as well as accompanying simulation results.
A new collaboration between ESRF and DESY within the EURIZON project is aiming at building tools and concepts that can be used for the next generation light sources. The developed tools will be applied to the ESRF-EBS and the PETRA IV lattice models to validate concepts to improve the injection efficiency or the lifetime of storage rings.
In this project framework, the bounded Extremum Seeking (ES) algorithm is being studied as a Touschek lifetime optimization procedure. This contribution presents the tests performed on the ESRF-EBS electron beam where several sextupole and skew quadrupole knobs were tuned at the same time for vertical emittance minimization first and subsequently lifetime maximizsation.
The Future Circular Collider project is built around two main pillars: the construction of 100 km lepton collider running at increasing energies from the Z-pole to the t-tbar threshold (FCC_ee) followed by a hadron collider in the same tunnel (FCC_hh) to explore unprecedented energy frontier.
The realization of FCC_ee relies on a very challenging injector complex that should provide the highest ever realized source of positrons, which will serve the first phase of the collider operations (Z-pole). In this contribution the relevant aspects related to the damping of the high-emittance beam coming from the positron source and the transport of the damped beam within the different LINAC of the injector complex are presented and discussed.
To improve the performance of beam orbit correction, it is necessary to perform beam-based alignment in modern storage ring light sources. For the High Energy Photon Source (HEPS), a 4th generation storage ring light source being built in China, because of the large number of BPMs in storage ring, it may take dozens of hours to complete the alignment with a conventional BBA algorithm. To reduce the time cost, it has been proposed to use ac excitation for fast beam-based alignment. We tested the feasibility of applying this method to the HEPS storage ring through numerical simulations. In the following, we will introduce the simulation settings and the corresponding results.
The Fermilab Muon Campus, repurposed Tevatron-era Antiproton Source facilities, is currently the home to the g-2 and Mu2e muon experiments. Collecting data since 2017, the g-2 experiment is currently running and will switch to a mu-minus mode before the Muon Campus transitions to Mu2e operation. Currently in the commissioning process, the Mu2e experiment is expected to begin calibration and data collection in fiscal year 2024. A majority of the Muon Campus is shared between the two experiments, however the modes of operation for each are significantly different. An 8 GeV primary proton beam strikes a target to produce a 3.1 GeV/c secondary muon beam for g-2, while the Mu2e experiment uses the Delivery Ring, formerly the Antiproton Accumulator Ring, for a pulsed, resonantly extracted, 8 kW, 8 GeV proton beam incident on a target in the experiment's target hall to produce a muon beam for the experiment. The current state of the Muon Campus, the current and future plans of the g-2 and Mu2e experiments, including the transition between operating modes, and the challenges associated with Mu2e operation will be presented.
The SuperKEKB accelerator, a 7 GeV electron and a 4 GeV positron double-ring collider, is in progress in order to explore the new physics beyond the standard model.
The next milestone is to obtain integrated luminosity of 15 /ab data in the next decade,
so that the luminosity should exceed 2 x 10^35 /cm^2/s in several years.
One of the essential issues is the injection performances for both rings to be capable of storing beams of a few amperes due to overcoming their short lifetimes.
The key component of the injection system is the septum magnets.
It has been found that a transverse fringe field near the septum plate has sizable multipole components.
A tracking simulation shows such fringe fields induce a vertical non-Gaussian tail,
which could cause a beam background as well as a bad injection efficiency.
Adjustment of Q-magnets for cancellation does not work perfectly for non-linear components.
To reduce the multipole region contributes to the injection amplitude to be smaller, and so, that derives improvements of injection performances.
This paper reports about the field quality improvement of the septum magnet for the SuperKEKB HER injection system.
The bunches passing through the cavity inherently have some offsets that can excite Higher Oder Modes (HOMs). In the energy recovery linacs, the transverse regenerative beam breakup (BBU) instabilities dominate and set the beam threshold current for stable beam operation. In this work, we show the choice of filling pattern and recirculation scheme for a multi-pass energy recovery linac can drastically impact the BBU instabilities by simulation.
The PERLE (Powerful Energy Recovery Linac for Experiments) project relies on superconducting RF (SRF) cavities to reach its goals. The installation of coaxial couplers on the cutoff tubes of SRF cavities is foreseen for damping cavity’s Higher Order Modes (HOMs). The prototyping and fabrication of 3D-printed HOM couplers for the PERLE cavity have recently started in collaboration with JLab and CERN. This paper provides an overview of the design of the fabricated HOM couplers and the first measurements of the cavity’s HOMs at warm on an 801.58 MHz single-cell copper cavity to validate coupler design performances. Measured cavity data is also compared to eigenmode and multi-beam wakefield simulations to confirm simulated results and see to what extent any reduction in damping can be predicted.
Diamond-II lattice is based on the ESRF-EBS cell with the central dipole replaced by a (chromatic) mid-straight, and a -I transformer, with a higher order achromat and dispersion bumps used to control the nonlinear dynamics. The majority of insertion devices currently in operation in Diamond will be either retained or upgraded as part of the Diamond-II programme, and the new mid-straights allow the total number of ID beamlines to be increased from 28 to 36. In this paper we report on the latest ID parameters and compensation schemes, as well as efforts to improve the machine optics with the aim of maximising lifetime and dynamic aperture in the presence if IDs.
The Mu2e Experiment has stringent beam structure requirements; namely, its short (~200 ns) proton bunches separated by 1.5-2.0 microseconds. This beam structure will be produced using the Fermilab 8 GeV Booster, the 8 GeV Recycler Ring, and the Delivery Ring, which was formerly part of the antiproton accumulator system. The 1.7 microsecond period of the Delivery Ring will generate the required beams structure by means of a third order resonant extraction system operating on a single circulating bunch.
The electrostatic septum (ESS) for this system is particularly challenging, requiring 100 kV over 15 mm. This poster describes a graphical user interface that has been developed to automate the conditioning and commissioning process for the ESS. It is based on an interface to the Fermilab ACNET system using the ACSys Python Data Pool Manager Client produced and maintained by Fermilab Accelerator Controls.
Network interfacing between data pool managers made by the application and ACNET devices introduce an inherent (~1 s) latency in throughput of the readouts. This delay is utilized to process and graph incoming data events of devices crucial to conditioning of the ESS. 'Ramping' and 'Monitoring' modes adjust settings of the power supply based on internal logic to efficaciously increase and maintain a high voltage in the ESS; easing the voltage setting on incidence of sparking or other errors. A timestamped log file is produced as the application runs.
The longitudinal distribution of the electron beam in the electron storage ring of the Electron-Ion Collider will be modified by the machine impedance. The modified distribution, combined with crab cavities may have an impact on the quality of the hadron beam during the collision. In this paper, we will explore the possible impact on the hadron beam quality with strong-strong and weak-strong beam-beam simulations.
Energy Recovery Linac (ERL) light source facilities, based on superconducting radiofrequency (SRF) technologies, are deemed among the
most promising technique in the future of accelerator physics. We discuss high order mode (HOM) analysis in a two-pass two-way ERL scheme, where the linac runs in a continuous waves mode with a high repetition rate for a long timescale. The acceleration and deceleration of electron bunches are supported by standing wave cavities. In order to overcome the limitations imposed by high currents and insure energy recovery over millions of interactions, accurate beam dynamics studies are required. The beam dynamics analysis reported in this paper is based on an Energy Budget Model which make use of a set of differential equations where the contribution to power losses due to HOM can be included.
The PERLE (Powerful Energy Recovery Linac for Experiments) is a multi-turn energy recovery linac (ERL) currently under study and later to be hosted at IJCLab in Orsay (France). The 500 MeV configuration considers two parallel 82 MeV superconducting linac cryomodules, each containing four 801.58 MHz 5-cell elliptical Nb cavities. Due to the high operating current and multiple passes, High Order Mode (HOM) damping in the PERLE cavities becomes fundamental to avoid beam breakup (BBU) instabilities and reduce the heat load at cryogenic temperature. This paper compares different HOM damping schemes for the PERLE superconducting RF cavity to lower the parasitic longitudinal and transverse impedance. The RF and thermal behavior of the HOM couplers are discussed. The HOM damping and power for each damping option are also computed and benchmarked with measurements.
The new EBS machine was commissioned in 2020 with a targeted nominal beam emittance of 139pm.rad in the horizontal plane. The radiated energy in the 70 insertion devices present from the restart was expected to change the equilibrium emittance. This paper presents the prevision and the measurements performed as a function of the total radiated power in the machine. The comparison shows that the non zero dispersion present in the insertion devices has a visible impact on the emittance reduction.
The concept of steady-state microbunching (SSMB) as a new scheme for the production of high power synchrotron radiation has been demonstrated at the Metrology Light Source in Berlin-Adlershof (MLS) [1].
At the MLS the same undulator section is used for the generation of the micro-structures onto the electron bunch as well as for the detection of the resulting coherent radiation from the micro-bunches one turn later. Due to the enormous difference in the pulse energy of the micro-bucket generating laser and the coherent undulator pulses showing up 160 ns later, the detection is not straightforward. We show in detail the detection scheme, mostly based on fast optical shutters, and the triggering scheme of the experiment. Ideas for further improvements are discussed.
[1] X. Deng et al., Nature, Volume 590, Issue 7847
The 7-GeV low-emittance electron beam is essential to be delivered to the SuperKEKB double-ring collider. One of the issues at the complicated beam transport between the linear accelerator and the High-Energy Ring (HER) is significant transverse emittance growth. In general, both incoherent and coherent synchrotron radiation effects play crucial roles in beam behavior. In this paper, we present the measured emittance results of the nominal optics with the help of particle tracking simulations.
CNAO is one the six centers all around the world able to treat patients affected from cancer by proton and carbon
ions beams. Beams are produced by a synchrotron equipped with two sources. A third source has been recently
installed in order to produce new species that will be interesting both for clinical and R&D purposes.
A new low energy line has been designed, installed and commissioned to transport beams from the new source
to the accelerator. In this paper the new line, called LEBTO3, is presented.
We present the latest development for the FCC-ee interaction region. It represents a major challenge for the FCC-ee colliders, which has to achieve extremely high luminosity over a wide range of centre-of-mass energies. FCC-ee will host two or four high-precision experiments. The machine parameters have to be well controlled and the design of the machine-detector-interface has to be carefully optimized. In particular, the complex final focus hosted in the detector region has to be carefully designed, and the impact of beam losses and of any type of synchrotron radiation generated in the interaction region, including beamstrahlung, have to be simulated in detail. We discuss mitigation measures and the expected impact of beam losses and radiation on the detector background. We also report the progress of the mechanical model of the interaction region layout, including the engineering design of the central beampipe, and other MDI components.
The Electron-Ion Collider, to be constructed at Brookhaven National Laboratory, requires a large dynamic aperture (DA) of the electron storage ring (ESR) for stable operation of 10 beam sigma for the transverse aperture and 1% for the momentum aperture. In particular for operations at the top energy of 18 GeV this has not been easy to achieve, and the DA has proven sensitive to small changes. Nevertheless, a chromaticity-correction scheme has been developed for the bare lattice. There are several important effects in the interaction region that are potentially damaging to the ESR’s DA, including the beam-beam interaction, crab cavity kicks, the detector solenoid field, and skew quadrupoles for coupling compensation. In this contribution, these effects are modelled to evaluate their impact on the dynamic aperture of the ESR at 18GeV.
Initiated through the Physics Beyond Colliders (PBC) Study Group there is a strong interest from the scientific community to exploit the full intensity potential of the Super Proton Synchrotron (SPS) at CERN for Fixed Target physics experiments before the end of this decade. With the ECN3 cavern in the North Area (NA) identified as a suitable candidate location for a future high-intensity experimental facility compatible with a large variety of experiments, the new PBC ECN3 Beam Delivery Task Force was mandated to assess the feasibility of delivering a slow extracted beam of up to 4x10^19 protons per year at 400 GeV. This contribution summarises the conclusions of the multifaceted beam physics and engineering studies that have been carried out recently to understand the present intensity limitations and to find technical solutions to meet the request for higher intensity in the NA transfer lines towards ECN3. The necessary modifications to the beam lines, the primary target area, beam instrumentation and intercepting devices, as well as the relevant infrastructure and services are outlined, along with a timeline compatible with the NA consolidation project that is already underway.
The Southern Advanced Photon Source (SAPS) is a 3.5 GeV, kilometer-scale, ultra-low emittance storage ring to be built next to the CSNS(China Spallation Neutron Source) in Guangdong Dongguan, China. A preliminary lattice design for SAPS storage ring with an emittance of 32 pm.rad has been proposed before. Now, the SAPS lattice is continuously under extensive design and optimization. In this paper, the latest design of lattice is introduced, and the linear and nonlinear optimization is presented.
The Electron-Ion Collider (EIC) will collide electrons and hadrons together at center-of-mass energies up to 140 GeV (in the case of electron-proton collisions). The project is currently in the design phase. The 3.8-kilometer Electron Storage Ring (ESR) will store electrons with a range of energies up to 18 GeV for collisions at one or two interaction points. The ESR consists of six arcs and six straight sections. At energies up to 10 GeV, the arcs will be tuned to provide 60 degree phase advance per cell in both planes, whereas at top energy of 18 GeV a 90 degree phase advance per cell will be used, which compensates somewhat for the emittance increase with energy. In addition, the interaction regions are very complex and constrained, featuring solenoid-based spin rotators, local coupling correction using skew quadrupoles, and many magnetic elements in a short space. In this contribution some challenging studies for the optics design are presented and discussed.
The Metrology Light Source (MLS) is a 630 MeV electron storage ring as a synchrotron radiation source for the THz to extreme UV spectral range. Its upgrade project MLS II is defined as a compact 0.8 GeV storage ring with multiple operation modes, which pursues lower emittance (<50 nm) in standard mode and preserves the strong capability of the MLS to manipulate the momentum compaction and its higher-order terms for short bunch mode. This paper presents the lattice options based on double-bend achromat (DBA), triple-bend achromat (TBA) and quarduple-bend achromat (QBA).
The Helmholtz-Center of Berlin has an ambitious plan to build a fourth-order synchrotron light source, BESSY3, as being the successor of the current BESSY2 facility. The most recent developments are centered around two promising concepts: Each of them consists of a multi-bend-achromat (MBA) section with four unit cells. The MBA cells consist either of combined-function (CF) bends and separated functions (SF) in the trailing dispersion suppressing cells (DSCs) or (the alternative design concept) SF bends and either CF or SF bends in the DSCs. In this study we present a first comparison between simulated intra-beam scattering (IBS) and Touschek beam lifetime estimates for those designs.
UVSOR, a low energy synchrotron light source, has been operational for about 40 years. It has been providing high brightness VUV radiation to users but also providing a research environment for light source technology developments. In this paper, first, we briefly review the history of the light source developments at UVSOR. Then, we describe a beamline BL1U, which is currently used for developments and applications of novel light source technologies. The beamline is equipped with two variable polarized undulators with a phase-shifter magnet and with a femto-second laser system which is synchronized with the RF acceleration. We have been developing resonator free electron laser, coherent harmonic generation, coherent synchrotron radiation, inverse Compton scattering, spatiotemporal-structured light and have been exploring their applications, in collaboration with researchers from universities and research institutes. We present the present status of BL1U and some recent results.
Among the possible future lepton colliders under study, circular muon colliders have the largest potential of reaching center-of-mass energies of 10+ TeV. Being more massive than electrons and positrons, muons are much less affected by synchrotron radiation emission, but they suffer from the drawback of having a limited lifetime. As a consequence of their decay, intense secondary radiation fields are generated in the collider, which can considerably disrupt the detector performance, both as physics background and as a cause of long-term material degradation. The machine-detector interface in a muon collider therefore requires a careful design, integrating massive shielding elements between the detector and final focus magnets. In this paper, we devise an interaction region design for a 10 TeV muon collider with a final focus triplet. We quantify the flux of secondary particles entering the detector by means of shower simulations and provide a first optimization of the shielding configuration. We also present first estimates of the power deposition and radiation damage in final focus magnets.
Muon collisions are considered again a promising means for exploring the energy frontier, leading to a detailed study of the possible feasibility issues. While the final goal is to reach centre-of-mass energies of 10 TeV or more, an intermediate lower-energy 3 TeV stage is considered. In both cases, beam intensities of the order of 10^12 muons per bunch are needed to achieve the necessary luminosity, generating a high flux of secondary and tertiary particles that reach both the machine elements and the detector region.
A strategy to reduce the beam-induced background to manageable levels has been presented in the past for the 1.5 TeV centre-of-mass energy. In this contribution, the same approach is applied to the 3 TeV case for studying the effects of the beam-induced background on the detector in the previously unexplored regime. The configuration of the interaction region will be presented with a particular focus on the absorber design, as well as the overall background-mitigation strategy with the relevant detector parameters in mind.
The proposed strong hadron cooler for the Electron-Ion Collider contains regions that transport beams with different energies. In this paper we present a possible magnet design for a broad range of beam energies.
PERLE (Powerful Energy Recovery LINAC for Experiment) is a high-power Energy Recovery LINAC (ERL) facility with 20 mA beam current and beam energy from 250 MeV to 500 MeV featuring three passes through two cryomodules. It is a hub for validation of the ERL technology development towards future energy and intensity frontier machines. Design challenges of PERLE and its beam parameters make it a testbed to validate multi-turn high current ERL operation for the LHeC. It will be the first ERL for some pioneering experiment of the eN interaction with radioactive nuclei.
In this work, design and optimization of the commutational magnet (B-com) used to spread/combine the three beams and one series of the quadrupole magnet is discussed. It gives the design parameters including: yoke geometry, pole profile, and material, and calculation of the excitation current needed to drive the magnet, the coil parameters and the number of turns.
The B-com magnet is optimized for a 30° bending angle with magnetic field of 0.88 T along the magnet length and a harmonic content of 0.036%. The quadrupole magnet is designed for a gradient field of 34.15 T/m and experiences saturation above this value. Further studies to avoid saturation and achieve the maximum gradient of 44.1 T/m required by the beam dynamics is undergoing.
The diffraction-limited storage ring (DLSR) of the Southern Advanced Photon Source (SAPS) use a large number of ultra-high gradient quadrupoles and sextupoles, which leads to the tight tolerance of beam parameters to magnetic errors. We showed the results of the magnetic error effects in previous published article. On this foundation, the magnetic error corrections are finished, including the closed orbit correction, beam optics correction and vertical dispersion correction.
