Super Tau-Charm Facility (STCF) was proposed as a third-generation circular electron-positron collider in the energy range of 2-7 GeV (CoM) and with a luminosity greater than 5*10^34 cm^-2s^-1 @4 GeV, aiming to explore charm physics and tau physics in the next decades. This presentation will introduce the facility design and R&D efforts for STCF, including the design goal, accelerator and...
SuperKEKB operations resumed in 2024 after the first long shutdown (LS1). A nonlinear collimator was installed to reduce an impedance while keeping background mitigation. Sudden beam loss (SBL) events have been observed when the beam current increases for these years. It is difficult to explain with ordinary beam instabilities, however, several types of monitors have been installed to observe...
The presentation gives an overview of the main technical challenges of the HL-LHC project, describes the key upgrade ingredients and outlines the lates schedule projections.
In 2020 the European Strategy for Particle Physics Update (ESPPU) recommended an Electroweak- and Higgs-factory as the highest priority next collider after completion of the High-Luminosity Large Hadron Collider (HL-LHC), to be followed by a hadron collider with a center-of-mass energy of about 100 TeV. The so-called integrated Future Circular Collider (FCC) program would fulfill this...
The Electron-Ion Collider (EIC) project is well underway at Brookhaven National Laboratory. The EIC aims at achieving peak electron-proton luminosities of up to $10^{34}$ cm$^{-2}$ sec$^{-1}$, covering a wide range of the center-of-mass collision energy, as well as a high level of polarization. The project configuration has recently been optimized to relocate the Rapid Cycling Synchrotron into...
The Electron-Ion Collider (EIC) at BNL is designed to provide a peak luminosity of 10^34 cm^-2 sec^-1 (electron-proton equivalent) in collisions between polarized electrons and heavy ions or polarized protons. To achieve this high luminosity, high beam currents in a large number of bunches are required, and ion beams with unequal transverse emittances need to be generated and accelerated....
In response to the beam characteristics and measurement requirements of the injector at the next-generation electron-positron collider, the Super Tau-Charm Facility (STCF), a method for measuring bunch length and bunch charge using a cavity is proposed. This report presents the basic principles and system configuration of the cavity-based beam monitoring technique. The design parameters and...
The bunch-by-bunch feedback system is now an key function in high-current, multi-bunch storage rings to suppress coupled-bunch instability and/or to reduce the effects of injection vibration. In high-luminosity e+e- colliders such as SuperKEKB, strong beam-beam interactions occur due to collisions, so the side effects of the feedback system can have a large impact on the luminosity. In this...
The Super Tau-Charm Facility (STCF), proposed by the University of Science and Technology of China, represents the next generation of electron-positron colliders. With a target luminosity exceeding 5×10^34 cm-2s-1, the STCF aims to achieve approximately two orders of magnitude higher luminosity compared to the current BEPCII. To reach such high luminosity, a combination of large Piwinski angle...
The proposed electron-positron Future Circular Collider (FCC-ee) is planned to achieve unprecedented high luminosity, enabling answers to fundamental questions in high-energy physics. Magnets field imperfections and misalignments significantly impact beam dynamics and can strongly affect the collider's performance. In this contribution, we present the current status of a developed correction...
Beam profile diagnostics will play a crucial role in the commissioning and efficient operation of the electron-positron Future Circular Collider (FCC-ee).
This talk presents the current status of feasibility studies for the transverse diagnostics systems. Non-invasive techniques are essential to prevent beam perturbations during regular physics operation.
As is customary in high-energy...
Relativistic charged particles moving near a dielectric medium emit radiation through a process similar to classical in-medium Cherenkov radiation. The distinctive features of this effect—such as a well-defined and high emission angle, along with sensitivity to beam parameters—make it a promising candidate for a non-invasive diagnostic technique. However, theoretical models describing the...
The Belle II experiment at the SuperKEKB energy-asymmetric $e^+ e^-$ collider is a substantial upgrade of the $B$ factory facility at the Japanese KEK laboratory. Since the year 2019, Belle II has recorded close to 600 fb$^{-1}$ at the center-of-mass energy of the $\Upsilon(4S)$ resonance. Together with the Belle data set, this is by far the world-largest sample of electron positron collision...
Electron-positron collider experiments, such as BESIII and Belle (II), along with future facilities like the Super Tau-Charm Factory (STCF), will serve as improtant laboratories for studying charm physics. BESIII operates near the threshold energy region, where it collects substantial data samples of charmed and anti-charmed hadron pairs. The proposed STCF aims to be a third-generation...