The International Linear Collider is a planned electron-positron linear collider with its positron source producing positrons by exposing a target to undulator radiation. The resulting, highly divergent positron beam requires optical matching to improve its luminosity and therefore the success of the collision experiments. Here, optical matching refers to capturing particles, i.e. making them available for downstream beamline elements. In the past, this has been done with sophisticated coils, but recently the usage of a current-carrying plasma, a plasma lens, has been proposed. For the International Linear Collider particle tracking simulations have already concluded with an optimal plasma lens design with respect to the captured positron yield. This design is characterized by a linearly widening radius in beam direction. Now further research and development is required, including both experiments with a prototype set-up as well as simulations modeling the hydrodynamics of a current-carrying plasma and the resulting magnetic field. The accuracy of the latter will benefit greatly from the former. First results of these magnetohydrodynamic simulations are discussed in the following.
Octupoles are often used to dampen beam instabilities caused by space charge, however the insertion of octupole magnets leads to a non-integrable lattice which reduces the area of stable particle motion. One proposed solution is Quasi-Integrable optics (QIO), where the octupoles are inserted between a specially designed lattice called a T-insert. An octupole with a strength that scales as 1/β^3 is applied in the drift region to create a time independent octupole field, leading to a lattice which is close to integrable. This means that large tune spreads can be achieved without reducing the dynamic aperture. IBEX is a Paul trap which allows the transverse dynamics of a collection of trapped particles to be studied, mimicking the propagation through multiple quadrupole lattice periods, whilst remaining stationary in the laboratory frame. We present our experimental results from testing QIO with space charge in IBEX.
Modernization of the NESTOR hard X-ray generator storage ring for switching to the operating frequency of the accelerator of 2.856 GHz requires corresponding changes in the design of the high-frequency system, and this, in turn, leads to the need to modernize the laser-optical system. The necessary calculations were carried out to determine the new characteristics of the pulsed laser, the Fabry-Perot cavity, and the lens optical system matching the beam geometry. The obtained results confirm the possibility to use an already existing laser-optical system at a new operating frequency of the accelerator with some changes in the design.
To satisfy up-to-date technical requirements NSC KIPT hard X-ray source on the base of Compton scattering NESTOR should be modified. Essential modernization should be done in accelerator-injector, lattice of the storage ring, RF and optical systems.
In the paper the technical proposals of the facility modernizations and results of beam dynamic simulations in the modified facility are presented and described.
KEK has two light sources: Photon Factory (PF, 2.5 GeV) and Photon Factory Advanced Ring (PF-AR, 6.5 GeV). In 2017, the use of a new beam transport line (BT) of PF-AR was started, and the simultaneous top-up injection for both PF and PF-AR was realized. These days, there have been strong demands for the reduction of the operating cost of accelerators, and its importance is greater in PF-AR with higher ring-energy. In 2019, the 5 GeV operation was started in PF-AR. However, the new BT of PF-AR (ARBT) was designed for the energy of 6.5 GeV, then the simultaneous top-up injection is no longer available under the condition of 5 GeV operation of PF-AR and 2.5 GeV operation of PF. In order to mitigate this impact, the pseudo-top-top injection has been employed by fine-tuning the current of a common DC bending magnet placed at the intersection of ARBT and the BT of PF (PFBT) within a given time frame. However, this scheme limits the operation schedules, and will not be able to respond adequately to low emittance optics of PF-AR that may bring the shorter beam lifetime. In order to realize true-top-up injection, a modification of BTs’ optics design was carried out. This time, details of modified design of BTs’ optics and its extended plan will be presented.
The system in place for remote alignment of the girders, which carry the storage ring elements of the PETRA III light source in the Max von Laue experimental hall, were never used to perform re-alignments after the initial installation of the storage ring in 2009. Since the planned upgrade, PETRA IV, can benefit from the fine control of the girder position to achieve the design beam performance, a movement test of one of the PETRA III girders was performed in December 2022. The ability to safely and precisely remote control the equipment was demonstrated and the accuracy of the optics model that describes the effect of the girder movement on the orbit could be evaluated. The findings of this experiment are summarized in this paper.
Transverse multibunch instabilities are of significant interest in accelerators with strong wakes and large bunch trains. In such cases, wakes that do not damp sufficiently from bunch to bunch can drive instability along the entire bunch train. Simulations are useful for understanding such instabilities, but the multiscale nature of the system and numerical noise can make results uncertain. A linearized multibunch model will be applied to study multibunch instabilities, and potential applications for the future electron ion collider project will be explored.
The Electron Ion Collider Hadron Storage Ring lattice includes Siberian snakes to preserve beam polarization during the acceleration ramp to store energy, where 70% polarization has to be achieved. With comparable depolarizing resonance strengths in HSR and in today's RHIC lattice, proton beams should be satisfied with RHIC pair of pi-apart snakes, which will be maintained in the HSR. On the other hand, with about twice as strong depolarizing resonance strengths, more snakes are needed for helion beams. Four- and six-snake schemes have been studied in the HSR lattice and optics configuration, and optimized to satisfy the EIC polarization requirements. Methods and design outcomes are reported.
A method to reconstruct the momentum distribution of the injected muon beam in the Muon g-2 Storage Ring at Fermilab has been developed, which is based on beam profile measurements from the Muon g-2 straw tracking detectors as input. Extending a spectrometric perspective to the muons injected into the Muon g-2 storage ring, a direct transformation of the beam radial coordinates when the distribution recreates the initial beam conditions and when the muons are separated proportionally to their magnetic rigidities provides a precise method to measure the energy distribution of the stored beam. The obtained energy distribution can be used to quantify the dominant beam-dynamics corrections to the final measurement of the muon g-2 experiment.
With High Luminosity Large Hadron Collider (HL-LHC) beam intensities, there are concerns that beam losses in the dispersion suppressors around the betatron cleaning insertion could exceed the quench limits. The planned upgrade to install a new collimator between two new 11 T dipoles has been deferred due to the ongoing development of the new magnets. As a result, other beam loss mitigations are studied for the HL-LHC startup in 2029. Collimation impedance is another concern for HL-LHC, as betatron collimators have small operational gaps. A new optics was developed which increases the beta function in the collimation area, as well as the single pass dispersion from the primary collimators to the downstream shower absorbers. This optics was tested with 6.8 TeV beams at the LHC in a dedicated machine experiment in 2022. This paper reviews the performance of the new optics and discusses the prospects for future operational deployment.
The 18 GeV Electron Storage Ring (ESR) lattice of the Electron-Ion Collider (EIC) showed various undesirable effects in nonlinear Monte Carlo tracking, including a vertical core emittance exceeding radiation-integral predictions and a low asymptotic polarization. These problems were resolved in a newer lattice where dispersion in the solenoidal spin rotators is set to zero. Here we identify the cause of the effects as a 2nd order synchro-beta resonance which is driven by vertical dispersion in the quadrupoles of the rotators. The 5 and 10 GeV ESR lattices have small but nonzero dispersion in the rotators, and misalignments in the 18 GeV case will inevitably create some dispersion, so care must be taken that this 2nd order resonance is not excited. Zero dispersion in the spin rotators may therefore not be the best solution, and a new working point is sought that is not close to this resonance. The implications of this result on the design of the ESR – including achieving a longitudinal spin match – are explored.
Fractional harmonic cavities could increase the versatility of 4th generation storage ring based light sources providing a capability to deliver short and long bunches simultaneously. To maintain some reasonable short bunch length capabilities combined with a practical beam lifetime in low emittance storage rings, a combination of half-integer with integer harmonic RF system can be of interest. In this paper we explore the use of a normal conducting, active, HOM-damped 3.5th harmonic cavity system at 1.75GHz in BESSY II light source and explore it application in future BESSY III facility. An overview on the status of the project with respect to RF design, integration & system will be given. Some results of beam dynamics simulations for BESSY II and BESSY III will be presented.
The booster ring of High Energy Photon Source, with a circumference of 454 m, is responsible for ramping the beam energy from 500 MeV to 6 GeV at a repetition rate of 1 Hz. Six Petra type 5-cell copper cavities were chosen to provide a total accelerating voltage of 8 MV and a total beam power of 52 kW. To fulfill the specific requirements of the HEPS booster, several modifications were made on the original design from Research Instruments (RI). Six cavities manufactured by RI have been delivered to HEPS and high-power tested successively from April to December 2022.
Cavities were tested up to a maximum rf power of CW 120 kW, which is the reliable capability of the power coupler specified by RI. Power-keeping at the maximum rf power was conducted subsequently, with an average time of 100 hours. Finally, in order to verify the performance during real operation, the ramped run was conducted according to the pre-defined curve required by the physics design at a repetition rate of 1 Hz, with all control loops closed (cavity frequency loop, cavity field amplitude/phase loop, amplifier amplitude/phase loop). Details on the design modifications, the high-power conditioning and the ramped commissioning are presented in this paper.
Taiwan Photon Source (TPS) had delivered the first synchrotron light on the last day of 2014. Installation of 16 beamlines of the first and second phases of TPS beamline project was completed. The third phase project also had been launched in 2021. To confront the situation that the experimental hall is more compact, we per-formed Computational Fluid Dynamic (CFD) simulation to analyse the effects of the air conditioning system and various heat sources to the temperature and flow fields in the experimental hall.
The ESRF-EBS is the first 4th generation source making use of the Hybrid Multi-Bend Achromat (HMBA) lattice cell, reaching an equilibrium horizontal emittance of 140 pm.rad in user mode (insertion devices (ID) gaps open). An off-energy operation was proposed to further reduce the equilibrium emittance by about 20 pm.rad. A first proposal rematched the HMBA optics at an energy deviation of -1\% and evaluated its dynamic aperture in the machine. Further experiments were dedicated to this study at the ESRF-EBS, including injection efficiency and lifetime optimisation.
The European Synchrotron Radiation Facility - Ex-tremely Brilliant Source (ESRF-EBS) is a facility upgrade allowing its scientific users to take advantage of the first high-energy 4th generation storage ring light source.
In December 2018, after 30 years of operation, the beam stopped for a 12-month shutdown to dismantle the old storage ring and to install the new X-ray source. On 25th August 2020, the user programme restarted with beam parameters very close to nominal values.
This paper reports on the present operation performance of the source, highlighting the ongoing and planned developments.
An electron cooler based on a storage ring is one of the options to improve the luminosity in the Electron-Ion Collider (EIC). The transverse emittance of the electrons in the cooler is driven by the quantum excitation in dipoles and wigglers, as well as by both beam-beam scattering with the ions and intra-beam scattering of the electrons in the regions with a non-zero dispersion. The resulting demand to minimize a dispersion conflicts with the need of a sufficient dispersion in sextupoles for chromaticity correction. We present a compromise between the two requirements.
One of the ways to measure beam optics in storage rings is to employ turn-by-turn (TBT) beam position monitor (BPM) data of transversely excited beams. In synchrotron light sources, such a technique is often not used, primarily because of the need for a lengthy BPM setup in spite of a significantly faster measurement. Beam optics is then inferred from orbit response matrix (ORM) measurement.
This paper demonstrates a solution to the BPM setup and measurements of optical parameters based on transverse and 3D-driven beam excitations in PETRA III. We also compare the optical parameters measured from TBT BPM data to those inferred from ORM.
In this paper, we present the possible use of laser Compton back scattering (CBS) to adjust and tune the bunch intensity. In the
future circular electron-positron collider “FCC-ee”, the intensity of the colliding bunches should be tightly controlled, with a maximum charge imbalance between collision partner bunches of less than 3–5%. The control of such tolerance is necessary due to the strong effect of beamstrahlung on the bunch length and “flip-flop” instability. We show a realistic beam optical line and simulation results of CBS in the "FCC-ee", including the distribution of scattered positrons.
The Electron-Ion Collider (EIC) presently under construction at Brookhaven National Laboratory will collide polarized high energy electron beams with hadron beams with luminosities up to 10^34cm^{-2}s^{-1} in the center mass energy range of 20-140 GeV. Preliminary beam-beam simulations resulted in an optimum working point of (.08, .06) in the Electron Storage Ring (ESR). However, during the ESR polarization simulation study this working point was found to be less than optimal for electron polarization. In this article, we present beam-beam simulation results in a wide range tune scan to search for optimal ESR design tunes that are acceptable for both beam-beam and polarization performances.
The observation of the Higgs boson by the LHC (2012), and the direct observation of gravitational waves (GW) from a collapsing binary systems by LIGO (2016) marked the successful end of long-standing efforts, and hopefully the dawn of a new era where both fields, Particle Accelerators (PA) and GW Physics, may benefit from knowledge/technologies developed by the other party. CERN recently hosted a meeting (SRGW2021) where such synergies were discussed, including the possibility of operating storage-rings/colliders as GW sources/detectors. Earth-bound interferometric GW detectors may explore only a tiny subset of the GW spectrum. Spaceborne detectors (LISA) and pulsar-timing observatories will open a window in the LF to ELF range, and different HF to SHF detectors have been proposed (SISSA2019). Observations at these frequencies would bring rich astrophysical/cosmological information. On the other hand, PA advances in superconducting magnets, and extremely high-Q RF cavities, and the (still controversial) possibility that superconductors may act as GW reflectors, suggest to reconsider the feasibility of a GW “Hertz experiment” based on Gertsenshteyn effect; while progress in (big) data analysis, control systems and optical materials from GW experiments may be useful for next gen PA. We review these ideas from a dual perspective, and highlight possible directions for common work.
NSLS-II is a 3 GeV third generation synchrotron light source at BNL. The storage ring was commissioned in 2014 and began its routine operations in the December of the same year. Since then, we have progressed steadily upwards in beam current and reached 500 mA in five years while increasing new insertion devices. Along this path, we report various challenges and the improvements to reach high current.
The community studying facilities to measure a possible Electric Dipole Moment of a charged particle (cpEDM) in a storage ring agreed that a Prototype Storage-Ring (PSR) is required as intermediate step to address critical questions, gain experience and rule out showstoppers. In what follows, a new lattice proposal of the PSR with a periodicity five is described and spin tracking simulations are shown. The main feature of this new lattice proposal is to use weak focusing quadrupolar components to achieve vertical stability while the horizontal optics properties are dominated by the focusing from the bending elements with a little impact from the quadrupoles.
The Synchrotron Light Source PETRA III is one of the core facilities at DESY offering each year more than 2000 users unique opportunities for experiments with hard X-rays of a very high brilliance. The light source is operated mainly in two operation modes with 480 and 40 bunches at a beam energy of 6 GeV. The availability and failure statistics is reviewed for the year 2022 in comparison with previous years. Studies at PETRA III are supporting the technical design phase for the planned upgrade PETRA IV. Several diagnostic devices have been tested and the installation of a cavity has been prepared. Furthermore, the operation of PETRA III at 5 GeV has been studied with the goal to reduce the electric power consumption of the accelerator. But a 5 GeV test run for all beam lines at PETRA III showed that this operation mode is impairing the experimental opportunities due to the lower brilliance and photon flux for hard X-rays.
Over the past few years, polarized bunch acceleration and store simulations have been performed in all five hadron and electron accelerator and storage rings of the future Brookhaven National Laboratory Electron Ion Collider: the AGS booster with an ac dipole, the AGS with partial snakes, RHIC with full snakes, possibly including its spin flipper, its EIC/HSR version w/ or w/o radial shift, on the hadron side, the electron RCS and ESR storage ring with spin rotators on the electron side, using stepwise integration techniques to push particles and spin, in virtue of, amongst other, their interest and accuracy regarding the treatment of Monte Carlo processes (synchrotron radiation for instance) and numerical integration of motion in magnetic field maps (Siberian snakes and other spin rotators, for instance). A brief overview of the exercises and their outcomes is given here.
To explore the beyond standard model of elementary physics, we proceed a new fundamental physics experiment, J-PARC muon g-2/EDM experiment. To realize very precise measurement of the muon spin precession frequency in the level of sub-ppm, a relativistic energy of muon beam is injected into a precisely adjusted storage magnet of sub-ppm uniformity by applying medical MRI magnet technologies.
Three-dimensional spiral beam injection scheme is intended to storage in 0.66 m diameter compact ring, we have carefully studied of a spatial distribution of a radial magnetic field of the storage magnet and required beam phase space, especially for a strong X-Y coupling. In this presentation, we will discuss about a strategy to precise control of the X-Y coupling at the beam transport line: how to detect X-Y coupling from a beam phase space, how to control X-Y coupling with eight independent rotatable quadrupole magnets. We also discuss about how to apply fine-tuning of the beam trajectory without disturbing the magnetic field in the beam storage volume, by use of active shield multipole coils.
Finally, we will report detailed studies of X-Y control at a demonstration beam line in KEK which proves the three-dimensional injection scheme is realistic one, as well as further challenges towards the original beam line at J-PARC.
The Korea 4th Generation Storage Ring(Korea-4GSR) project has been launched in 2022. The Korea 4GSR aims to generate the ultra-low emittance beam with the beam current of 400 mA and the beam energy of 4 GeV. In order to accelerate and store the beam to desired parameter, the Storage Ring RF(SRRF) is composed of 10 or more RF Stations and each RF Station includes LLRF(Low Level RF), HPRF(High Power RF), NCC(Normal Conducting Cavity) system.
For stable operation and machine safety, sub systems are operated by the Control System for the SRRF. In this paper, we describe the design of the Control System. It will include control network, operating interface, emergency interlock, data archiving and so on.
In the FCC-ee study, it is proposed that electron and positron beams circulate at high current and high energy in a 92-km circumference ring. The present operational scenario foresees a first running step at an energy of 45.6 GeV and around 1.4 A current, which would generate copious amounts of synchrotron radiation (SR) power and flux. To guarantee a quick decrease of the photon desorption yields and so a fast vacuum conditioning, it has been proposed to use localized SR absorbers along the vacuum chamber, spaced about 6 m apart. This would also help contain the high-energy Compton-scattered secondaries once the beam energy is increased up to 182.5 GeV, later in the experimental program.
In the preliminary design of FCC-ee vacuum chamber absorbers presented in this work, the SR thermal power is intercepted along around 100 mm of slanted surface. The temperature distribution in the adsorbers is estimated by Finite Element Analysis (FEA) and needs to be assessed to avoid any liquid-gas phase change within the water-cooling circuit. The cooling channels contain a twisted tape that increases the turbulence of water. This results in the desired heat transfer coefficient. The mechanical deformations due to the non-uniform temperature map are presented and analyzed as well.
Rapid cycling synchrotron (p-RCS) is the first synchrotron of the accelerator chain in the proposed Super Proton-Proton collider (SPPC) project. It will provide high-energy and high-power beams for the injection to the downstream accelerators for SPPC collision with the required beam characteristics such as bunch spacing, bunch population and emittance, but also serve independent application program with less restricted beam characteristics and a higher beam power of 3.4 MW. With a designed energy range of 1.2-10 GeV and a repetition rate of 25 Hz, the lattice design plays a mandatory role in beam dynamics. In this paper, three types of linear lattice for the p-RCS, which are based on the basic FODO module, triplet module and negative momentum compaction (NMC) factor module, respectively, are compared. Taking into consideration the longitudinal beam dynamics which requires as a large absolute of slippage factor as possible at the extraction energy, the NMC lattice is considered a preferable solution.
In this paper we will show the injection philosophy and the design of timing and filling scheme for high luminosity CEPC scheme under different energy modes. It is found that the RF frequency choice in CDR cannot meet the injection requirements for the bunch number at Z pole. A modified scheme was proposed to support the design luminosity,which basically meets our current design requirements and retains more flexibility for future high luminosity upgrade.
Since the upgrade and renovation of the East Experimental Area at CERN during Long Shutdown 2 (LS2: 2019 - 2021), demand has increased for slowly extracted beam from the CERN Proton Synchrotron (PS). The East Area is a multi-user facility carrying out a diverse experimental physics programme. It requires a wide range of slowly extracted beams to be delivered by the PS. This contribution summarises the gained understanding, progress and improvements made since LS2 in the slow extraction of both proton and ion beams. Furthermore, it describes the production of low intensity, variable energy, heavy-ion beams for a collaboration between CERN and the European Space Agency, striving to establish a novel and flexible high-energy heavy-ion radiation test facility.
We present an update on the design of the first Interaction Region (IR) for the the Electron Ion Collider (EIC) being built at Brookhaven National Laboratory (BNL). The EIC will collide high energy and highly polarized hadron and electron beams with a center of mass energy up to 140 GeV with luminosities of up to 10^34/cm^2/s. The first IR, located at IP6, is designed to meet the requirements of the nuclear physics community as outlined in [1]. A second IR is technically feasible but not part of the project.
The magnet apertures are sufficiently large to allow desired collision products to reach the far-forward detectors; the electron magnet apertures in the rear direction are chosen to be large enough to pass the synchrotron radiation fan. In the forward direction the electron apertures are large enough for non-Gaussian tails.
The paper discusses a number of recent recent changes to the design. The machine free region was recently increased from 9 to 9.5~m to allow for more space in the forward direction for the detector. We discuss the implications of this on the IR design and the physics acceptance. Another change which was implemented is the switch to 1.9~K for the superconducting magnets in the forward side, which helps crosstalk and space issues.
We report on progress developing the Energy and RF ramp for the EIC’s Rapid Cycling Synchrotron (RCS). The development of the RF voltage and phase ramp from injection energy at 400 MeV to 5, 10 and 18 GeV extraction energy requires control of the bunch’s longitudinal aspect ratio to avoid both collective instabilities, RF bucket height and width as well as lattice dynamic aperture limits. Further the ramp profile must meet the technical limits for the current super conducting cavity design.
A new ISOL rare isotope beam production facility, ARIEL, is being commissioned to triple the availability of radioactive ion beams for the ISAC experimental facilities at TRIUMF. Part of ARIEL is the new CANREB charge breeding facility that includes RFQ cooler, EBIS and Nier separator, and a high-resolution mass separator system (HRS). The HRS is designed to achieve a resolving power of 20,000 for a transmitted emittance of 3 µm with an energy spread of less than 0.5 eV for a beam energy up to 60 keV. The beam commissioning with stable ion beams was staged, using optical tunes developed for different mass resolving power: 5000, 10,000 and 20,000. Presently we are in the final development stage where we seek to reach the highest resolving power as per design, which requires correcting the high-order aberrations using our innovative and unique electrostatic multipole featuring an unconventional rectangular design. In this paper we are going to discuss issues encountered during the commissioning runs, and present recent results.
The LHC beam dump system was developed to safely and reliably dispose of the LHC beams at the end of physics fills or in case of emergency aborts. The beams are extracted by means of kicker magnets, deflecting the beams horizontally, and septa, which provide a vertical kick. The system must be able to cope with rare failure scenarios, such as an asynchronous beam dump, where the rise time of the extraction kickers is not synchronized with the 3 $\mu s$ long particle-free abort gap. This type of event would lead to bunches impacting on downstream accelerator equipment if not properly absorbed by a system of beam-intercepting devices. In the High Luminosity-LHC (HL-LHC) era, the protection absorbers have to withstand significantly higher bunch intensities of up to $2.3\cdot10^{11}$ protons. In this paper, we study the robustness and protection efficiency of the septum protection absorbers for HL-LHC operation. In particular, we present energy deposition simulations for the absorber blocks and downstream equipment and define the required absorber upgrades for HL-LHC.
The user service mode of ESRF started in August 2020 after the installation of the new EBS machine, replacing the original ESRF DBA storage ring. All the insertion devices (IDs) were stored and re-installed to be available from day-1 of the accelerator commissioning. A major concern was, and still is, to preserve them as much as possible from demagnetization, both low gap in-vacuum devices and in-air undulators. This paper presents the strategy put in place for the commissioning, and in a longer term over the first years of operation, to reduce the risk of radiation damage of the IDs.
PETRA IV is the 4th generation synchrotron light source upgrade of the PETRA III user facility at DESY in Hamburg. To minimise the disturbance of user experiments by the injection kicker pulse, the injection is planned to be realised as a single-bunch top-up injection with 4 groups of fast stripline kickers with 12 kicker modules in total plus one hot spare at every kicker group position. Due to the short bunch-to-bunch distance of 2 ns and a particle energy of 6 GeV, these kickers have to fulfill demanding requirements with respect to deflection pulse length, pulse rise and fall times, and kick strength. In this proceeding we review the current mechanical design after production of a first prototype and discuss measurements with the prototype in the lab as well as bunch deflection measurements.
The design of Southern Advanced Photon Source (SAPS), which is a 3.5 GeV storage ring based light source, has been actively updated in the past two years. In addition, many relevant research activities such as the development of an electron source, high gradient accelerating structures, RF cavities and power supplies for fast injection kickers have already been started. The updated overall design for SAPS will be introduced in this work, along with a brief overview of the on-going activities related to the project.
The High Energy Photon Source (HEPS) is a 6 GeV diffraction-limited storage ring light source being built in China. Basic accelerator physical design and vacuum design have been completed. Interactions between the accelerated particles and the residual-gas molecules will lead to a reduction in the beam lifetime. The residual gas lifetime includes contributions from elastic gas scattering and gas bremsstrahlung. To simulate the residual gas lifetime in the HEPS storage ring, the position-dependent gas pressure for various gas species is first evaluated according to the layout of the vacuum elements. And then simulations of the elastic gas scattering and gas bremsstrahlung at multiple locations are performed with gas pressure profiles using ELEGANT. This paper will present the residual gas lifetime and the particle loss distribution obtained by the multi-particle tracking method.
10Hz horizontal orbit oscillation due to helium flow was observed in the routine operation of the Relativistic Heavy Ion Collider (RHIC). Without compensation by 10Hz orbit feedback, this will cause sizeable luminosity variation and reduce the beam lifetime during physics stores. In this article, we revisit the effects of this beam oscillation with weak-strong beam-beam simulation and dynamic aperture calculation. The goal is to determine the tolerable 10 Hz orbit oscillation amplitude at the interaction region and we will use this tolerance determine the power supply ripple requirements in the Electron-Ion Collider (EIC).
The CERN Super Proton Synchrotron (SPS) aims at providing stable proton spills of several seconds to the North Area (NA) fixed target experiments via third-integer resonant slow extraction. However, low-frequency power converter ripple (primarily at 50 and 100 Hz) and high-frequency structures (mainly at harmonics of the revolution frequency) modulate the extracted intensity, which can compromise the performance of the data acquisition systems of the NA experiments. In this contribution, the implementation of Radio Frequency (RF) techniques for spill quality improvement is explored, with particular focus on empty bucket channelling. It is shown that both the main RF systems (at 200 and 800 MHz) can be successfully exploited to improve the SPS slow extraction.
We outline & summarise on what's known, best practices, and the state-of-the-arts for robust synchrotron light source design. I.e., model – analytical & numerical, robust design – higher-order-achromats, joint optimisation of the linear optics & nonlinear driving terms, tune confinement approach for the bare lattice, benchmarks & validation for the real lattice; which includes the impact of engineering tolerances & related control/corrections algorithms. In particular, using BESSY III as an example, a quantitative comparison is made with the state-of-the-arts for medium energy rings: MAX IV, SLS 2.0, and S. Leemann's higher-order-achromat proposal for ALS-U.
The hybrid multi bend lattice has been introduced with the ESRF EBS Storage ring. The scaling of such cell to accelerators of different sizes is not trivial. Several (not exhaustive) scaling rules that must be applied are reported and their performance is shown in terms of dynamic aperture and momentum acceptance of the resulting SR. A comparison of lattice cells with varying number of dipoles shows that the H6BA cell introduced in [*] is outperforming other layouts in all aspects.
The possibility of two interaction regions (IRs) is a design requirement for Electron Ion Collider (EIC). If implemented, the 2nd IR will be located in the existing RHIC experimental hall 8 facility and be in operation within the full energy range of ~20GeV to ~140GeV. With an addition of a secondary focus, the 2nd IR will add complementarity to the acceptance range of the 1st IR by expanding the detection of scattered particles with high longitudinal momentum. In this paper we provide an update on the current design status of the 2nd IR in terms of parameters, magnet layout and beam dynamics.
China Spallation Neutron Source (CSNS) is a high density complex with a high repetion rate of 25Hz. The Rapid Cycling Synchrotron is the key part of the CSNS. By adopting the sextupoles with pulsed beam power system, CSNS has been operating steadily at 140kW. The CSNSII is aim to deliever above 500kW with the upgrations of many aspects of the accelerator. The sextupoles upgration is very important for CSNSII. By optimization the location of the sextupoles with MOGA algorithm, the dynamic aperture of RCS is increased impressively. In this paper, we will review the operation status of the sextupoles and give some proposals about sextupole upgration plans.
The Proton Storage Ring (PSR) of LANSCE compresses the pulse of a linac-produced beam by a factor of more than 2000 into an ultra-short high intensity beam, making the Lujan Center a leading facilities in the delivery of instantaneous beam power. This short-pulse feature allows a variety of experiments from neutron science to fundamental nuclear physics. Further shortening the beam pulse by another factor of 2 is necessary to achieve high-resolution nuclear data the search for Beyond Standard Model particles. We will report on our current status in our research to simultaneously stack two shorter pulses into the PSR by repurposing existing components in a system that, unlike synchrotrons, has limited flexibility.
We propose a computationally efficient algorithm to calculate a single statistical realization of partially coherent synchrotron radiation fields at a given frequency. The proposed algorithm relies on a method for simulating Gaussian random fields. We cross-checked the algorithm’s consistency with other well-established approaches, and, in addition, we show its advantage in terms of computational efficiency. The algorithm exploits the assumption of quasi-homogeneity of the source. However, we show that it is applicable with reasonable accuracy outside of this assumption. This algorithm can be extended to other types of sources that follow Gaussian statistics beyond the assumption of the quasi-homogeneity. Finally, the demonstration of the algorithm is well-suited for educational purposes.
The High Energy Photon Source (HEPS), is an ultra-low emittance storage ring (USR) light source beingto be built in Beijing, China. Due to the characteristics of the compact 7BA structure with strong focusing, beam accumulation in an USR is expected to be very challenging. Our simulations confirmed the difficulty in the HEPS storage ring. This paper introduces the preparations made for the first-turns commissioning of the HEPS storage ring from the first injection to beam storage. The commissioning methods and simulation results for several key steps are discussed, including first-turns trajectory correction, RF parameters’ optimization, as well as tune measurement and adjustment in the first turns.
The High Energy Photon Source (HEPS) is a 6 GeV, 1.3 km storage ring light source being built in Beijing, China. To get an ultralow emittance, high-gradient quadrupoles, combined-function magnets and longitudinal gradient dipoles are adopted in the design of the storage ring and the lattice is compact. The impact of fringe field effects and cross talk between magnets is of interest. To this end, several methods based on one-dimensional and three-dimensional magnetic fields are used to model different kinds of magnets of the HEPS storage ring and the cross talk between magnets are simulated and evaluated. In this paper, we will introduce detailed modeling methods and the impact of fringe field effects and cross talk on the main parameters of the HEPS storage ring.
The Electron-Ion Collider (EIC) presently under construction at Brookhaven National Laboratory will collide polarized high energy electron beams with hadron beams with luminosities up to 10^34cm^{-2}s^{-1} in the center mass energy range of 20-140 GeV. To compensate the geometric luminosity loss due to a large crossing angle in the EIC, crab cavities are to be installed on both sides of interaction point (IP) to construct a local closed crabbing bump. However, for the current design lattice of the Hadron Storage Ring, the crab dispersion bump is not closed because the ideal 180 degree horizontal phase advance between the crab cavities on both sides of IP cannot be achieved. We carried out numerical simulations to evaluate the negative impacts with this imperfectly closed crab dispersion bump. We also simulated various schemes to close the crab dispersion.
The High Energy Photon Source (HEPS) is a 6 GeV diffraction-limited storage ring light source, which started construction in 2019. The sextupole and octupole magnets in the storage ring of HEPS are divided into several groups, and each group of magnets shares one power supply. In the lattice design, magnets in the same group are identical, but the real magnets have errors, which violate the symmetry of the lattice. To optimize the performance of HEPS, it is necessary to carry out sorting of these magnets. By doing simulations with elegant, we studied the effect of sorting on the performance of the nonlinear beam dynamics. The details are presented in this paper.
The possibility of spin control for dEDM experiment can be done by setting Wien Filters in straight section, which ensure that the particles spin retains mean direction in accordance with «Quasi-Frozen Spin» mode. However, the spin of different particles, due to their different motion in 3D space, in any case rotates with slightly different frequencies around the invariant axis, which one violates spin coherence. To ensure spin coherence, nonlinear elements, sextupoles, with a special placement on arcs must be used. Since sextupoles simultaneously affects the betatron chromaticity, we consider this complicated case.
The Electron Ion Collider calls for polarized proton and helion beams on polarized electron beam collisions. The placement of rotators in the Hadron Storage Ring is asymmetric relative to the interaction region, due to spacial constraints. This results in a spin tune shift as the rotators are ramped to their operating current. This spin tune shift is compensated for by ramping the snakes and is used in consideration for the number of snakes required.
Building new experimental facilities to house experiments is an expensive and time-consuming activity. Although usually less expensive, repurposing old experimental facilities to accommodate new ones has its own set of challenges with regard to obsolete equipment, adequacy of electrical power, radioactive shielding and cooling capacity. At Los Alamos National Laboratory (LANL), one such facility was previously used to provide a platform for Free Electron Laser (FEL) experiments that were completed 20 years ago. This paper explores the techniques and process to repurpose an existing experimental facility to accommodate the CARIE compact accelerator and the choices made to select and size equipment for success. Radio Frequency (RF) energy waveguide layout with vacuum calculation methods will be included as well as electrical power and radiation shielding requirements.
As the ESRF-EBS is running for two years, the Insertion Devices Laboratory is working to build new photon sources to allow the beamlines to take as much as possible profit from the new elctron beam properties. Among the variety of sources optimized depending on the beamlines applications, the low gap in-vacuum devices are essential. This paper presents the undulator field shimming methods used to maximize the undulator performances in terms of peak field, first and second field integrals, and phase error.
In recent years, high-gradient, symmetric focusing with active plasma lenses has regained significant interest due to its potential advantages in compactness and beam dynamics compared to conventional focusing elements. A promising application could be optical matching of highly divergent positrons from the undulator-based ILC positron source into the downstream accelerating structures to increase the positron yield.
In a collaboration between University Hamburg and DESY Hamburg a downscaled prototype for this application has been developed. Here, we present first plasma diagnostics results, such as discharge current stability, electron density distribution and reproducibility. Additionally, future plans for measuring the magnetic field distribution and a possible fullscale prototype will be discussed.
The construction of the first in-vacuum APPLE II undulator at HZB is progressing. The design of the IVUE32 employs a period length of 32mm, 78 periods, and a minimum gap of 7mm. The magnet structure has a force compensation scheme as proposed at SRI 2018 in Taiwan. Based on successful measurements of a prototype, new transverse slides fulfill all requirements with respect to stiffness, smooth operation, and UHV-compatibility due to the integration of a CF blade in one part of the slide. The delivery of the support and drive system including the new slides is expected for spring 2023. Various soldering and clamping options for a safe magnet fixture have been tested thoroughly in a 10-period prototype. The status of the undulator is reported particularly the results of the lifetime test in the 10-period prototype. The engineering layout of the RF-shielding, particularly the split foil will also be discussed. The design relies on detailed CST-simulations including geometric errors, as presented at this conference by P. Volz.
The collimation system of the electron-positron Future Circular Collider (FCC-ee) will have two main tasks: protect equipment from the multi-MJ beams and mitigate detector backgrounds. An integrated collimation system layout is presented, including beam halo collimation system in one insertion and synchrotron radiation collimation around the experimental interaction points. The Z-production operating mode is considered, which has a beam energy of 45.6 GeV and a stored beam energy of 20.7 MJ, making it the most critical one for machine protection. The collimation insertion optics, aperture model, and collimation configuration for this mode are presented. The beam loss cleaning performance of the collimation system is studied for selected beam loss scenarios using a set of novel tools that enable multi-turn tracking simulations.
A highly flexible synchrotron radiation source called Hybrid Ring (HR) is proposed at KEK [1]. In HR the storage (SR) bunches inside the ring and the single-pass (SP) bunches injected from the superconducting linac are coexisting. This feature allows for the unique experiments using both the synchrotron radiation irradiated from SR and SP bunches. Concerning the SP beam, the ultra-short bunch length of 50 fs, and the high bunch charge of 1 nC, are planned. Therefore, significant emittance growth and energy loss should be caused by the Coherent Synchrotron Radiation (CSR) emitted from the SP beam. For the feasibility study of the HR and the proper feedback to its design, the influence of the CSR in HR has been examined by the simulation analysis. We have performed the benchmark tests utilizing some simulation codes so as to check their region of applicability. The status and results of the HR will be presented in detail.
Optimization and realistic estimates of the sensitivity of the measurement of charged particle Electric Dipole Moment (EDM) in storage rings require a good understanding of systematic errors that can contribute to a vertical spin build-up mimicking the EDM signal to be detected. A specific case of systematic effect due to offsets of electrostatic bendings and longitudinal magnetic fields is studied. Spin tracking simulations to investigate whether this special case generates spin rotations, which cannot be disentangled from the ones due a finite EDM by combining observations made with both counter-rotating beams as predicted by analytical derivations, will be presented.