The Future Circular Collider electron-positron (FCC-ee) injector linacs and positron source are critical components for delivering high-quality beams to the collider. This work presents studies on key dynamic effects influencing beam stability, including single- and multi-bunch instabilities. A detailed analysis of multi-bunch beam loading is conducted, considering trains of arbitrary bunch...
The Circular Electron Positron Collider (CEPC) is a 100-km electron-positron collider designed as a Higgs factory. Its accelerator complex comprises a 30-GeV Linac, a full-energy booster, two collider rings, and several transport lines. To mitigate the challenges associated with low-energy design for the booster and to manage costs effectively, the Linac is tasked with delivering electrons and...
The talk will review prospects of precision EW and QCD studies at $e^+e^-$ collider experiments at the Z-pole and beyond including FCC-ee, CEPC, ILC and CLIC.
Focus will be made on observables used for the electro-weak fits and basic QCD studies such as strong coupling constant, event shapes and jets. A short introduction on theoretical aspects will be given, together with the...
The proposal for a new generation high-luminosity electron-positron collider, the Super Tau-Charm Facility (STCF), has been put forward in China. The STCF is expected to achieve a luminosity greater than 0.5×10^35 cm^-2 s^-1 and operate within a center-of-mass energy range of 2 to 7 GeV. Considering the design challenges of the STCF collider ring, swap-out injection has been suggested as one...
The Advances in High-Intensity Positron Source Physics and Technologies (AHIPS-2024) workshop, held from October 16 to 18, 2024, at IJCLab, Orsay, France, brought together experts from the world-wide accelerator community to discuss the latest developments in high-intensity positron sources. The workshop covered both polarized and unpolarized positron sources for current and future linear...
Experiments at e+e- colliders have historically been succesful in the discovery of new particles. During the last 20-30 years many flavor factories operated at energies from 1 GeV to slightly above 10 GeV. This range is particularly suited to search for the existence of a light dark sector. I will present results from recent searches, especially from the Belle II experiment, for dark photons,...
Intense positron source is a one of the key component for the next electro positron collider. Recently, several groups actively discuss and develop such positron sources for FCC, CEPC and ILC. On the other hand, basic design of positron source have not changed for more than 30 years since the one developed for the SLC. In addition, only a few positron sources are in operation now. In this...
The next generation of lepton colliders demands machine luminosities in the range of 10³⁴ to 10³⁶ cm⁻²s⁻¹, requiring electron sources capable of delivering bunch charges of several nanocoulombs at injection rates of tens to hundreds of bunches per second. Achieving such high charge levels requires careful optimization of the electron source to maximize injection efficiency. This talk explores...
The vacuum system of the CEPC accelerator comprises the LINAC, Booster, collider rings, and transport lines. The Technical Design Report (TDR) was published in 2024, and the Engineering Design Report (EDR) has been under development since 2024, with reviews by IARC. A production line for massive NEG coating and heating spraying of vacuum chambers will be developed in the next two years to...
Super Tau Charm Facility (STCF), a factory producing massive tau lepton and hadrons, to unravel the mystery of how quarks form matter and the symmetries of fundamental interactions, is under design in China. The STCF is designed to have energy of 2-7 GeV and luminosity higher than 0.5x1035 cm-2s-1 with circumference about 800-900 m. There are two dual-aperture final focus insertion region...
This talk will overview two instabilities in the accelerator’s vacuum chamber that are in a boundary between an accelerator lattice design and solutions for beam vacuum design.
Ion induced pressure instability is a threat for positively charged beams. Modelling of this potential problem is essential for a proper vacuum design for its mitigation. The modelling requires knowledge of various...
The Electron-Ion Collider (EIC) will be a new, state of the art nuclear physics research facility that is currently approaching the preliminary design milestone. This facility will be built at the US Department of Energy’s Brookhaven National Laboratory located in Upton, New York. The EIC will collide high energy (up to 18 GeV) polarized electrons with polarized protons (up to 275 GeV) and...
SuperKEKB is an energy-asymmetric double-ring collider with a 7 GeV electron beam and a 4 GeV positron beam. An extremely small beta function at the interaction point (IP) and low emittance are necessary to achieve a peak luminosity that is an order of magnitude higher than that achieved by the KEKB. A final focusing superconducting magnet system provides the focusing magnetic field required...
The electron cloud effect (ECE) poses challenges in high-intensity proton and positron rings. A potential solution is to prepare a surface with low secondary electron yield (SEY) on the inner walls of beam pipes.
In the Low Energy Ring (LER) of SuperKEKB, TiN coating and grooved structures have been applied to reduce the SEY of the beam pipes. From 2017 to 2023, we explored a commercial...