In the PETRA-IV storage ring, emittance growth due to the intra-beam scattering (IBS), as well as a short Touschek lifetime, are serious concerns. To mitigate such adverse effects, an active third harmonic cavity is applied to lengthen the beam bunches so that the particle densities at the core of the bunches can be reduced. However, if the RF buckets are filled with a non-uniform pattern, the beam could suffer from the transient beam-loading effect from the cavities' fundamental modes and leading to a bunch-to-bunch length variation. In this manuscript, we report the simulation study of the transient beam loading effect due to the fundamental modes of the double RF system in PETRA-IV by the code CETASIM developed in-house at DESY. With the periodic 80 bunch trains filling pattern, the peak-to-peak bunch length variation is around 30% compared to the ideal bunch lengthening condition; with the 7/8 filling pattern proposed recently, the bunch length variation is significantly modified by the transient beam loading effect and the guarding bunches at the head and tail of the bunch train can mitigate the transient beam loading to some extent
In this paper,we combines the problems in the determination of the adjustment weight of the current control network and the increasingly updated information processing model, taking the typical level network and making rational use of the function of MATLAB to systematically study the determination of the weight in the adjustment of control network.A variety of objective weighting methods are applied in the leveling network, the sub-method models are introduced in turn and the prior weighting methods such as entropy weighting method, coefficient of variation method, CRITIC weight method are applied in the leveling network combined by programming with actual engineering case to improve reliability. The determination of the adjustment weights of commonly used leveling control networks from the perspective of a priori confirmation of weights was studied by us, lays a foundation for the research on the reasonable weighting and data fusion of multiple types of observation data when using various measuring instruments such as DNA03,AT960 to establish leveling control networks in the construction of Hefei Advanced Light Facility.
The Superconducting Electron Accelerator Lab (SEALab)* is the SRF-accelerator physics research facility at HZB created in 2021 following official completion of the bERLinPro project. It provides opportunities for SRF-accelerator related research beyond the ERL program, yet ERL-related research continues in this facility (“bERLinPro@SEALab”).
The first stage of commissioning and operation will focus on the SRF injector, in 2022 mainly the SRF photo-injector. It is planned to study a wide range
of beam parameters from shortest pulses low charge regime applicable to e.g. ultrafast electron diffraction (“UED@SEALab”) to high charge and medium current
beam studies for ERLs, whether this may be for a light source or high-energy physics collider machine.
Here, we will mainly present the current status of the commissioning of the SRF photo-injector cryo module, the state of the Booster cryo module and plans towards a Linac allowing for a more sustainable and effective implementation of an ERL, including studies of fast reactive tuner implementation at 1.3 GHz for microphonics compensation and a potential test site for 4K operation of new SRF coating materials finally with beam.
SIS100 is a new superconducting heavy ion synchrotron optimized for the acceleration of high intensity heavy ion beams. Most crucial intensity limitation for heavy ion beams in SIS100 is the dynamic vacuum and corresponding beam loss by projectile ionization. Ionization loss and ion induced desorption drive the residual gas pressure into an instability, generating an intensity barrier at much lower intensity levels than any space charge limit. Technologies for stabilizing the dynamic vacuum, such as extensive charge separator lattice, pumping by cryogenic magnet chambers, cryo-adsorption pumps and cryo-ion catchers had to be implemented. SIS100 will also be the first user synchrotron comprising a laser cooling system for cooling at relativistic beam energies. Combined with a strong bunch compression system, laser cooling will support the generation of short ion bunches. Meanwhile, a large amount of the SIS100 components have been delivered and preparations for installation are launched. The shell construction of SIS100 underground tunnel is completed. Installation of the technical building infrastructure and the cryogenic distribution system are ongoing.
Horizontal collimators will be employed to protect the Advanced Photon Source (APS) Upgrade storage ring from full beam aborts. However, previous experiments[1] show the collimators themselves require additional protection from losses at full intensity. A vertically-deflecting fan-out kicker has been proposed to distribute the electron beam across the collimator, sufficiently reducing the locally absorbed energy density to maintain device integrity during beam aborts. Results will be discussed as available from the planned study in the present APS storage ring to evaluate this concept. The APS stored beam operating at 6 GeV and 200 mA (737 nC) and approaching APS-U conditions is used to irradiate both aluminum and copper collimator test pieces. Coupled simulations are used to determine possible damage that might occur on the collimator surface. As in previous work, loss distributions from elegant are employed as input to MARS to create dose maps that are, in turn, provided to FLASH to investigate hydrodynamic effects.
The CLS has moved to the ALBA/CLS DLLRF system in the booster ring. With the gained knowledge from this implementation we intend install to operate on the storage ring superconducting cavity with the goal to be in operation in 2024 comprehensive monitoring period.
The ALBA DLLRF system is based on the Nutaq PicoDigitzer. This system has been used on several normal conducting cavities, but not for superconducting. The application for SC will require special attention for hardware and software development.
The ultimate goal of studying spin-radial motion in a ring with "Quasi-Frozen Spin" is to develop a procedure for measuring the deuteron electric dipole moment. For a ring with a "Frozen Spin", the authors developed the Frequency Domain Method. A distinctive feature of a ring with a "Quasi-Frozen Spin" is spin oscillation with a small amplitude around the direction of motion. In this work, we study the influence of these oscillations on the final sensitivity of deuteron EDM search.
High Energy Photon Source is a 6 GeV diffraction-limited synchrotron light source currently under construction in Beijing. To provide the required 6 MV of RF voltage and 850 kW of beam power, five 166.6 MHz superconducting quarter-wave beta=1 cavities have been chosen for the fundamental RF system of the storage ring. Each cavity will be equipped with one fundamental power coupler (FPC) capable of delivering over 200 kW continuous-wave (CW) RF power. Based on the test performances of the two prototype couplers, formal couplers have been optimized, fabricated and high-power tested up to CW 250 kW in the traveling-wave mode and CW 100 kW in the standing-wave mode covering 16 phase points. Subsequently, one FPC was mounted on the first 166.6 MHz SRF cavity and participated in the horizontal high-power tests of the first cryomodule. The high-power test performances of the formal FPCs on the test bench and with the dressed cavity are presented in this paper, focusing on the effectiveness of the various design modifications compared with previous prototypes.
Beijing Electron-Positron Collider (BEPC-II) is a 1.89 GeV collider. There are two Superconducting (SC) cavities in the ring. A bandwidth close to 100Hz were found during the operation of the SC cavity, which influence the instability of the cavity frequency, and decreased the frequency control precise of the SC cavity. 500V bias input voltage were added on the Pizeo to produce longitudinal vibrations with frequency of 1Hz up to100Hz. With the same amplitude of bias voltage, the cavity has different response with different frequencies. 57Hz and 94Hz were found to be the dominant frequencies. The vibration were monitored on the liquid helium pipe and the cavity beam pipe during four processes (before and during the liquid supplying, after the cryogenic system give ready signal and with full power of the cavity). The preliminary results of the investigation will be presented in this paper.
The Elettra 2.0 upgrade project requires the realization of a new storage ring that will replace the existing one of Elettra. The Elettra 2.0 optic, developed on the basis of the magnet feasibility studies, include a total of 552 iron-dominated electro magnets, with all sextupoles and octupoles equipped with additional coils to achieve the combined fields of corrector and skew quadrupoles. This paper reports all the latest magnetic and pre-engineered designs and the comparison with the main magnet prototype performances.
The Southern Advanced Photon Source (SAPS) is a 4th generation storage ring based light source under design, which aims at providing electron beam with emittances below 100 pm.rad at the beam energy ~ 3.5 GeV. At present, two injector candidates are under consideration. One is a full energy Linac injector and the other is the popular injector which includes a low energy Linac and a full energy booster. The physics design of the booster in the popular injector is presented in the paper. The booster is a high intensity accelerator. Due to the high beam intensity, the impedance and corresponding collective instability may be serious issues which limit the highest beam intensity. The impedance model is estimated in the booster and the instability is predicted. The threshold intensity is bigger than the demand in the storage ring.
A new linear induction accelerator named Scorpius is being designed for multi-pulse flash radiography. The solid-state pulsed power system offers a technological breakthrough by delivering multiple independent pulses to accommodate a wide variety of pulse formats. The design provides pulse modulation capabilities which will mitigate reflected waves and reduce voltage variations across a temporal window twice as large as existing multi-pulse radiography accelerators. Successful coupling of the solid-state pulsed power with prototype induction cells has demonstrated these capabilities, and the project will assemble the Scorpius injector with a number of accelerating cells for integrated testing.
Non-steroidal anti-inflammatory drugs (NSAIDs) are commonly used medications to relieve pain and reduce inflammation. The motivation for studying NSAIDs is mainly based on their pharmaceutical applications. Three important NSAIDs, methyl salicylate (C8H8O3), fenoprofen (C15H14O3), and ketoprofen (C16H14O3), have been investigated in the gas phase. Gas-phase studies, where extrinsic effects are eliminated, provide unique advantages in exploring and characterizing the intrinsic electronic structure of the isolated molecules. Valence band (VB) photoelectron spectra, as well as core level carbon and oxygen 1s X-ray photoemission spectra, have been measured using the VG analyzer endstation at the GasPhase (GAPH) Photoemission beamline of Elettra-Sincrotrone Trieste, Italy. Results and their interpretation in the light of quantum chemical calculations will be presented.
Ground motion introduced by natural and civil sources affect the orbit in a storage ring. In order to predict the effect on the circulating beam, the knowledge of the amplification from ground to magnet movement as a function of frequency is required. This transfer function is most important for quadrupoles, since due to their distance-depended field strength they are the main source of orbit change when misaligned. PETRA III has mainly two types of lattice quadrupoles that however are placed on different support feet and ground compositions that affect the amplification or attenuation of certain frequencies. The transfer functions for a set of quadrupoles providing representative conditions have been measured and compared.
Matched first order transition crossing in the Relativistic Heavy Ion Collider (RHIC) is performed by using two families of jump quadrupoles when ramping species through transition to storage energy. The jump quadrupole families control $\gamma$ transition and the working point of the accelerator by compensating for the tune shift from the jump and minimizing optical distortions. After transition, amplitude and phase of the RF cavities need to be rematched to maintain constant acceleration. This configuration has proven to be effective in maintaining beam quality and reducing beam loss. The Hadron Storage Ring (HSR) retains the arcs and most of the insertion regions of RHIC. This paper discusses the gamma transition crossing of the HSR by the implementation of a matched first order transition jump.
We investigate the upgrade of Elettra 2.0 to radio-frequency transverse deflecting cavities generating a steady-state vertical deflection of selected electron bunches. The study demonstrates the feasibility of 1 to few ps-long x-ray pulses at MHz repetition rate provided simultaneously to several beamlines, and transparent to the standard multi-bunch operation. The short pulse exhibits total flux at 1-10% level of the standard single bunch emission, and transverse coherence preserved in both transverse planes up to approximately 0.5 keV.
We report on experimental investigations of a single electron, circulating in the Fermilab IOTA storage ring, focusing on two-photon undulator emissions. We employ a Mach-Zehnder (MZ) interferometer for the undulator radiation to determine the photon coherence length as well as to measure its statistical properties. In this experiment, the pulse of radiation in one arm of the interferometer is delayed by a certain optical delay. The optical delay can be adjusted with a step as small as 25 nm. We show that when the optical delay is varied, we observe oscillations of photon count rates in the two outputs of the interferometer. This interference pattern contains information about the temporal shape of the undulator radiation pulse, also known as the radiation coherence length. It may also contain information on non-classical two-photon statistics. In this paper, we present and discuss our measurements of this coherence length and statistical properties in both multi-electron and single-electron regimes.
The Diamond-II storage ring lattice has continued to be developed after publication of the Diamond-II’s technical design report. This study provides the updated information needed for the commissioning simulation. Firstly, changes to the reference lattice and phase-one insertion devices are briefly described. Then the error specifications are amended to be consistent with the magnet measurement and girder installation strategy. The commissioning strategy is revised accordingly with the associated errors. Finally, the commissioning simulations of multiple random machines are performed. Some of the statistical results are shown to justify the engineering feasibility of off-axis injection and beam accumulation with high injection efficiency.
The High Luminosity Large Hadron Collider (HL-LHC) is an ongoing project to upgrade the LHC, to increase the instantaneous luminosity by a factor of five compared to the nominal LHC. One of the driving factors to achieve this goal is an increase of the bunch population from 1.15e11 to 2.3e11 protons. This places unprecedented demands on the performance of the collimation system, which will need to be upgraded to fulfil the HL-LHC performance goals. In this paper, the planned upgrades of the collimation system and the performance of the system with proton beams is reviewed, taking into account some recent baseline changes. Tracking simulations in SixTrack in conjunction with FLUKA are used for the studies. The different cleaning scenarios considered are betatron cleaning, off-momentum cleaning and asynchronous beam dumps.
Located between the Delivery Ring and the Mu2e experiment in the Muon campus, the M4 beamline serves as the transport line for a resonantly extracted, 8kW, 8GeV pulsed proton beam to the Mu2e production target. In addition to challenges posed by elevation and directional changes, the M4 line is tasked with removing beam halo from resonant extraction and ensuring adequate inter-pulse beam extinction. A brief overview of the M4 line will be presented alongside on-going work to optimize halo collimation and minimize the radiological effects while maintaining adequate beam extinction downstream. An additional topic of the transport of the beam halo to the production target as a low-intensity beam for Mu2e calibration is also presented.
For storage ring light sources, photon flux, unlike the brightness, is almost free from the transverse beam emittance. To realize a high photon flux, as desired by spectrum analyzing or lithography, improving the stored current is an inevitable avenue. Facing the challenge of various instabilities in the low energy range, a 500\,MeV and 1000\,mA storage (UFT) is under design in Chongqing University of China. This paper presents the latest physical design results including lattice, dynamics, injection and instability.
The future Electron-Ion Collider (EIC) adopts a horizontal crab crossing scheme to compensate for the geometric luminosity loss from a 25 mrad crossing angle. The crab cavity noise-induced emittance growth in the deflecting plane (horizontal for EIC) has been well studied and a feedback system is effective to suppress the growth. However, simulations also showed emittance growth in the vertical plane when the beam profile is flat at IP. In this article, we will validate this observation and propose countermeasures to this emittance growth.
The SuperKEKB accelerator, a 7 GeV electron and a 4 GeV positron double-ring collider, is in progress in order to explore the new physics beyond the standard model.
The next milestone is to obtain integrated luminosity of 15 /ab data in the next decade,
so that the luminosity should exceed 2 x 10^35 /cm^2/s in several years.
One of the essential issues is the injection performances for both rings to be capable of storing beams of a few amperes due to overcoming their short lifetimes.
To preserve the emittance of the injection beam passing through the transport line is very important for the injection performances.
However, the large emittance growths have been observed in the both of electron and positron beam transport lines.
After many efforts on the research this issue from both sides of the simulations and measurements,
finally the coherent synchrotron radiation (CSR) wakefields has gotten to be suspected as the cause of the emittance growths.
According to the parallel conducting plates model, CSR wakefields are reduced when the beam passes through the offset position from the median plane surface of the plates.
In this study, it will be reported that the measured emittance variation of the injection beam with the bump orbit at the arc section of
transport line for the SuperKEKB 7 GeV electron ring.
The Large Hadron Collider (LHC) arcs have been designed for a FODO optics with roughly 90° betatron phase advance per arc cell, but not necessarily with exactly the same optics in the eight sectors of the ring. Measuring an optics with a significantly different arc cell phase advance, e.g. 60° which is at the limit for aperture at LHC injection, offers the possibility of understanding the LHC in an unprecedented depth. Furthermore, this optics would allow the beam energy to be pushed even further, since the required magnet settings are lower than for the standard 90° optics for the same beam energy. Such an optics has therefore been designed, respecting all constraints for one low intensity pilot bunch per beam, and tested during commissioning of that latest LHC Run. First measurements, performed only for one beam at injection, are presented and compared to results obtained for the nominal 90° optics.
750 MHz IH-DTL with the capability to accelerate protons from 3 to 10
MeV was proposed for the compact therpy linac that now under development in IMP. Four drift tube sections were housed in a single vacuum chamber and coupled with three large drift tubes which housing focusing triplet lens inside. In each drift tube section, there were 9 to 10 drift tubes, supported by the separated ridges. This cavity will be powered by a 1 MW klystron at 0.1% duty cycle, the kp factor is about 1.7 at the operation power level. The tank is now under construction and expected to be ready for beam commissioning in the middle of 2023. The overall cavity design and the status of the power cavity are presented in this paper.
After the PIP-II linac is commissioned as a new start of the Fermilab Acclerator Complex, the Booster will become a bottleneck for future high intensity particle physics research at Fermilab. An SRF linac is proposed as a replacement for the booster to enable future higher power proton beams in the Fermilab complex - this would include neutrino-based and muon-based studies, dark matter searches, and a platform for R&D for a muon collider. In this contribution, we overview the early conceptual accelerator design under development and discuss potential configuration options.
Production of super heavy elements of which atomic number is larger than 118 can provide new prospects in the field of nuclear physics. Extremely low production rate of these elements makes the experiments time consuming. This difficulty can be solved by using the energy recovery internal target, so-called ERIT, because the number of interactions can be increased as a circulating beam hits the target located in the ERIT ring. Here, we present a conceptual design of the FFA ring for super heavy element production adopting the ERIT mechanism.
To reach the desired energy for a muon collider, muons should be accelerated to 5 TeV. This acceleration must be rapid to avoid muon decays, while simultaneously having a high average bending field to minimize the the required RF voltage. One concern with high energy muons is radiation from neutrinos, produced from muon decay, interacting with matter far from the accelerator. While this is less of a concern for acceration than for the collider ring, maximizing the number of straight sections in the acceleration ring would minimize this radiation. Doing so requires minimizing the length of the arcs while maintaining zero dispersion through the RF cavities. The most compact cell that would accomplish this would be a double bend achromat (DBA). I present a double-bend achromat lattice cell for muon acceleration in a hybrid pulsed synchrotron. "Hybrid" refers to the use of a mixture of superconducting fixed field magnets and bipolar pulsed warm dipoles to maintain a high average bending field. The design considers the required magnet aperture for the beam size and an estimate for shielding. I will discuss the longitudinal dynamics for this design.
I describe a fixed field alternating gradient (FFA) lattice design to accelerate muons final energy for a muon collider. Ideally the muons would be accelerated to 5 TeV to reach the desired energy for physics studies*. An FFA allows the acceleration of muons over a large energy range without changing magnetic fields. It is an alternative to a pulsed synchrotron in which magnet fields must be varied very rapidly to minimize muon decays. I present a design for a linear non-scaling FFA which is optimized to minimize the required magnet fields. That optimization target is chosen since magnet fields are limited by magnet technology, and those technological limits will therefore limit the energy reach or bound the minimum size of the accelerator. I consider a design that would fit on the Fermilab site as well as a design with an unconstrained but minimized size. I compare the FFA design to a pulsed synchrotron design with similar technology limitations. I discuss longitudinal dynamics for acceleration, benefits of adding nonlinearity to the magnets, and the challenges of extraction from the FFA ring.
Betatron coupling resonance has been considered by many low emittance upgrade light sources as a candidate to produce round beams. Due to the limited literature on the topic, last year an experimental campaign was undertaken on the ALBA storage ring to establish limits and requirements to operate a light source in full coupling. The work highlighted how coupling can indeed produce a round beam with certain easiness but not free from shortcomings: the fractional betatron tunes must be set equal, resulting in a substantial constraint to the optics and requiring a sophisticated control of the optics itself in order to keep the resonance condition despite the movement of insertion devices and drifts.
To work around these limitations, this year a different approach, based on the excitation of the coupling resonance with an A.C. skew quadrupole was tested. A first experiment was attempted by converting the existing tune excitation stripline into a skew quadrupole, but the limited available power allowed to produce only a barely perceptible coupling. The stripline was then turned into an electric deflector by removing the resistive terminations and allowing to drive the electrodes to higher voltage. Here the newly obtained results with the A.C excitation are presented.
New R\&D concepts for particle acceleration, generation, and focusing at ultra high acceleration gradients (GeV/m and beyond) have the potential to enable future e+e- and $\gamma - \gamma$ colliders to and beyond 15 TeV energies. In addition to proven high gradient and ultra-bright beam generation, these systems have the potential to increase luminosity per unit beam power via short beams, for practical energy recovery to extend the reach of high energy physics, and for fast cooling. They hence have potential to reduce the dimensions, CO$_2$ footprint, and costs of future colliders, with added potential to reduce power consumption. The last decade has seen tremendous experimental progress in performance, together with development of concepts to address potential collider issues. Conceptual parameter sets for colliders have been developed for e+e- and $\gamma \gamma$ colliders at a range of energies, which present potentially competitive options with prospects for future cost reduction. In addition to a strengthened ongoing R$\&$D program, continuing to develop these collider concepts in interaction with the collider and high energy physics communities, starting with an integrated set of parameters, is important; as is development of technologies through nearer-term applications. Progress in these concepts, next steps, and results of Snowmass Accelerator Frontier topical group # 6, Advanced Accelerator Concepts (https://doi.org/10.48550/arXiv.2208.13279) will be discussed.
The performance of the Low Energy Ion Ring (LEIR) at CERN is mainly determined by the number of charges extracted from the machine and transferred to the downstream chain of accelerators. While the required target of 9e10 charges has now been surpassed, a series of studies have been undertaken to further push the intensity reach of LEIR. In this work, we quantify the effect of the stray fields generated by the adjoining Proton Synchrotron (PS), which were recently partially shielded, and the effect of the stripper foil in the Linac supplying LEIR with its ions, Linac 3. The impact of the stray field was measured by observing the variation in injection trajectory, while that of the stripper foil was determined from the evolution of the Schottky energy profile in LEIR. Models have been developed to extrapolate the impact of these effects to the injection efficiency of LEIR, and consequently to the extracted beam intensity.
Electron beam central-axis percentage depth dose (PDD) curves in water phantom are routinely employed to evaluate the electron beam energy at the phantom surface, in particular the mean and most probable energies from the values of R50 (half-value range) and Rp (practical range). However, these two quantities are not enough to evaluate important details of the energy distribution, such as the FWHM (Full Width Half Maximum) and the possible presence of a low-energy tail. This paper presents a numerical method that allows estimating the shape of the energy spectrum from a PDD curve. The algorithm uses a database consisting of a set of depth dose curves for monochromatic beams computed by FLUKA in the range 0.1-6.0 MeV by steps of 0.1 MeV and, using an adaptive iterative Monte Carlo process, reconstructs the incident energy spectrum by minimizing the distance between the measured PDD and the computed one. Applications of a MATLAB code based on this algorithm to simulated and real measurements of electron beams done at APAM lab (ENEA Frascati) are presented. This approach represents a strong simplification with respect to energy analysis based on the use of a magnetic spectrometer.
While large circular colliders rely upon analysis of turn-by-turn beam trajectory data to infer and correct magnetic lattice imperfection and beam optics parameters, historically storage-ring based light sources have been exploiting orbit distortion, via the orbit response matrix. However, even large collider usually benefit of the orbit analysis during the design phase, in order to evaluate and define tolerances, correction layouts and expected performances. The proposed FCC-ee is no different, though its length (about 100 km) and amount of magnets (about ???) make the standard closed-orbit analysis time consuming. We applied new analytic tools to cope with this issue, showing a significant gain in computational time with practically no loss of accuracy. Examples of applications to the ESRF EBS storage ring and to the CERN FCC-ee are reported with an outlook to an additional challenge provided by the FCC-ee.
Iterative learning control(ILC) is a effictive algorithm for transient beam loading compensation. However, considering the algorithm complexity and the hardware cost, the ILC algorithm is usually implemented outside FPGA. This practice would decrease the real-time ability of the control system. In this paper, a real-time ILC algrithm will be introduced. And the result is summarized.
All beam dump events at the Large Hadron Collider (LHC) are analysed in detail to verify the correct functioning of the Machine Protection System and to allow the early identification of potential issues. This includes the manual evaluation of the measured particle losses at the moment of the beam dump event by machine-protection experts.
Recently, a model for automated beam-loss evaluation has been developed. It is based on the careful analysis of previous proton losses during Run 2 of the LHC (2015-2018). To distinguish expected losses during the beam dump event from abnormally high losses, individual thresholds for more than 3700 Beam Loss Monitors have been derived.
The paper describes the cleaning and post-processing of the required data and explains the computation of the beam-loss thresholds. It then reviews the performance of the automated loss evaluation and discusses its potential for future operational use.
RF-Conditioning of a room temperature cavity is a long and resource intensive process. The need for constant supervision by experienced personal to avoid damage to the cavity and used equipment makes it a very expansive endeavor. To reduce the workload of the experimentalist, it was decided to develop a program utilizing machine learning, which, once finished, should have the probabilities to greatly reduce the need for constant supervision by human personal or even to conduct a full RF-conditioning on its own. After a training with existing data of already conducted conditioning of room temperature cavities and a virtual cavity, it is planned to improve and expand the program during the RF-conditioning of 15 CH-cavities, designated for the MYRRHA project, with similar properties. In this paper, the outline of the program, as well as the existing and planned goals shall be given.
We fabricated corrugated wakefield structures and did cold test of them. Since the wakefield frequency of our structure is about 0.2 THz, there are several technical issues in the bead-pull.
We present issues concerning to bead size and the wire. And issues concerning to mode converter are described as well. We manufacture a customized mode converter which change electromagnetic mode from rectangular TE10 to circular TM01. The biggest issue was not only the TM01 but also the TE11 excited. So we suggest a method of extracting only the results by TM01. And the operating frequency of the wakefield structure was calculated with this method. The operating frequency by cold test matched well with the simulation.
The baseline beam parameters of the FCC-ee contemplate different operation modes, with beam energies ranging between 45.6 GeV and 182.5 GeV. The highest expected beam stored energy reaches 20 MJ for the so-called Z operation mode (45.6 GeV), i.e. two orders of magnitude above that found in previous and operating lepton colliders.
In order to protect sensitive equipment and to limit background to the experiments, a two-stage collimator system is planned to be implemented.
Considering that collimator materials need to have a relatively low density in order to minimise the energy density deposited by the beam, the active length of the jaws would be relatively high (30-40 cm); hence, producing a significant impact on the impedance of the machine.
For this reason, materials with high electrical conductivity are to be considered. Another important property is thermal conductivity (to be able to dissipate the heat deposited by the beam).
A preliminary study of energy deposition and thermal stresses in different candidate materials for primary collimators is presented here.
The Beijing Electron Positron Collider II will upgrade to achieve a higher beam energy and higher luminosity which need a higher beam current and smaller beam size. The consequent high beam background should be controlled within in a safety range. The beam related background at BEPCII is mainly from the Touschek effect and the beam gas effect. This paper presents the beam background study at BEPCII, which includes the recent results of experiment and simulation.
The machine-detector interface (MDI) issues are one of the most complicated and challenging topics at the Circular Electron Positron Collider(CEPC). Comprehensive understandings of the MDI issues are decisive for achieving the optimal overall performance of the accelerator and detector. The CEPC machine will operate at different beam energies, from 45.5 GeV up to 180 GeV.
A flexible interaction region design will be plausible to allow for the large beam energy range. However, the design has to provide high luminosity that is desirable for physics studies but keep the radiation backgrounds tolerable to the detectors. In this paper, the latest design of the CEPC MDI based on the TDR draft will be presented, covering the following topics:
The design of the beam pipe, which would foresee several constraints: In the central region (z = ±12 cm), it should be placed as close as possible to the interaction point and with a minimal material budget. But it should still stay far away enough not to interfere with the beam backgrounds.
The estimation of beam-induced backgrounds. A detailed simulation covering the main contributions from synchrotron radiation, pair production, and off-momentum beam particles has been performed.
The suppering/mitigating schemes. A preliminary design of the collimation scheme has been studied, including the position, material, shape of the collimators, and also the effectiveness of them.
The design of the electron-positron collider, FCC-ee, is being optimised within the framework of the Future Circular Collider Feasibility Study. Achieving the design performance requires a well-controlled orbit. SuperKEKB has recently observed that temperature drifts during high intensity operation shift the transverse position of sextupoles by around 10 µm, introducing significant optics aberrations, something that also to be considered in the FCC-ee design. Beam based alignment and optics correction techniques are explored here to improve the tuning performance and mitigate potential drifts during operation.
There is a plan in the Canadian Light Source (CLS) to replace the current Linac with a new one from Research Instruments GmbH in mid 2024. To have a better insight to the current and future Linac beam parameters and to optimize the LTB(Linac-To-Booster) beamline parameters, the beam twiss parameters, energy and energy spread should be measured. A quad-scan method is used to measure twiss parameters. Energy and energy spread is measured by using the first dipole of the LTB 90 degrees achromat beamline. This LTB achormat beamline is upgraded with a new screen station and one BPM. This BPM and two other BPMs before the LTB achromat beamline used for a non-destructive energy measurement and will be a part of the active energy correction system. In this paper, we will report the most updated measurement and the diagnostic system upgrades.
Energy recovery of residual ions may be needed to increase the energy efficiency of Neutral Beam (NB) injectors for fusion plants as DEMO while a deflection-based system has been proposed. A compact beam energy recovery system, composed of 2 Farady Cups (FC) with holes for D0 passage, based on space charge effects, very effective to recover ions with low residual energy, has been proposed recently to replace the Electrostatic Residual Ion Dump (ERID) designed for ITER to dump the residual D- and D+ before the NB injection in the tokamak plasma [1]. New more accurate simulations on the proposed recovery system, however, presented some collection efficiency problems for very high initial beam kinetic energy (Eki=0.5÷ 1 MeV) when a very low residual (few keV) energy in the planned device. In this contribution, all parameter tunings for optimized simulation results are described and discussed. The collection of high Eki ions at low energy (a few percent of the full neutral beam energy Eki) remain possible although it could be done with lower efficiencies.
A high-charge, low-emittance injection beam is essential for SuperKEKB. For its both rings, HER and LER, the injection efficiencies and detector backgrounds have not been good enough up to the recent run. There are many reasons for the issues. For example, serious emittance growths are observed through the beam transport lines between the injector linac and both rings. It is considered that some parts of them are due to coherent synchrotron radiation as the observed horizontal emittance blowups depend on the bunch charge. Especially for the HER injection, physical aperture around the injection point and ring dynamic aperture also contribute, as both are narrower than the design.
In this paper, we discuss the injection issues up to 2022 operation and outlook for the future to maximum collision currents.
In the electron-driven ILC positron source, the positron is generated a multi-bunch format with gaps, because it corresponds to a part of the damping ring fill pattern. The beam loading is compensated by amplitude modulation on the input RF (*). In this article, we derive the exact solution for the compensation with gaps. In addition, we evaluate the effect of the time constant (delay) of the input RF modulation due to klystron Q-value.
In the future 100 km-scale Circular Electron Positron Collider (CEPC), beam polarization is an important design aspect. Transverse beam polarization for resonant depolarization is essential for precision measurements of the beam energies at Z-pol and WW threshold. Longitudinally polarized colliding beams are also beneficial for expanding the capability of the physics program. This paper reports the progress in the design studies of polarized beams for the CEPC. We focus on the approach of injection of polarized beams generated from the source into the collider rings for both applications. Our investigation into key issues in this approach is summarized, including polarized positron beam generation, beam polarization maintenance in the booster, and spin rotator design in the collider rings. Implications to resonant depolarization measurements are also discussed.
The understanding of beam-beam effects, which influence the choice of the FCC-ee design parameters in several aspects, require sophisticated and high-performance numerical simulations. The self-consistent study of the interplay of several nonlinear dynamical phenomena resulting from collisions in the machine is key to accurately assess its potential performance. Although current simulation frameworks can address specific aspects of the dynamics separately, they are difficult to interface with each other for more complex studies. To address this challenge, Xsuite, a new general purpose software framework for beam dynamics simulations, is currently under development. We discuss the implementation of the beam-beam interaction in this new toolkit and the evaluation of its performance on multiple platforms.
For the Future Circular Collider (FCC-ee), particular attention is drowned to the crucial role of the positron source. Two positron production schemes are considered for the FCC-ee: conventional and crystal-based (hybrid), implying the use of channeling radiation in the oriented crystals. To design and optimize the positron production and capture by considering the positron injector parameters, including the electron drive beam and the final system acceptance, a start-to-end simulation toolkit should be developed.
This paper will present the first results of benchmarking the FCC-ee positron source simulation tools using the SuperKEKB positron source currently in operation. The model starts with the production of positrons and target studies in Geant4. Then, a new tracking code RF-Track is used for capturing and tracking the generated positrons through the capture section composed of the matching device and several accelerating structures embedded in the solenoid field to accelerate the positrons until ~120 MeV. Afterward, the positrons are further accelerated to the energy of the Damping Ring (1.1 GeV).
The measurement of Bhabha scattering photons enables to directly estimate luminosity in lepton colliders. Currently existing Monte Carlo event generators for this process are optimized for high precision detector background simulations. From a beam dynamics point of view, the emitted photons will modify the bunch distribution and lead to beam losses due to the limited momentum acceptance of the machine. Hence the interest in building an event generator which is optimized for beam dynamics studies requiring efficient multiturn tracking simulations. We discuss the implementation of such a model in the newly developed Xsuite simulation framework as well as its benchmark and performance.
We carried out the study of the beam lifetime at SuperKEKB to investigate beam instabilities. We analyzed the injection interval for individual bunches to evaluate their beam lifetime ratio. SuperKEKB performed the top-up operation with the equalized bunches currents. This particular condition enables us to evaluate the lifetime ratio among all operation bunches. This report introduces the analysis results for the 2020 and 2021 data. We observed the beam lifetime has dependent on the bunch spacing and the relative position in the bunch train. Besides, in the December 2021 data, we determined the magnitude of the forward/backward asymmetry of the lifetime in the bunch train depends on the bunch current. They become good hints to understand the beam instabilities such as the electron cloud, the ion cloud, the beam-beam
effect in the collision, and so on.
I describe the method used for calibration the amplitudes and phases of the cavities in the Main Linac Cryomodule (MLC) for the CBETA energy recovery linac at Cornell University. The cavities are powered one at a time, and the phase of each cavity is set to a uniformly spaced set of values over a full 360 degree range, with cavity voltages set to one or more values. For each cavity, voltage, and phase, arrival time measurements are taken at BPMs upstream and downstream of the linac. No magnets lie between the linac and the BPMs. These measurements are used to obtain a least-squares fit the parameters of a model. The model is based on integrating through a fieldmap that was generated from a finite element computation. The parameters to be fit are the scaling factors between the programmed and actual cavity voltages, the offset between the programmed and actual cavity phases, and the the energy of the beam coming into the linac. The fitting process is accelerated by constructing a good initial guess for the parameters, and by computing the arrival time and its derivatives to the parameters so that Newton's method can be used to solve for the fitting parameters.
Extending CEBAF energy reach by increasing the number of recirculations, while using the existing SRF system is being explored. Proposed energy upgrade is based on a new approach to multi-pass acceleration of electrons in a single Fixed Field Alternating Gradient (FFA) beam line, configured with Halbach-style permanent magnets. Encouraged by recent success of CBETA, a proposal was formulated to nearly ‘double’ CEBAF energy by replacing the highest energy arcs with a pair of FFA arcs. The new non-scaling FFA arcs would support simultaneous transport of additional 6 passes with energies spanning a factor of two. One of the challenges of the multi-pass (11) linac optics is to assure uniform focusing in a vast range of energies, in a fixed field lattice. Here, we propose a triplet lattice that would provide a stable periodic solution covering energy ratio of 1:33. The current CEBAF injection at 123 MeV, makes optical matching in the first linac virtually impossible due to extremely high energy span ratio (1:175). Replacement of the current injector with a 650 MeV recirculating injector will alleviate that problem. Orbital and optical matching from the FFA arcs to the linacs is implemented as a compact non-adiabatic insert. Presented scheme would promise to deliver a 22 GeV beam with normalized emittance of 76 mm·mrad and with a relative energy spread of 1×10-3. Further recirculation beyond 22 GeV is limited by large, 974 MeV per electron, energy loss due to synchrotron radiation.
The CEPC is a proposed high luminosity Higgs/Z factory, with the potential to be upgraded to top factory at center-of-mass energy of 360GeV. We perform an optimization study on the circumference of CEPC. We calculate the instant luminosity, the construction and operation cost for different circumferences. With respect to the total cost and average cost per particle, we conclude that the optimal circumference for the CEPC Higgs operation is 80 km. Taking into account of the Z pole operation, the potential high-energy upgrade of CEPC (top factory), the optimal circumference increased to 100 km. The long future proton-proton upgrade of CEPC (SPPC) also favors a larger circumference, and we conclude that 100 km is the global optimized circumference for this facility.
A damping ring system which includes a small 1.1 GeV ring and two transport lines is introduced in CEPC linac in order to reduce the transverse emittance of positron beam at the end of linac and hence reduce the beam loss in the booster. The repetition rate of Linac is 100 Hz and one-bunch-per-pulse is considered. The double-bunch scheme of Linac is only considered for the high luminosity mode at Z pole. The positron beam is generated by 4 GeV electron beam hitting tungsten target and then is captured by an AMD flux concentrator. Each positron bunch is injected into damping ring every 10 ms and two bunches are stored in the ring so that the storage time for each bunch is 20 ms. The bunch number in the damping ring can be increased to 4 with an upgrade and hence the storage time for each bunch can be increased to 40 ms. The reversed bending magnet scheme is adopted for TDR in order to reduce the emittance significantly. The normalized emittance of positron beam is expected to be reduced from 2500 mm.mrad to 166 mm.mrad (or 97 mm.mrad) in the damping ring.