The Electron-Ion Collider (EIC) aims at luminosities of up to 10^34 cm^-2 sec^-1. This is accomplished by colliding large numbers of high intensity bunches in a low-beta interaction region with a total crossing angle of 25 mrad. The physics program of the EIC requires high forward acceptance, which necessitates large apertures of the forward hadron magnets to transport scattered particles to...
Chiral Belle, put forth in a Snowmass White Paper*, involves a modest upgrade to the SuperKEKB e+e- collider at KEK to enable the existing Belle II detector to explore topics in precision electroweak physics with longitudinally polarized electrons. Spin-dependent observables provide unique, powerful alternative probes for entirely new discovery windows to address exciting hints of physics...
The SuperKEKB accelerator at the Belle II experiment has achieved record luminosities, but increasing luminosity is hindered by Sudden Beam Loss (SBL) events, which can damage both the accelerator and detector components. To address this issue, we have developed and implemented advanced beam diagnostic and beam abort systems.
High-speed loss monitors, including PMTs and Electron Multiplier...
The current achieved highest luminosity at SuperKEKB is only one-tenth of the design value, and beam injection is one of the most serious issues in achieving the target luminosity. Recent operations in both the HER and LER rings have shown insufficient injection efficiencies and detector backgrounds. The achieved injection efficiency falls short of the required level, sometimes leading to...
Belle II is the only particle physics experiment at the SuperKEKB $e^+e^-$ asymmetric-energy collider. While SuperKEKB achieved a new world record for peak luminosity, $5.1\times10^{34}\,\textrm{cm}^{-2}\,\textrm{s}^{-1}$, in 2024, the background conditions at the Belle II detector became more challenging compared to previous run periods. In this presentation, we share our experience with...
The FCC-ee is a next-generation high-luminosity electron-positron collider designed for beam energies between 45.6 and 182.5 GeV. Achieving its ambitious performance objectives relies on precise optics tuning. This study addresses the challenges of magnet misalignments, gradient errors and stringent alignment tolerances in the Interaction Region (IR). Utilizing the pyAT framework, correction...
The machine-detector interface (MDI) issues are one of the most complicate 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 machine will operate at different beam energies, therefore, a flexible interaction region design will be...
The Future Circular Collider electron-positron (FCC-ee) is a proposed high-energy lepton collider that aims to reach unprecedented precision in the measurements of fundamental particles. However, several beam related processes produce particles in the Machine-Detector Interface (MDI) region, which can adversely affect the measurements' accuracy. This contribution presents the status of the...
The International Linear Collider(ILC) is a large accelerator project using many superconducting cavities and magnets. Therefore, huge cryogenic systems are required. The early design of the ILC was published as the Technical Design Report(TDR) in 2013, however, some changes have been accepted since then. The biggest change is that the collision energy was decreased from 500 GeV to 250 GeV at...
The Super Tau-Charm Facility (STCF), proposed in China, is a new-generation high luminosity e+/e− collider in the low-energy region of 1-3.5 GeV. To achieve the target luminosity of larger than 5×10^34 cm^−2s^−1, a large crossing angle and crab-waist correction scheme is applied. It is well-known that nonlinearity within the interaction region (IR), particularly due to crab sextupoles,...
The Electron-Ion Collider (EIC), under construction at BNL, is a groundbreaking facility designed to explore the fundamental structure of matter. By colliding high-luminosity polarized electron and ion beams, the EIC will probe the spin, mass, and spatial distributions of quarks and gluons, addressing key questions in QCD. However, mitigating beam-induced backgrounds remains a critical...
The FCC-ee Interaction Region is compact and complex, aimed to reach the highest luminosities at all centre-of-mass energies, from the Z pole to the t-tbar threshold. Its layout must integrate accelerator components such as lightweight and actively cooled beampipes, superconducting IR-magnets, bellows, remote vacuum connection, beam and detector diagnostics, vertex and luminosity detectors....
There is no doubt that global warming is accelerating due to greenhouse gas emissions from human activities. All industries are now required to work toward achieving carbon neutrality by 2050. Accelerator facilities are no exception. In particular, life cycle assessment, including construction, operation, and decommissioning periods, is necessary to achieve carbon neutrality. Researchers...
New e+e- accelerator designs plan to have polarized beams. Precision detectors located very close to the beam envelope will be needed to measure the polarization of the stored bunches. In addition, the new designs call for multi-Ampere stored beam currents. This will move electron and positron storage ring designs into new territory with the need of detectors this close to these high-current...
Polarized lepton beams are essential for the physics program of the Circular Electron Positron Collider, their applications include precision beam energy calibration based on resonant depolarization technique and longitudinally polarized colliding beams. To this end, we proposed a scheme including generating polarized beams from the source, transmitting throughout the injector chain, and...
The European Laboratory Directors Group that coordinates European programme of accelerator R&D, took recently the decision to establish a working group on sustainability assessment of future accelerators. Working group mandate is to develop guidelines and a minimum set of key indicators pertaining to the methodology and scope of the reporting of sustainability aspects for future HEP...
SuperKEKB accelerator is one of the world's highest luminosity collider with electron-positron asymmetric collision, which is aiming at 10 times higher luminosity than that KEKB achieved. In order to obtain the target luminosity, it is designed to store the unprecedented high current beams of 2.6 A and 3.6 A in the electron and positron rings, respectively. In this talk, concerns about RF...
Abstract to be delivered soon (Needed ID for registration)
Precise determination of the center-of-mass energy at the Future Circular Collider (FCC-ee) operating at the Z and W resonance energies relies on resonant spin depolarization techniques, which require a sufficient level of transverse beam polarization in the presence of machine imperfections. In this study, the FCC-ee lattice is modeled and simulated under a range of realistic imperfections,...
The HL-LHC beams are accelerated to their nominal energy of 7 TeV by the existing 400 MHz superconducting RF system of the LHC. A novel superconducting RF system for transverse deflection (aka crab cavities) will be used to compensate the geometric loss in luminosity due to the non-zero crossing angle and the extreme focusing of the bunches in the HL-LHC.
The highlights of the crab cavity...
In order to perform the precise energy calibration for the Z and WW modes of the FCC-ee machine, the use of Resonant Depolarization (RDP) method on a set of non-colliding polarized bunches is foreseen. To track the polarization state of these bunches while scanning the depolarization excitation frequency a Compton Polarimeter will be deployed on both colliding beams.
The most recent...
Beam dynamics during acceleration are inherently sensitive to numerous external factors, particularly within superconducting linear accelerators. In such systems, the high-Q superconducting RF cavities are especially vulnerable to instabilities caused by unforeseen disturbances, which can significantly degrade beam quality or even lead to beam loss. The low-level RF (LLRF) control system,...
Chiral Belle is a project proposed to expand the capabilities of SuperKEKB and the physics goals of Belle II by injecting polarized electrons into the High Energy Ring (HER) to make left-right asymmetry measurements. As part of the R&D and feasibility studies of this project, we are developing a proposal to inject and transport transversely polarized electrons into the HER and measure the...
A compact TM020-mode RF cavity has been proposed and studied by KEK and RIKEN for storage ring of Nano-terasu facility. However, the leakage power of the accelerating mode into the coaxial slots is an issue to limit its performance. This paper presents an improved TM020-mode cavity in order to solve this issue. By employing el-liptical choke, the leakage can be significantly reduced. Harmful...
The Electron-Ion Collider (EIC) at Brookhaven National Laboratory will collide polarized protons between 41 and 275 GeV against polarized electrons ranging from 5 to 18 GeV, achieving luminosities up to 10^34 cm^{-2} s^{-1}. We review the factors impacting the expected polarization transmission and lifetime for the EIC's Electron injector systems, Storage Ring (ESR), the Hadron injector...
The free spin precession (FSP) method is considered as an alternative to the well-known approach based on the use of the resonant depolarization scanning procedure (RDP). The main advantage of FSP over RDP is that the spin tune will be determined directly from the Fourier spectrum of the signal from the Compton polarimeter measuring the oscillations of the longitudinal spin component. This...
The International Linear Collider (ILC) is a future electron-positron collider based on superconducting radio frequency (SRF) technology, planned to be situated in Japan. In this contribution an introduction to the ILC is given, followed by a report on the status of the ILC Technology Network (ITN). Furthermore, an overview of the current cryomodule development at KEK as well as of the...
The ultimate goal of the Future Circular electron-positron Collider is performing particle physics experiments at an unprecedented precision from the Z-pole up to above the top-pair-threshold. This demands, among others, an excellent knowledge of the center-of-mass energy and, hence, the beam energies. By depolarizing polarized pilot bunches with a RF-kicker and recording the change of...
Yun Luo, F. Willeke, Yue Hao, J. Qiang, D. Xu, M. Blaskiewicz, C. Montag
The Electron-Ion Collider (EIC), to be constructed at Brookhaven National Laboratory, will collide polarized high-energy electron beams with polarized hadron beams, achieving luminosities up to 1 × 10^{34} cm^{−2} s^{−1} in the center-of-mass energy range of 29-140 GeV. To achieve such high luminosity, we adopt high...