The future upgrade to the High-Luminosity Large Hadron Collider (HL-LHC) will impose tight tolerances on IP optics measurements. k-modulation is currently the preferred method in the LHC for IP optics measurements and will play a critical role in the HL-LHC. As such, Run 3 of the LHC provides an ideal test-bench for addressing challenges in k-modulation. In the first commissioning year of Run 3, this method was used to measure and validate optics with beta ranging from 30cm to 24m. However unsatisfactory reproducibility was observed for low beta measurements. This paper presents the k-modulation results for the start of Run 3 with in depth analyses and it highlights the sensitivity of this method in view of the challenging HL-LHC runs.
I describe a method for finding a set of cavity voltages and phases for the CBETA multi-pass energy recovery linac. The beam in CBETA makes up to 8 passes through its 6 cavity linac. The voltage and phase for each cavity can be set individually, and the path length for each arc energy can be set as well. I show that solutions can be found where each cavity has energy gains and losses balanced and all of the arc energies are precisely their design values. There are multiple families of solutions characterized by where the beam is with respect to the linac crest on each pass. I will choose the solution family that reduces the amount of energy spread generated by the beam going through cavities off-crest. I will plot solution parameters as a function of the effective linac phase (which I will define) for the first pass, and show that a given solution family can be found only for a certain range of that first pass phase.
The Compact Linear Collider (CLIC) is a proposed linear accelerator designed to collide electrons and positrons at energies up to 3 TeV. In order to explore new physics and to be more competitive with other collider projects, CLIC is exploring the increase of the center-of-mass energy to 7 TeV. The CLIC Beam Delivery System (BDS) transports the lepton beams from the exit of the Main Linac to the Interaction Point (IP). This paper reports on the studies and the challenges of the new BDS design, such as minimizing the extent of trajectory bending for collimation and chromaticity correction to reduce the effects from synchrotron radiation, ensuring a good transverse aberration control at the IP.
Magnetic fields in the 12-16 T range are needed to bend the beams in future hadron colliders, such as the CERN FCC-hh. For these magnets, made with Nb3Sn superconducting cable, a small reduction of the field brings a non-negligible reduction of cost and complexity. Increasing the dipole filling factor is hence a priority to provide higher energies for the same magnetic fields - or the same energies for lower magnetic fields. To this aim, the use of combined-function magnets is proposed to design the ring lattice in place of the standard separate-function solution. The properties of the combined-function solution and of the magnets that would be needed for the FCC-hh are presented and discussed in detail in this paper.
Hollow electron lenses (HELs) could be used in the HL-LHC to selectively remove halo particles from the circulating beams. While the ideal design should leave particles in the beam core unaffected, in reality, the core particles will be exposed to a small residual kick that could induce transverse emittance blowup if not properly compensated while the HEL is operated in pulsed mode. One possible solution would be to couple the HEL pulse with the adjacent HL-LHC transverse damper (ADT). The principle consists of exerting an oppositely directed kick with the ADT at each turn the HEL is switched on, thus compensating the HEL residual kick on the beam core. In this contribution, we simulate the performance of this compensation scheme and possible commissioning scenarios, aiming at reliably setting up the compensation scheme when the direction and amplitude of the residual kick are, a priori, unknown.
The interaction of particle beams with materials plays an increasingly important role in the design of beamlines, as it causes particle scattering, energy loss and energy straggling processes to occur. Such interactions are relevant in high-precision applications such as radiation oncology treatment planning, where the beam travels through air before reach- ing the patient, and are also the crucial mechanism for ionization cooling processes, such as those required for generating high-brightness beams for muon colliders. Few particle tracking codes integrate such effects in an environment suitable for optics calculations and multi-objective optimizations. This work presents the simulation of these effects in the beam tracking program RF-Track, compares the beam-matter interactions with similar tracking programs and discusses the results.
Muon colliders are promising machines that may enable future new discoveries in particle physics through the fundamental properties of the muon and negligible synchrotron radiation. Muons result from a hadronic shower arising from a proton beam striking a target. These muons occupy a huge phase space area that has to be cooled down. One of the major challenges for muon colliders is the final cooling channel, a design that consists of a semi-periodic structure of high-field solenoids with absorbers and re- accelerating RF-structures in between. After losing tens of MeV in each absorber, the rapid re-acceleration of muons requires high gradients and low frequencies in the RF- system. Previous studies suggest induction linacs for re-accelerations due to the strong growth of the longitudinal emittance towards the end of the final cooling channel. This work proposes an alternative technique using a multi-harmonic radio frequency system and discusses its properties and performances.
The Configuration Management of the LHC and its injectors ensures a clear and coherent representation of the CERN accelerators at a given point in time. It has been evolving steadily. The methodology has been continuously improved, incorporating best practices and was also extended to the injectors to face the Long Shutdown 2 (LS2) with a set of rigorous and homogenised processes for the entire accelerator complex. Lessons learnt from the LS2 provide a strong basis to further improve the effectiveness of the change management process.
This paper describes the action plan, concerning the processes and engineering tools, to further improve configuration management efficiency to face the numerous changes foreseen during the Long Shutdown 3 (LS3), with principally the equipment installation foreseen by the HL-LHC project. In addition, it reports on the smooth transition between the LHC and HL-LHC configuration teams to ensure the long-term operation and maintenance of the LHC.
Crystal collimation is studied to improve the collimation efficiency with ion beams at the High-Luminosity Large Hadron Collider (HL-LHC). Bent crystals are used instead of conventional primary collimators to deflect high-energy halo particles at angles orders of magnitude larger than what can be achieved with scattering by conventional materials. Following the promising results obtained during Run 2 (2015-2018), this collimation technique is planned for LHC operation with heavy ions already during Run 3, starting in 2023, to mitigate the risk of magnet quenches from beams of higher energy and intensity. Tests with low-intensity proton beams are extremely important to characterize the crystal collimator hardware, assess the performance and investigate other operational aspects in preparation for the ion run. This paper presents the results of tests carried out in 2022 with proton beams at the record energy of 6.8 TeV.
DAFNE, the Frascati electron-positron collider, based on the Crab-Waist collision scheme, has successfully completed the preliminary phase with the SIDDHARTA-2 detector aimed at testing and optimizing the performances of the machine and the experimental apparatus.
In this configuration the collider has delivered to the experiment, using gaseous 4He targets, a data sample suitable to perform studies about the kaonic helium transitions with an accuracy which is the status of the art in the field.
As a next step DAFNE is planning a new run finalized to deliver data to the detector in order to study the more elusive kaonic deuterium transition.
In this context the setup and the performances of collider the are presented with special attention to the strategy adopted to reduce the background shower on the experimental apparatus.
We discuss the beam requirements for indirect searches of dark matter and feebly coupled particles using advanced accelerator concepts. A parameter comparison reveals dielectric laser acceleration (DLA) as a promising candidate for delivering the needed single-electron beams in the 5-100 GeV energy range or beyond. We suggest a parameter set for a baseline DLA-based dark sector accelerator. Enhancements through combining dielectric laser deflectors with a segmented detector or by making the dielectric structure be part of the laser oscillator might offer a performance well exceeding the “Extended LDMX” proposal based on LCLS-II.
After the discovery of the Higgs boson at the LHC, particle physics community is exploring and proposing next accelerators, to address the remaining open questions on the underlying mechanisms and constituents of the present universe. One of the studied possibilities is FCC (Future Circular Collider), a 100-km-long collider at CERN. The feasibility study of this future proposed accelerator implies the definition of tolerances on magnets imperfections and of the strategies of correction in order to guarantee the target performances of the High Energy Booster ring. The efficiency of the correction scheme, used to control the orbit, directly bounds the corrector needs and magnet tolerances. Analytic formulae give a first estimation of the average rms value of the required linear correctors’ strengths and of the allowed magnets misalignments and field quality along the entire ring. The distribution of the correctors along the ring is simulated using the cpymad code, in order to verify the quality of the residual orbit after the proposed correction strategy and compared with the analytical predictions. First specifications of the orbit correctors strength and tolerances for the alignment of the main elements of the ring are presented. The limits of the studied correction scheme and method are also discussed.
Nb3Sn, NbTiN and NbN are superconductors with a critical temperatures of 18.3, 12.6-17, 11.6-17.5 K, respectively, that are higher than that of Nb (9.3 K). Hence, at 4 K they have an RF resistance of an order of magni-tude lower than that of Nb, which leads to quality factors above those of Nb. In recent years, there has been an extensive effort converting Nb cavities into Nb3Sn by alloying the top inner layer of the cavity using Sn diffusion at a high temperature with some degree of success, however, the reproducibility remains a major hindering and limiting factor.
In this study, we report on PVD deposition of NbTiN and NbN inside 6 GHz cavity in an external magnetic coil configu-ration. The deposition is done at elevated temperature of about 650 C using Nb53Ti47 target and Nb rod.
We report on the superconducting properties, film structure and its stoichiometry and surface chemical state. The films have been characterised with SEM, XRD, XPS, EDS, SIMS, SQUID magnetometer and direct RF measurement of the cavity.
The Spallation Neutron Source (SNS) employs six cavities in the Drift Tube Linac (DTL) section to accelerate the H- ion beam to 87MeV. Each cavity is energized by a 2.5MW peak power klystron at 402.5MHz using rapid tapered waveguide iris couplers. All six original iris couplers have been in operation without replacement for over two decades. The increased RF power demands of the Proton Power Upgrade (PPU) project and operational problems, including arcing, temperature excursions, and vacuum bursts, have prompted the development of new iris coupler spares. The original iris couplers were made of GlidCop material, which is known to be mechanically strong and thermally stable, but is porous, expensive, and difficult to use in fabrication. To overcome these problems, the new spare couplers use Oxygen-Free Copper (OFC) and stainless steel (SS). This paper will discuss the mechanical, thermal and RF design, as well as challenges in the final coupler fabrication.
The Future Circular electron-positron Collider (FCC-ee) is planned to operate with beam energies from 45.6 to 182.5 GeV and beam currents from 5 to 1400 mA. This will enable precision physics at the four operational points, Z, W and Higgs boson and the top and anti-top quarks. This work will focus on the RF structure design for the ttbar operation point to reach a beam energy and current of 182.5 GeV and 5 mA, respectively. A 5-cell elliptical SRF cavity operating at 801.58 MHz is designed and optimized with a strong focus on minimizing higher-order modes impedances.
In the Electron Ion Collider (EIC), to be built at Brookhaven National Lab, the beams collide with a crossing angle of 25 mrad and an aspect ratio of 12 to 1. The orbit control in the interaction region is critical to achieve and to maintain the design luminosity and polarization, and to control synchrotron radiation induced detector background. In his report, the authors will introduce the IR orbit control system, including a slow orbit feedback and a fast local IR orbit feedback, and the associated simulation studies.
High brightness beams are desired for application to Inverse Compton Scattering (ICS) systems for generation of high-quality x- and γ-rays. It opens new opportunities for nuclear physics research in fields such as nuclear photonics, nuclear astrophysics, photo-fission, production of exotic nuclei, applications in medicine, industry and space science. In ICS mechanism high energy electron is interacting with photon. It results in scattered photon with high energy.
Results from computer simulations are presented. Different configurations of S-band injector were analysed. Photocathode RF electron source with diverse arrangement of magnetic devices for beam confinement, and standing wave cavity for initial particle acceleration were implemented. Electron beam parameters have been investigated with use of computer program for tracking particle beam through defined external electric and magnetic fields. Because cross-section of collision between electron and photon beam is very low, high brightness electron beam is crucial specification for gamma beam systems. Electron beam parameters of interest are emittance, beam spot size, average energy, energy spread, electron bunch length, Twiss parameters. Beam density, number of particles in bunch must find good compromise between optimum necessary for creation of high-performance gamma rays and limit in available technology.
LEAF (Low Energy heavy ion Accelerator Facility) is a low-energy high-intensity heavy-ion LINAC complex for multidiscipline research. At present, the beam repetition rate is the same as the LINAC frequency of 81.25 MHz. A lower frequency would be desirable for many types of experiments employing time of flight data acquisitions. A method of increasing the bunch spacing to 98 ns by combining a 10.156 MHz pre-buncher before the RFQ and an RF chopper after the RFQ has been proposed. This paper reports the design studies of such a low-frequency pre-buncher. A resonator-based buncher is the best choice since lumped circuit-based buncher cannot provide the high voltage we expect for the efficient bunching of ion beams with an A/q of 7. According to the simulation result, the bunching efficiency of a 3-harmonic buncher will merely increase by 1% compared to a 2-harmonic buncher. We decide to design a two-harmonic buncher based on the little improvement in bunching efficiency. We optimize the length of electrodes so that the utilization of the parasitic field is maximized. The beam dynamics analysis indicates that the voltage amplitude and the RF power can be lowered by 1.3 times and 2.2 times by optimizing the electrode length.
We propose to develop a compact superconducting cyclotron to accelerate H2+ ions for isotope production since using H2+ allows the use of a stripper foil after extraction from the cyclotron to remove the binding electron, thereby doubling the electrical beam current. An RFQ, partially embedded in the cyclotron yoke, will be used to bunch and axially inject the H2+ beam into the cyclotron’s central region because RFQ has excellent bunching capability. In this paper we are presenting the design of the RFQ, including beam dynamics, electromagnetic structure and geometrical cavity.
Hybrid multi-bend-achromat (HMBA) concept, proposed to develop low emittance lattices with large dynamic aperture, has been adopted in some diffraction-limited storage ring (DLSR) designs. In this paper, we show a lattice with hybrid 7BA bending arcs for the super tau charm facility (STCF) in China, which is an electron-positron circular collider. Two kinds of phase advances between dispersion bumps of two neighboring 7BAs have been studied at the optimized energy of 2.0 GeV with luminosity more than $5 \times 10^{34} cm^{-1}s^{-1}.$
A S band high power klystron for BEPCII operating at frequency of 2856 MHz has been designed and simulated at Institute of High Energy Physics, Chinese Academy of Sciences. A thermionic electron gun have been designed. A beam current of 379 A is obtained at operating voltage of 325 kV with cathode current density of 6.6 A/cm2. Then, the full 3-dimensional particle-in-cell simulation of the whole klystron in CST verified that the klystron efficiency was achieved about 40% with output power of 50 MW. In additon, the RF design of cavities for interaction region is described. So far, the mechanical design of this klystron has been completed and the fabrication is in progress.
Presented in this paper is the beam optics design of the final focus system (FFS) for the Super tau charm facility (STCF) in China, which is an electron positron circular collider with center-mass-energy (CME) from 2 GeV to 7 GeV. To achieve a luminosity of more than $ 5 \times 10^{34} cm^{-1}s^{-1}$, FFS with Large Piwinsky angle and crab waist scheme.
A Boron Neutron Capture Therapy facility requires a high flux of neutrons (approx. 10^9 thermal or epithermal n/s*cm^2) with low contamination content (gamma and off energy neutrons). The core of such a facility is a low energy high intensity proton linac, coupled with a high power beryllium neutron production target, followed by a proper Beam Shaping System. In this paper we shall discuss various aspects of the optimization of this system, on the bases of the R&D results available in view of the construction of a high performance BNCT facility in Italy.
A dual energy electron storage ring cooler was proposed to maintain a good hadron beam quality against intra-beam scattering and all heating sources in a collider. This configuration has two energy loops. Electron beam in the low energy loop extracts heat away from the hadron beam through Coulomb interaction, while electron beam in the high energy loop loses heat through its intrinsic synchrotron radiation damping. Early studies of this concept show promising results and demonstrate its validity. This paper presented further optimization of optics design and parameters, and evaluation of improved cooling performance.
Based on the key scientific questions in the frontier of particle physics field, the current status and future development trend globally and domestically of accelerator-based particle physics experiments, a Super Tau-Charm Facility (STCF) is proposed by taking into account the advantages in the relevant fields in China. The STCF is a new-generation electron-positron collider facility that has a center-of-mass energy of covering 2 to 7 GeV and a peak luminosity of 5×10^34cm^-2s^-1 at a center-of-mass energy of 4 GeV. It consists of an accelerator, including double storage rings of circumference approximately 800 meters and a linear injector of length approximately 400 meters, and a particle spectrometer. This paper discussed the key issues of accelerator physics and technologies. Also, the accelerator research progress of the projects are presented.
The FFA@CEBAF energy upgrade study aims to approximately double the final energy of the electron beam at the Continuous Electron Beam Accelerator Facility (CEBAF). It will do this by replacing the highest-energy recirculating arcs with fixed-field alternating gradient (FFA) arcs, allowing for several more passes to circulate through the machine. This upgrade necessitates the re-design of the vertical spreader sections, which separates each pass into different recirculation arcs. Additionally, the FFA arcs will need horizontal splitter lines to correct for time of flight and R56. This work will present the current state of the spreader re-design and splitter design.
The muon-dedicated linear accelerator is being developed for the muon g-2/EDM experiment at J-PARC. To suppress the decay loss during acceleration, the alternative phase focusing (APF) method inter-digital H-mode drift tube linac (IH-DTL) is adopted in the low-velocity region following a radio-frequency quadrupole linac (RFQ). We are planning to accelerate muons in 2024 using the RFQ and the IH-DTL which will accelerate muons from 8% to 30% of the speed of light with an operating frequency of 324 MHz. After the IH-DTL, a diagnostic beamline will be placed to measure the beam energy and quality after acceleration, and its design, which consists of magnets and bunchers, is underway. In this poster, we will report on the development status of the diagnostic beamline.
The J-PARC muon g-2/EDM experiment aims to measure the muon anomalous magnetic moment and search the electric dipole moment, which sensitive to new physics with high precision. This experiment uses a novel method using the low-emittance muon beam achieved by cooling and re-acceleration. We are integrating the developments of the upstream of the beamline, and aim to achieve RF acceleration of ultra-slow muon in 2023.
There is a issue in controlling the beam orbit at the injection into the accelerator. The ambient magnetic field around beamline causes the beam orbit shift. It reduces the efficiency of the injection into the accelerator and also causes serious emittance growth. So, we evaluated the orbit of the beam emitted from the ultra-slow muon source by simulation. In oredr to correct beam orbit, we have also developed a low energy beam transport line including compact electrostatic deflector which satisfies the spatial limitations of the beam area.
In this paper, the development of the low energy beam transport line for RF acceleration of ultra-slow muon is reported.
In this presentation, we will introduce development plan and current status of structure based wakefield accelerator. Lithography scheme is being considered to fabricate accurate structure and will be performed in PLS-II 9D beamline.
The EIC electron storage ring (ESR) has very tight tolerances for the amplitude of electron beam position and size oscillations at the interaction point. The oscillations at the proton betatron frequency and its harmonics are the most dangerous because they could lead to unacceptable proton emittance growth from the oscillating beam-beam kick from the electrons. To estimate the amplitude of these oscillations coming from the magnet power supply current ripple we need to accurately account for the eddy current shielding by the vacuum chamber. The dipole and multipole chambers in the ESR have elliptical cross-section with 4-mm thick copper wall. At the frequencies of interest, the skin depth is a small fraction of the wall thickness, so the commonly used single-pole expressions for eddy current shielding transfer function do not apply. In this paper we present new (to the best of our knowledge) analytical formulas that adequately describe the shielding for this frequency range and chamber geometry and discuss the implications for the power supply ripple specifications at high frequency.