High-efficiency klystrons are a key component for the operation of next-generation particle colliders such as the Future Circular Collider - electron-positron (FCC-ee), the Compact Linear Collider (CLIC), the Large Hadron Collider (LHC), and the Circular Electron Positron Collider (CEPC). These high-power RF sources provide the essential energy required for particle acceleration and beam...
A nonlinear collimation system (NLC) was introduced into the SuperKEKB low energy ring (LER), a 4 GeV positron ring, during the first long shutdown (LS1) to reduce the impedance in the vertical direction. We built the impedance model of the LER after LS1 and simulated the tune shift as a function of the bunch current and the single-bunch collective instability for this model using PyHEADTAIL....
The beam stability in the FCC-ee collider is highly sensitive to impedance sources. Developing a flexible and comprehensive impedance model is crucial for accurately evaluating and mitigating instabilities as machine parameters evolve.
This study investigates the current impedance budget of FCC-ee, with a particular focus on the geometric effect of the collimation system, identifying it as a...
BEPCII is a double-ring collider operates in the decay mode, as beam currents decrease over time, the beam orbits need to be continuously adjusted to maintain the optimum collision conditions. This job was primarily performed manually, with operators scan three offset knobs (x, y, y') based on the luminosity. There is a critical need to implement advanced automated control method. However, the...
The Future Circular Collider (FCC) study at CERN is developing designs for the next generation particle colliders to follow on from the Large Hadron Collider after its High-Luminosity phase. A new tunnel of about 90 km circumference would Initially house an electron-positron collider, the FCC-ee, with a research programme of 15 years followed by a hadron collider, the FCC-hh, with a programme...
VEPP-2000 electron-positron collider operating in the beam energy range of 150-1000 MeV is the only machine originally designed to exploit Round Beams Concept which results in significant beam-beam limit enhancement. After long shutdown for injection chain upgrade VEPP-2000 resumed data taking with luminosity limited only by beam-beam effects.
Thanks to extensive and thorough machine tuning...
The Super Tau-Charm Facility (STCF) is designed to achieve a peak luminosity of $1 \times 10^{35}\ \text{cm}^{-2}\text{s}^{-1}$ using the crab waist (CW) collision scheme. Its design is currently underway, led by the USTC team in China. In this study, we investigate the impact of beam-beam effects on the STCF design by performing both weak-strong and strong-strong beam-beam simulations, with...
The FCC-ee collider requires strong focusing and small beam sizes at the interaction point (IP) to achieve its unprecedented luminosity. Magnet misalignments and gradient errors will perturb the optics at the IP, leading to beam size growth, and making it difficult to reach the collider’s luminosity goals. Therefore, tuning tools are essential for correcting these aberrations during operation....
There are several issues to limit the luminosity performance of SuperKEKB. We discuss mechanism of Sudden Beam Loss (SBL), -1 head-tail mode instability related to bunch-by-bunch feed back system, and coherent and incoherent beam-beam phenomena.
The SuperKEKB accelerator has been studying accelerator operations using machine learning since 2022. Machine learning has been introduced in Linac to control the orbit of electron and positron beams to achieve highly efficient generation and transport of electron and positron beams downstream of Linac. Similarly, machine learning has been applied to orbit control to suppress emittance...
The beam-beam interaction related studies at CEPC are presented. The beam-beam limit, combined effects of beam-beam and longitudinal/transverse impedances, and mitigation study of coherent beam-beam instability are discussed. The effects of optics error on beam-beam performance are also presented. Some simulation on crosstalk between beam-beam interaction and lattice is also shown.
The instability of the electron beam interacting with the residual ions in the EIC electron storage ring (ESR) was identified as a concern during the early design stages. Both the multi-turn (with ion accumulation) and single-turn (also known as “fast-ion” type) versions of the instability could potentially lead to large oscillations of the beam centroid, degrading the collision rate and...
The nano-beam scheme allows the vertical beta function at the interaction point (IP) to be much smaller than the bunch length. The vertical beta function and the beam size at the collision point realized at SuperKEKB are the smallest in the world among colliders. As the result, the luminosity can be achieved higher than conventional colliders utilize a head-on collision or a smaller...
Beam-dust interaction is discussed. Heating, ionization, melting, fusion and evaporation precesses are simulated in interaction with beam. It is shown that beam is aborted by interaction with the charged cloud of dust and evaporated ions.