The stability of beams is a crucial parameter for efficient and reliable machine operation, especially in the case of a lepton collider such as the Future Circular Collider (FCC-ee). The orbit can be perturbed either by machine inherent or environmental sources, e.g. ground motion and cultural noise, whose effects can be propagated through the whole ring. The frequencies of these effects typically range from very low to extremely high frequencies (up to 3 kHz). The study we are currently performing is aimed at evaluating the impact of ground motion induced shifts of all quadrupoles placed along the ring, thus to evaluate global spatial coherence. To carry out this study, a plane uniform wave which moves the quadrupoles vertically, is simulated. The MAD-X program performs the computation and the vertical closed orbit offset at the four Interaction Points is extracted. The amplification factor is defined as the ratio of the vertical orbit offset with the amplitude of the ground motion wave at the considered location. A Python script evaluates this factor, and plots it, relative to the frequency of the plane ground wave. A status of this work is given.
The Electron Ion Collider is adopting a crabbing scheme of 25 mrad crossing angle. The local crab cavity system designed to kick the bunches in the first IR also introduces higher order multipoles components in the electric field which affect the dynamic aperture. We have studied the strength of each multipole up to n = 5, or decapole, with respect to the main dipole field in different operating scenarios. Dynamic aperture study has continued with the new lattice design of EIC, and also a comparison of multipole effect for different phase advance between the two crab cavity sets across the IP is shown in this paper. The method of decreasing the sextupole component is investigated due to the dynamic aperture requirement.
An electromagnetic chopper is an important component of particle accelerators. It helps to provide users with different time structure beams. It is usually placed in the low energy beam sections of accelerators. In general, the chopper has rise and fall times of the order of a few nanoseconds. Due to this rise and fall time, post-chopper beam dynamics are affected. As part of this master thesis, the dependence of the beam parameter on the WNR chopper model (rise time, fall time, flat peak time) will be explored and CST software will be used for beam dynamics simulations.
A scheme for electron acceleration by self focused -Gaussian laser pulses in under dense plasma has been presented. The relativistic increase in the mass of plasma electrons gives nonlinear response of plasma to the incident laser pulse resulting in its self focusing. Under the combined effects of saturation nature of relativistic nonlinearity of plasma, self focusing and diffraction broadening of the laser pulse, the beam width of the laser pulse evolves in an oscillatory manner. An electron initially on pulse axis and at the front of the self focused pulse, gains energy from it until the peak of the pulse reaches. When the electron reaches at the tail of the pulse, the pulse begins to diverge. Thus, the deacceleration of the electron from the trailing part of pulse is less compared to the acceleration provided by the ascending part of the pulse. Hence, the electron leaves the pulse with net energy gain. The differential equations for the motion of electron have been solved numerically by incorporating the effect of self focusing of the laser pulse.
In VECC, Radioactive Ion Beam (RIB) facility has been built to create ion beams of radioactive isotopes using electron LINAC. An integrated supervisory control system for remote operation of electron gun and Low Energy Beam Transport (LEBT) line of the e-LINAC has been developed at VECC. The system consists of a Filament Power Supply (PS), Grid PS, Cathode Biasing High Voltage PS, RF Signal Generator, Camera Trigger Unit, Steering magnets PS, Solenoid PS, Vacuum Gauges, Faraday cups, and current integrator. EPICS is chosen for developing the control system because of its distributed network-based architecture. The field devices of the e-LINAC are connected with the control system with either analog/digital hardware interface or serial protocols (like RS232/RS485/Ethernet) based communication interface. A modular network-based Programmable Automation Controller (PAC) is selected for interfacing field devices with analog/digital hardware interface. An embedded EPICS Input Output Controller (IOC) was ported on the embedded PAC platform. The communication protocol based field devices are directly interfaced from EPICS IOC running on a server PC using asynDriver. An integrated GUI has been developed for the operator's interfacing using Control System Studio (CSS). Various safety interlock features have also been incorporated into the system at the hardware and software levels. The control system architecture and details of developing EPICS IOC and OPI are discussed in this paper.
Circular Electron-Positron Collider (CEPC) is a 100 km circumference double-ring Collider, the high luminosity lattice in CEPC TDR is half lower emittance compared with the lattice in CEPC CDR. The dynamic aperture is strongly sensitive to the magnet misalignments and field errors. We present the study of the error correction for the CEPC TDR lattice and the dynamic aperture tracking after correction. The scheme of the correction and the resulting performance are discussed.
The Future Circular electron-positron Collider (FCC-ee) is a proposed next generation collider with plans to reach unprecedented luminosity for study of Higgs physics, as well as unprecedented energies for lepton colliders in the 91 km machine. To maximize the integrated luminosity it is critical that FCC-ee utilize full-energy top-up injection to maintain the current of the colliding beams. Two approaches to top-up injection are deemed viable for FCC-ee, Multipole Kicker Injection and Conventional Orbit Bump Injection, and both on- and off- momentum schemes are considered for each as well. We study these injection approaches in the presence of various element misalignments and machine optics errors around the machine and specifically within the injection straight to evaluate their strengths and weaknesses to optimize top-up and collision performance.
The Interaction Regions (IR) of many colliders benefit from the application of leading-edge technologies to ensure the highest possible luminosity delivered to the experiments. Leading-edge low-beta focusing magnets and crab cavities to handle individual bunches are critically important to increase the instantaneous and integrated luminosity in future Colliders.
The High-Luminosity LHC Upgrade, HL-LHC, with Nb3Sn Magnets (called MQXF) and Superconducting Radio Frequency (SRF) crab cavities (of two types, called DQW and RFD) is a world-wide collaborative project under construction in this decade to utilize the solutions mentioned above as key ingredients to increase tenfold the integrated luminosity delivered to the CMS and ATLAS experiments in the next decade. The HL-LHC AUP is the US effort to contribute approximately 50% of the low-beta focusing magnets and crab cavities for the HL-LHC.
In this contribution we present the valuable lessons learned by the US efforts in the procurement, construction, and testing phases of the Nb3Sn focusing magnets and SRF crab cavities. We will report on the experience gathered by HL-LHC AUP in the production of the first half of deliverables (magnets MQXFA03 to MQXFA13). We will also report on the test of the first cryoassemblies and the status of the cavities’ development, production and testing.
Both the technical and project management lessons-learned will inform applications of these technologies to future colliders and projects.
A method of decreasing the required footprint of linear electron accelerators and to improve their energy efficiency is utilizing short RF pulses (~9 ns) with Dielectric Disk Accelerators (DDA). A DDA is an accelerating structure that utilizes dielectric disks in its design to improve the shunt impedance. Two clamped DDA structures have been designed and tested at the Argonne Wakefield Accelerator. The single cell clamped DDA structure achieved an accelerating gradient of 102 MV/m with no visible damage in the rf volume region. Based on the success of that experiment, a multicell clamped DDA structure has been designed and tested at high power. Simulation results for this new structure show a 108 MV/m accelerating gradient with 400 MW of input power with a high shunt impedance and group velocity. Engineering designs were improved from the single cell structure to ensure consistent clamping over the entire structure. The results of the high power test will be presented.
The protection of the tertiary collimators (TCT) and the aperture in the LHCs’ triplet magnets in case of an asynchronous beam dump requires sufficient retraction between the TCTs and the beam dump absorbers. A method has been developed to measure the retraction using circulating beams. It uses a long orbit bump to reproduce the trajectory change that the extraction kickers' asynchronous firing would cause. This paper reports on the experimental validation of the method performed at 6.8 TeV beam energy, using the nominal proton physics optics and purposedly detuned optics configurations. It is shown that the method has sufficient sensitivity to correctly quantify the retraction margin reduction in the non-nominal optics. The potential benefits and operational uses of the method for machine protection validation are discussed.
The FCC-ee project takes a step forward towards the discovery of new physical phenomena beyond the frontier of the standard model, by aiming at unprecedented center of mass energies and luminosities in a double-ring lepton collider. In order to explore potential improvements to the current lattice design, this paper looks at the use of combined function magnets within the short straight sections of the arc cells. The use of High Temperature Superconductors (HTS) with an operating temperature of 12 K and maximum field of 18.2 T for the combined function magnets allows increasing the bending radius and decreasing the synchrotron radiation. A first design is presented with comparisons to the current baseline.
During 2022, a dedicated study was undertaken at CERN, together with FCC Feasibility Study collaborators, aimed at proposing a robust configuration for the FCC-ee arc half cell. The proposed configuration takes into account integration aspects of the elements in the arc cross section, both for the booster and the collider, as well as aspects related to powering, cooling and ventilation, supporting and alignment, optics, instrumentation, handling and installation. The interfaces between the arc elements and the straight sections have also been analyzed. This paper summarizes the main conclusions of the assessment, and reports the preliminary engineering analyses performed to design the supporting system of the booster and of the collider. A proposal for a possible mock-up of the arc half-cell, to be built at CERN in the next years, is also presented.
The Future Circular electron-positron Collider, FCC-ee, is designed for unprecedented precision for particle physics experiments from the Z-pole up to above the top-pair-threshold, corresponding to a beam energy range from 45.6 to 182.5 GeV. Performing collisions at various particle physics resonances requires precise knowledge of the centre-of-mass energy (ECM) and collision boosts at all four interaction points. Measurement of the ECM by resonant depolarization of transversely polarized pilot bunches in combination with a 3D polarimeter, aims to achieve a systematic uncertainty of 4 and 100 keV for the Z-pole and W-pair-threshold energies respectively. The ECM itself depends on the RF-location, beamstrahlung, longitudinal impedance, the Earth tides, opposite sign dispersion and possible collision offsets. Monochromatization schemes are envisaged to be applied at certain beam energies to reduce the energy spread. The latest results of the energy calibration, polarization and monochromatization studies are reported here.
The Large Hadron Collider (LHC) at the European Organization for Nuclear Research (CERN) is the world's largest and most powerful particle accelerator colliding beams of protons and lead ions at energies up to 7 ZTeV. ALICE is one of the detector experiments optimised for heavy-ion collisions. A fixed-target experiment in ALICE is considered to collide a portion of the beam halo, split using a bent crystal, with an internal target placed a few meters upstream of the detector. For proton beams, we have already demonstrated that such a setup provides satisfactory performance in terms of particle flux on target and that it can be safely operated in parallel to regular beam-beam collisions. On the other hand, in the case of lead ion beams a beam halo is populated with nuclei of many species that may differ in terms of charge, mass and magnetic rigidity, which makes such a scenario more challenging to operate. In this paper, we summarize our first considerations of the feasibility of a fixed-target layout at ALICE to be operated with lead ion beams in the LHC.
The design of a muon collider complex requires to overcome challenges associated with muons short lifetime. To reach the expected luminosity for a multi TeV muon collider ring an interaction region with beta values of the order of a few millimetres is required. Resulting challenges are the development of a chromatic compensation section that is not degrading the physical and dynamical aperture, while allowing the control of the momentum compaction factor, as well as the control of the radiation due to muons reaching the earth surface. A preliminary version of a 10 TeV centre-of-mass energy muon collider ring fulfilling these requirements and taking limitations from the detector and magnet design into account is presented.
At LNL (Laboratori Nazionali di Legnaro), the vacuum system of ALPI (Acceleratore Lineare Per Ioni) accelerator includes about 40 pumping groups installed in the 90s. Obsolescence and rigidity of the used hardware and deficit of spare parts required a complete renovation of the system and relative controls. In 2022 we made the first steps of the system renovation with the development and installation of the new high level control system part based on EPICS (Experimental Physics and Industrial Control System) and CSS (Control System Studio). Meanwhile, we designed a new flexible and configurable low level control system part running on a Siemens PLC and exploiting MOXA serial server to control the renewed pump groups and pressure gauges. Moreover we extended the EPICS control system to support both HW configurations, providing to users the same information and graphic interface. The plan for the next years is to replace the legacy hardware with new racks running the new control system, provide service continuity, retrieve spare hardware, debug the PLC software and extend the EPICS control system with new features. This paper describes the adopted strategy and the upgrade status.
Chromaticity up to the third order in the LHC has been well observed in the LHC’s first and second operational runs, with regular beam-based measurements performed during commissioning and machine development. In previous runs however, no higher-order chromaticity could be observed. In 2022, dedicated collimators setups meant optics measurements could benefit from an improved range of momentum-offset for the chromaticity studies. This allowed the observation of fourth and fifth order chromaticity in the LHC at 450GeV for the first time. Measurements were performed for several machine configurations. In this paper, results of the higher order non-linear chromaticity are presented and compared to predictions of the LHC magnetic model.
A two-day test of operation with Pb ion beams was carried out in the CERN Large Hadron Collider (LHC) in 2022, with the aim of gaining experience in view of the future high luminosity heavy-ion physics runs from 2023 onwards. The LHC experiments received the first Pb-Pb collisions at a record energy of 5.36 TeV centre-of-mass energy per colliding nucleon pair (beam energy 6.8 Z TeV). Bunch trains created with a new production scheme in the injectors, including slip-stacking, were injected into the LHC, with the collimation of nuclear beams with bent crystals tested along with a new collimation scheme for collision products. This paper describes the conditions and outcomes of these tests, which are critical steps in the upgrade to higher luminosity.
The proposed FCC-ee machine is a high-energy, high-intensity and high-precision lepton collider which will require to reduce as much as possible the differential motions of its two beams at the interaction points. In this prospect, the vibration impacts of the quadrupoles in the region close to the interaction point are investigated. Considering the z-pole optics design and its dedicated optics simulation under MAD-X, the present paper describes the integration of the dynamics aspects (vibrations mitigation) to render the modelling more realistic towards operation. This simulation is based on the "particle tracking" mode. In this prospect, dynamic characteristics of the designed mechanical assembly are estimated according to an analysis in finite element models. Required transfer functions and realistic temporal sequences along the assembly are thus created and they can be implemented as inputs to the optical simulations to verify that this assembly allows the expected beam parameters. The obtained results on a dedicated cantilever mock-up are presented and the last optics simulations are discussed.
GaAs cathode is a unique device generating a spin-polarized electron beam by photo-electron effect with a circularly polarized laser illumination. Negative Electron Affinity (NEA) surface which is artificially made has an essential role in spin polarization, but the NEA surface has limited vitality. In this study, we activated GaAs as NEA cathode by evaporating Cs, K, and Sb metal on its cleaned surface. The experimental results including the quantum efficiency spectrum and the lifetime will be presented.
One of the design requirements to reach a high luminosity in the Electron Ion Collider (EIC) is the collision of matched spot sizes of hadron and electron beams at the IP, with a horizontal to vertical emittance ratio of up to almost 20. However, the natural vertical emittance of electron beams in the Electron Storage Ring (ESR) in EIC is a few orders of magnitude smaller than the horizontal one. Increasing the vertical beta function at the IP to reach the necessary vertical beam size may not be acceptable due to the associated growth of the beam-beam tune shift. We explore an approach to generate the vertical emittance through the transverse coupling using skew quadrupoles in one of ESR arcs, while keeping the rest of the ESR decoupled. In this paper, we present the study results on the modification of ESR optics, evaluation of the dependence of electron polarization on the excited vertical emittance and minimization of the depolarization through the spin match mechanism.
Studies of the beam spectrum of the Large Hadron Collider (LHC) have revealed the existence of harmonics of the mains frequency (50~Hz), ranging from 50~Hz to 8~kHz, in the form of transverse dipolar excitations. The restart of the LHC operation in Run 3 was accompanied by substantial improvements in the beam instrumentation. In particular, the upgrade of the transverse damper’s observation system (ADTObsBox), currently providing bunch-by-bunch and continuous position measurements, allows for the first time a systematic follow-up of the harmonics’ evolution during the run. In this paper, we present parasitic observations collected during the LHC physics operation, as well as results from dedicated experiments with the aim of providing further insights into the source of the perturbation, especially concerning the 50~Hz harmonics around 8~kHz. These tests include modifications in the operation mode of systems such as some of the Uninterruptible Power Supplies, while observing potential changes in the spectrum of the beam position data.
Travelling wave (TW) SRF accelerating structures offer several advantages over the traditional standing wave structures: substantially lower Hpk/Eacc and lower Epk/Eacc, ratios of peak magnetic field and peak electric field to the accelerating gradient, respectively, together with substantially higher R/Q. In this paper we discuss how a linear collider Higgs factory HELEN can be built using TW-based SRF linacs. We cover a plan to address technological challenges and describe potential ways to upgrade the collider luminosity and energy.
Run 4 will be the first operational run of the LHC with full deployment of the upgrades from the High Luminosity (HL-LHC) project planned for 2026-2028 (Long Shutdown 3). The commissioning goals for the first run were defined to approach steadily the design beam current, while already fulfilling significant luminosity goals. Despite extensive operational experience already gained, intensity limitations due to electron cloud and/or impedance might require to further reduce beta* values from the very early stages. The paper presents various optics configurations considered under different Run4 scenarios together with their expected dynamic aperture.
The Spallation Neutron Source (SNS) recently took delivery of a third Radiofrequency Quadrupole (RFQ03) that will ultimately be installed on the front-end (FE) of the SNS Linac. The first RFQ (RFQ01) operated in the SNS FE for more than a decade before being replaced with the second RFQ (RFQ02). RFQ01 was relocated to the Beam Test Facility (BTF) where it operated for five more years. The RFQ02 was initially installed in the BTF for high power testing and used with H- beam for BTF operation. It replaced RFQ01 in the SNS FE in 2017 and has been operating for beam production since then. There are some differences between the three RFQs. RFQ01 has a square cross-section with pi-mode stabilizing loops (PISLs) with the structure being fabricated using two layers of materials, GlidCop outside and OFHC inside. RFQ02 and RFQ03 has an octagonal cross-section with end-wall stabilizer rods and was fabricated using OFHC only. RFQ01 suffered some field flatness distortion incidents that resulted in degradation in beam transmission efficiency and required RF tuning. RFQ02 has performed well but had a melted RF seal in the high energy end wall, that was ultimately mitigated by a redesign of the end flange seals. The SNS decided to order RFQ03 that has a design that followed that of RFQ02 closely, but end-wall contacts were modified to prevent RF seal failure. This report presents the testing, installation, high power RF operation, and design improvements of the RFQ03.
FCC-ee performance is challenged by magnetic errors and imperfections. Magnetic design simulations predict a systematic quadrupolar component in the arc dipoles significantly impacting the machine optics. This paper studies the impact of this component in the beta-beating and explores potential mitigations.
In this paper we present the first results of full 6D multi-bunch tracking through the new Drive-Beam decelerator lattice for the first stage of the Compact Linear Collider (CLIC). Using the new PLACET3 tracking package, we evaluate the impact of both static and dynamic variations in bunch length, shape, timing and energy profile on the decelerator extracted power.
The Future Circular Electron-Positron Collider (FCC-ee) aims to achieve unprecedented energies and luminosities. This can only be achieved using complex insertion region optics that set high challenges for commissioning and operating the machine. In the following we discuss some of the optics correction methods anticipated to be used to achieve the targets of the FCC-ee.
The team at LANL continues efforts for the LANSCE Accelerator Modernization. This paper summarizes the progress in developing of the proposed concept of the modernization, and the major technical challenges that are expected in this concept. Separate subsystems are designed on the conceptual level, and the computer models for beam dynamics simulations are established and presented here. The technical details of the proposed subsystems are presented in the conceptual form, and the limited analysis of alternatives is performed and described.
The electron-ion collider will utilize a major portion of the existing RHIC rings for its hadron storage ring (HSR). This paper describes the lattice design of the HSR. Presently, RHIC consists of two rings, each of which contains 6 straight sections, and between those straights are arcs, each consisting of 11 FODO cells. The HSR uses 7 of the existing RHIC arcs which are unmodified, other than powering changes to allow the beam to travel opposite to its direction in RHIC in selected arcs. We select the arc in one sextant to keep the orbit period of the HSR the same as that of the new electron storage ring, depending on whether we are operating at hadron energies around 41 GeV/u or in the range of 100 GeV/u to 275 GeV/u. We describe the purpose and lattice design of the 6 straight sections of the HSR. We briefly describe several operations that we will compute the HSR, including setting the tune and chromaticity, radial shift for period control in the high energy regime, injection and ramp, RF manipulations, and gamma transition jump.
We present the lattice design for the interaction region (IR) for the Electron-Ion Collider. We specify the requirements that the IR must meet, both for the hadron and electron beams themselves and for the collision products and radiation that must be transmitted through the magnet apertures. We align the hadron magnets downstream of the detector to pass the collision products while minimizing stray fields in the electron line. We set the fields and gradients in the magnets near the IR to meet the required specifications at both the interaction point and the crab cavities. We describe how these magnet placements can be implemented in accelerator design codes. We match the hadron IR to the existing RHIC arcs, and describe the consequences for the spin manipulation snake and rotators. We consider the consequences of replacing the two defocusing quadrupoles on the downstream side of the hadron IR with a single tapered quadrupole, and show how that quadrupole can be effectively modeled in standard accelerator design codes.
The Electron Ion Collider (EIC) Hadron Storage Ring (HSR) will utilize the Relativistic Heavy Ion Collider (RHIC) arcs and modified straight sections. Due to these modifications in the straight section of the on project electron Proton Ion Collider (ePIC) experiment, a new injection system needed to be built one arc downstream of the existing RHIC injection system. The new injection system will have capability of injecting 290 bunches with a maximum rigidity of ~81 Tm. In addition to the new injection system, the hydrogen jet (HJET) and proton-carbon (pC) polarimeters will be located in the straight section downstream of injection. This paper will report the modifications required to the lattice, optics, and magnets.
The first year of Run 3 of the Large Hadron Collider (LHC) revealed significant changes in both linear and nonlinear optics errors with respect to Run 2. Several iterations of optics corrections were required to successfully bring the linear optics within operational tolerances. This paper presents the current status of optics corrections in the LHC and the challenges experienced in commissioning the optics to a beta* of 30cm in a single commissioning year after the Long Shutdown.
Local coupling correction in Interaction Regions (IRs) and global coupling correction based on Base-Band Tune (BBQ) measurement have been performed routinely for RHIC operation. However, one still observes significant residual local coupling measured by beam position data. For the Electron-Ion Collider (EIC) project, betatron decoupling for the hadron beam needs to be improved to maintain a large horizontal to vertical beam emittance ratio (12:1). In this paper, we will analyze the cause for noticeable residual coupling in RHIC and propose an integrated local and global betatron coupling correction based on beam position measurements and verify the new scheme with simulation and measurements.
To provide a more accurate and stable Radio-Frequency (RF) signal in conditioning and processing test progress, it is necessary to design an Low-Level Radio-Frequency (LLRF) control system which can provide high precision RF driving signal based on meeting the amplitude and phase stabilization requirement. Through Feed-Forward operation, accurate phase adjustment and amplitude adjustment are realized inside the pulse, to realize the precision and automation of phase-inversion, amplitude stabilization, phase stabilization, and waveform adaptation matching. An LLRF System integrated with feed-forward control and vector modulation output was designed and built, the long term working stability of the LLRF system was verified during a new 50MW S band Klystron conditioning progress.
A muon linac is under development for the muon g-2/EDM experiment at J-PARC. The muons are once cooled to room temperature and then re-accelerated up to 212 MeV by four accelerating structures to realize a low-emittance muon beam. As for the low-beta section, we have developed an interdigital H-mode drift tube linac (IH-DTL), implementing the alternating phase focusing (APF) scheme. The IH-DTL accelerates muons from β = v/c= 0.08 to 0.28 at an operating frequency of 324 MHz. In this paper, the design, fabrication, and low-power test of the APF IH-DTL are reported.
The Advanced Sources and Detectors project is building an advanced multi-pulse linear induction accelerator capable of generating a 1.4 kA electron beam at energies up to 24 MeV. The accelerator, named Scorpius after the brightest known x-ray source in the sky, will be unique in its use of solid-state pulsed power (SSPP) to generate the voltage pulse for the injector and accelerating gaps throughout the accelerator, giving Scorpius unique control of the pulse shape by independently triggering 45 individual stages stacked in each of nearly 1,000 line replaceable units (LRUs). To take full advantage of the SSPP flexibility, automated optimization of the pulse shape to a desired waveform is currently under development. To demonstrate this capability, nonlinear surrogate circuit models of the SSPP have been developed using the hybrid transmission line/modified nodal analysis code, CASTLE, that include parasitics and a dummy load to generate reflections. Data-efficient Bayesian optimizations calling CASTLE directly for each iteration are compared with results from a convolutional neural network or other machine learning model trained on data generated by CASTLE, and the effect of the number of stages on pulse flattening is discussed.
We’ll introduce a high precision active motion controller based on machine learning (ML) technology and electric piezo actuator. The controller will be used for srf cavity active resonance control, where a data-driven model for system motion dynamics will be developed first, and a model predictive controller (MPC) will be built accordingly. Simulation results as well as initial test results with real SRF cavity will be presented in the paper.
In 2022, the Large Hadron Collider started its third operational run. Following the end of Long Shutdown 2 (2019-2021), a careful re-commissioning of the machine protection system (MPS) took place. The initial hardware and beam commissioning period was followed by a six-week-long intensity ramp-up, during which the number of circulating bunches was successively increased up to 2460 bunches per beam. After each pre-defined intensity step, a detailed analysis of the functionality of the MPS was performed, before advancing to the next step. It paved the way to reach a record stored energy of almost 400 MJ per beam in 2022. This was achieved without observing any beam-induced damage, confirming the excellent performance of the MPS.
The paper reviews the strategy for the re-commissioning and intensity ramp-up from a machine-protection perspective. It highlights issues encountered and provides examples of specific validations performed for new operational and experimental devices. It then examines the challenges arising from the required frequent reconfiguration of the accelerator for special physics runs and machine development studies, and discusses the lessons learnt.
The CLIC Beam Delivery System (BDS) transports the lepton beams from the exit of the Main Linac to the Interaction Point (IP). The Final Focus System (FFS) is the last part of the BDS and its role is to focus the beam to the required size at the IP and to cancel the chromaticity of the Final Doublet (FD). MAD-X and MAD-NG are simulation codes for beam dynamics and optics that are used for particle accelerator design and optimization. This paper presents a comparison between the two codes to achieve the best performance of the design of the FFS, including the optimization methods, the speed performance and the physics accuracy.
The project of PolFEL free electron laser comprises 185 MeV cw-linac furnished with ASG electron gun and 4 Rossendorf-like cryomodules. Magnetic lattice has been designed applying alike air cooled quadrupole magnets. FODO quadrupoles in undulator section differ with trimmed coils. A variety of dipoles has been designed: 14 – degrees air and water cooled rectangular dipoles are used for low and high energy bunch compressors. 17 - degrees dipoles guide the beam towards a dump. The design of these dipoles bases on identical yoke, furnished with adequate coils and vacuum chambers. 45- degrees water cooled dipoles form a transfer section between FEL and Inverse Compton Scattering parts of the linac. Quadrupole poles design assumed parasitic multipoles strengths less than 10-4 relative to the main one. Dipoles field was assumed uniform within 10-4 of B0. Yokes and poles designs have been performed using 2D FEMM code and refined in 3D with Radia. Manufacturing of yokes and coils will be achieved in NCBJ workshop. Currently, the quadrupole prototype has been built and will be mechanically, electrically and magnetically verified.
An 800 MHz, four vane Radio Frequency Quadrupole (RFQ) was designed to accelerate the proton beam to 2 MeV energy at a distance shorter than one meter in KAHVE-Lab,Turkey. A half length test module was also previously produced to investigate the local manufacturability of this high frequency RFQ cavity. The manufactured test module was subjected to mechanical, vacuum and electromagnetic tests to adjust the pressure, EM field and frequency parameters to the desired operational settings. Results from these tests were also used to improve the final manufacturing process for the two modules of the RFQ which has ended successfully in Q4 2022. The finished RFQ, after being fully assembled for the first time, was initially subjected to the vacuum leak tests followed by the low level RF and power tests. The KAHVE-Lab proton beamline is planned to be fully integrated and commissioned by the end of 2023. This study introduces a general framework about the current status of the 800 MHz RFQ, and discusses the ongoing commissioning studies. This project is supported by The Scientific and Technological Research Council of Turkey(TUBITAK) Project no: 118E838
Studies of third-order chromaticity in the LHC during its initial two runs have consistently demonstrated a substantial discrepancy between the expected Q''' at injection and that observed in beam-based measurements. In 2022 during Run 3, for the first time, studies of Q''' have been complemented by measurements of chromatic detuning, being the momentum-dependence of amplitude detuning, and the decapole resonance driving term 𝑓1004. In this paper, these beam-based measurements are presented and compared to the magnetic model. Potential sources of the previously identified Q”’ discrepancy are discussed.
During loss maps performed with beam at injection energy in the LHC with the high octupole and chromaticity settings used for multi-train operation, large beam losses were observed at an injection protection device (TDIS). Although these losses did not present a threat to machine operation or protection, reducing them is of high importance to improve machine performance. Various strategies were developed to mitigate these losses, such as octupole setting optimization at constant Landau damping and vertical tune reduction. Further optimization of collimator settings is also considered. Results of experimental tests and first simulations are reported here together with considerations for the future.
The largest current obstacle to SuperKEKB's luminosity goals is currently beam-related backgrounds occurring during accelerator operation. Thus, understanding the level of these backgrounds is of crucial importance for the future of the facility. In this work, we take advantage of the Belle II Electromagnetic Calorimeter's near-total coverage of the interaction region to create a spatial model of beam-induced backgrounds with the aim of providing fast feedback to improve accelerator conditions.
Skew-octupole errors in the low-beta insertions of the LHC have been measured and corrected during its second operational run either by minimizing feed-down to linear coupling, or directly based on measurement of resonance driving-terms. In 2022 such measurements were repeated in order to prepare a4 corrections for deployment in 2023. During these beam-based studies an impact of the a4 sources could also be observed on the dynamic aperture of driven oscillations with an AC-dipole at $\beta∗ = 30\mathrm{cm}$. In this paper, beam-based studies of a4 errors at 6.8TeV are presented and compared to the expectation from the LHC magnetic model.
One of the most fundamental measurements since the Higgs boson discovery, is the measurement of its Yukawa couplings. Such a measurement is only feasible, if the centre-of mass (CM) energy spread of the e+e- collisions can be reduced from ~50 MeV in a conventional collision scheme to a level comparable to the natural width of the Higgs boson ~ 4 MeV. To reach the desired collision energy spread and improve the CM energy resolution in colliding-beam experiments, the concept of a monochromatic colliding mode has been proposed as a new mode of operation in the FCC-ee. This monochromatization mode could be achieved by generating a nonzero dispersion function of opposite signs for the two beams, at the Interaction Point (IP). Several methods to implement a monochromatization colliding scheme are possible, in this paper we report about the implementation by means of dipoles. More in detail a new Interaction Region (IR) optics design for FCC-ee at 125 Gev has been designed as well as first beam dynamics simulations.
A muon is an elementary particle similar to an electron, with an electric charge of −e and a spin of 1/2; however, the former has a mass 200 times heavier. After the successful generation of muons using a particle accelerator half a century after their discovery, they have become widely used in various scientific fields. A muon beam, however, initially has a large phase-space volume because it is generated as a tertiary beam, which limits potential applications. The muon acceleration and cooling using a cyclotron auto-resonance acceleration scheme are studied by the simulations. In this poster, the results will be presented.
Muons circulating in a muon collider decay and generate neutrinos within a small solid angle, which reach the earth’s surface. One of the challenges of a high energy muon collider is to ensure that showers created by such neutrinos interacting close to the earth’s surface result in very low radiation levels. The neutrino radiation cone from a muon beam without divergence is estimated through a combination of analytical estimates and FLUKA simulations. Such neutrino cones have to be combined with the properties of the lattice to obtain the possible radiation levels at the earth’s surface. Studies of mitigation measures will be presented, combining the installation of the collider deep underground with a careful choice of the orientation, and with periodic variations of the muon beam trajectory either within the machine aperture or by deforming the whole machine in the vertical plane.
The current injector complex design of the FCC-e+e− project consists of e+/e− linacs, which accelerate the beams up to 6 GeV, a damping ring at 1.54 GeV, a pre-booster ring, accelerating the beam up to 16 GeV and a booster synchrotron ring integrated in the collider tunnel accelerating the beams up to the collision energies. The purpose of the damping ring is to accept the 1.54 GeV beam coming from the linac-1, damp the positron/electron beams and provide the required beam characteristics for the injection into the linac-2. The purpose of this paper is to provide a new layout of the damping ring. In this study, the beam parameters are established, including the optics design, layout and consideration for non-linear dynamics optimization.
The FCC-ee could allow the measurement of the electron Yukawa coupling, in dedicated runs at ~125 GeV centre-of-mass energy, provided that the centre-of-mass energy spread, can be reduced to about 5–10 MeV to be comparable to the width of the standard model Higgs boson. The natural collision-energy spread at 125 GeV, due to synchrotron radiation, is about 50 MeV. Its reduction to the desired level can be accomplished by means of monochromatisation, e.g., through introducing non-zero horizontal dispersion of opposite sign at the Interaction Point (IP), for the two colliding beams. This nonzero dispersion in the IP could be generated by different methods, requiring or not modifications of the Final Focus System (FFS). In this paper we report the advances in the implementation of this new possible collision mode, other than the use of dipoles for the implementation of the monochromatization in the FCC-ee Interaction Region (IR).
The Nuclotron-based Ion Collider fAcility (NICA) is under assembling in JINR now. The NICA project goals are providing of colliding beams for studies of hot and dense strongly interacting baryonic matter and spin physics. The NICA Collider accelerator complex involves following accelerators for heavy ion mode: linac HILAC at energy 3.2 MeV/u, superconducting Booster synchrotron at energy up 600 MeV/u, superconducting synchrotron Nuclotron at ion energy 3.9 GeV/n. The NICA acceleration complex in this configuration starts operation with ion beams in beginning of 2022. Fix target experiments at application of BM&N detector were performed during two runs with carbon and xenon ion beams. The assembling of two Collider storage rings will be done in 2023. The status of acceleration complex NICA is under discussion.
To maintain polarization in a polarized proton collider, it is important to know the spin tune of the polarized proton beam, which is defined as the number of full spin precessions per revolution. A nine-magnet spin flipper has demonstrated high spin-flip efficiency in the presence
of two Siberian snakes. The spin flipper drives a spin resonance with a given frequency (or tune) and strength. When the drive tune is close to the spin tune, the proton spin direction is not vertical anymore, but precesses around the vertical direction. By measuring the precession frequency of the horizontal component, the spin tune can be precisely measured. A driven coherent spin motion and fast turn-by-turn polarization measurement are keys to the measurement. The vertical spin direction is restored after turning the spin flipper off. The fact that this manipulation preserves the polarization makes it possible to measure the spin tune during the operation of a polarized collider
such as RHIC and EIC.
As an energy frontier machine, the proposed Super Proton-Proton Collider (SPPC) will have the capability to explore a much larger region of new physics models with center of energy around 125 TeV and circumference 100 km.
The nonlinearity optimization of the SPPC collider ring lattice is essential to get a high peak luminosity and lifetime of the beams. In this paper, a collider ring lattice based on the CDR one will be presented. Then, the nonlinearity of the bare lattice was optimized using Lie map analysis and frequency map analysis. With the optimization, the lattice aberration at the interaction points and dynamic aperture of whole ring were improved.
Finally, the alignment tolerances and field error tolerances for the SPPC are evaluated. The correction scheme of the lattice with errors will be presented.
SuperKEKB suffers from sudden beam loss(SBL) during operation. It causes collimator damage, QCS quench and large beam background to the Bell-II detector. Beam aborts triggered by SBL hinder us from storing large beam current. Since cause of SLB is unclear, we launched an effort to investigate it and consider measures to be taken. In this paper, we discuss phenomena of SBL and various hypotheses to explain SBL.
Ionization cooling is the only suitable approach to reduce the phase space of a muon beam on a timescale compatible with the muon lifetime. The International Muon Col- lider Collaboration gives a target normalized transverse emittance of 25 microns, to be achieved using hydrogen (H) as an absorber and high solenoid fields at low beam energy. On the one hand, the strong focusing suppresses emittance growth due to scattering occurring from the interaction with the absorber’s atomic nuclei. On the other hand, this leads to very small beam sizes and therefore to energy depositions in small volumes leading to high peak energy density. Temperature changes in H cause pressure rises that may damage the beam windows towards the absorber. This work presents the acceptable temperature ranges in liquid H and discusses an alternative method with low density H-gases. It also explores the possible modifications to beam window designs.
During the third run period of the CERN Large Hadron Collider (LHC), as well as for the future High-Luminosity LHC era, luminosity levelling by beta is a key technique to control the pile-up in the high-luminosity experiments ATLAS and CMS while maintaining Landau damping through the head-on beam-beam interaction. This implies changing the machine optics in the interaction regions while keeping high-intensity beams in collision and the experimental detectors in their data taking configuration.
This contribution summarizes the implementation and operational experiences obtained during the first year of operation with beta levelling at the LHC and provides an outlook for the following years, when the beta* levelling range will be further extended.
A non-negligible risk of magnet quenches occurring due to the reduced cleaning performance of the original LHC collimation system with lead ion beams was expected at an energy of 6.8 Z TeV beams. Crystal collimation has therefore been i