Laser-to-RF synchronization plays a crucial role in various scientific and technological domains. It is instrumental in generating high-quality electron beams, producing high-performance FEL pulses, ex-ploring ultrafast dynamical processes, and achieving precise measurements and transmission. Passively mode-locked femtosecond lasers are known for their exceptionally low noise characteristics,...
We present the experimental results of the longitudinal phase space measurement using the well-known wakefield deflector driven by the dechirper. When the electron bunch travels through the dechirper, electrons at the head of bunch generate the strong transverse wakefield which forces the trailing electrons to be transversely streaked. In such a way, the temporal structure of bunch can be...
BEPCⅡ is a double ring e+ e- collider running in the tau-charm energy region. We proposal reusing the beamline of a dismantled wiggler magnet to implement a Compton polarimeter detecting scattered γ photons, to measure the self-polarization of the electron beam at BEPCⅡ. As a testbed for future colliders like the CEPC, this would enable resonant depolarization，and thus provide precision beam...
Bunch shape monitors based on the transverse modulation of low energy secondary emission elec-trons, will be used in the measurement of longitudinal beam density distribution in the upgrade of CSNS-II linac. A test bench for commissioning the 324MHz RF deflectors used in BSM has been built in the laborato-ry, which consists of a Kimball E-gun, a vacuum chamber for electron optics, an RF...
The North Area facility (NA), built in the 1970s at CERN, hosts several secondary beam lines for a large variety of physics experiments: Neutrino Platform, Dark matter, high energy physics, R&D, detector validation etc. 400 GeV/c primary proton beams, extracted from the SPS ring, are split along the transfer lines to fire on 4 targets and serve the users with secondary particles such as e-,...
The jitter of the beam arrival time can significantly impact the synchronization between the seed laser and the electron beam, which will constrain the brightness and stability of the FEL. It is one of the important parameters for beam diagnostics. To align with the SHINE's (Shanghai HIgh repetition rate XFEL aNd Extreme light facility) requirements of a 1MHz repetition rate and a dynamic...
The High Energy Photon Source (HEPS) is a fourth-generation light source with a beam energy of 6 GeV currently under development by the Institute of High Energy Physics. The Beam Loss Monitor (BLM) system is designed for monitoring beam losses during machine commissioning. Two types of beam loss monitors have been installed in both the booster and storage ring. This paper introduces the...
The Novosibirsk Free Electron Laser (NovoFEL) is a powerful source of narrow-band terahertz and infrared radiation, operating at the Institute of Nuclear Physics of the Siberian Branch of the Russian Academy of Sciences (INP SB RAS). It is based on an accelerator-recuperator system and is one of the main user facilities of the Siberian Synchrotron and Terahertz Radiation Center. In recent...
Beam based alignment is a well-known technique for obtaining a small emittance beam which is critical in an injector of an accelerator or a matching section between two accelerators. The simplest beam based alignment can be performed with a corrector, a quadrupole, and a beam position monitor. This work presents a beam based alignment technique with double correctors located before the...
Beam loss is a critical challenge in the physics design of high power superconducting proton linacs. The challenge is even more acute in linacs that feature high peak intensity and low energy, which has strong space charge effect and RF nonlinear force. In this paper, we study how to achieve a high transmission rate for beam halo particles, commonly a major source of beam loss, via beam halo...
We are developing a system of beam loss monitor at the Aichi Synchrotron Radiation Center, AichiSR in Japan, for accelerator operation stable. AichiSR is a light source mainly for industrial applications with a 1.2 GeV electron storage ring, the circumference of 72 m. It is operated with a beam current of 300 mA at all times by top-up injection. The beam loss measurement uses PIN photodiode...
The Energy Recovery Linac (ERL) serves as a primary means to simultaneously achieve high energy utilization efficiency, high average beam current, and high-brightness electron beams. The Chinese Academy of Engineering Physics’ Infrared Terahertz Free-Electron Laser (CAEP IR-THz FEL) aims to produce FEL light within the 0.1-125 THz spectrum with updated beam energy and undulators. Another goal...
The final-focus solenoids of the round-beam e+e- collider VEPP-2000 can cause stopbands in the betatron tune plane. This specific stopband domain limits the available tune space in the most important region above the integer tunes. We present a study of the combined effect of coupling resonances caused by the decompensated solenoids and the integer-tune parametric resonances. The results are...
DAFNE is an electron-positron collider in operation at INFN-LNF since 2001. Bunch-by-bunch feedback systems installed in each of the two rings allow to store high-intensity and stable beams, by counteracting coupled-bunch instabilities. The feedback systems can be also used as a diagnostic tool able to measure beam parameters which are significant for the evaluation of the instabilities. In...
Accelerators at J-PARC, a high-intensity proton accelerator facility, consists of a 400 MeV linac, 3 GeV RCS, and 30 GeV MR. The RCS is aiming for steady operation with output beam power of 1 MW, while the MR has achieved its initial target of 750 kW by shortening its operating cycle, and further beam tunings and developments are underway to achieve the next target of 1.3 MW. At J-PARC, it is...
Providing 10 to 60 MeV proton beams, the PREF (Proton Radiation Effects Facility) is dedicated to the displacement damage effect experiments. The slow extracted beams from the synchrotron are delivered to two experimental terminals, which required the flux as constant as possible. To characterize the slow extraction parameters, scintillators and ionization chambers are equipped in the...
Beam lifetime measurements are an important tool to characterize the key storage ring and machine performance parameters. They are usually derived from the dc current transformer (DCCT) data, and their accuracy depends on DCCT noise and data duration period. However, accurate dc current and fast lifetime determination are in contradiction and have to be balanced carefully. In this...
In order to achieve nondestructive measurement and feedback of beam energy and energy spread for high repetition frequency Linac, an eight-stripline beam energy and energy spread monitor have been designed to replace destructive monitor sunch as fluorescent screen. Different from the conventional evenly arranged stripline structure, an unevenly arranged stripline layout is proposed to improve...
The Large Hadron Collider (LHC) is equipped with NiTb superconducting magnets operating at the cryogenic temperature of 2.9 K. A tiny fraction of proton beam at 7 TeV impacting the magnet coils has the potential to generate enough heat, leading to the loss of superconductivity in the magnets. Consequently, it is imperative for machine performance to detect such beam losses before the quench...
The electron current measurement module is a key component of the superconducting cryomodule testing platform. Serving as a vital monitoring signal device within the coupler interlock system, this module monitors the electron cloud of high-energy power couplers and waveguide systems to ensure their effective protections. This article details the design and performance testing of the electron...
The Cryogenic Current Comparator (CCC) is a superconducting SQUID-based device, which measures extremely low electrical currents via their azimuthal magnetic field. Triggered by the need for nA current measurement of slow extracted beams and weak beams of exotic ions in the storage rings at FAIR and CERN, the idea of the CCC as a diagnostics instrument has been revitalized during the last ten...
The CSNS-II linear accelerator upgrade will adopt superconducting accelerator structures, with the beamline enclosed in low-temperature modules. Detection of beam loss can only be done on the outer surface of the low-temperature modules. The CSNS-II accelerator plans to use a parallel plate multi-electrode ionization chamber as the beam loss monitor (BLM) probe for the superconducting section....
Non-intrusive cavity beam diagnostic devices offer advantages such as high induced signal and sensitivity. The size of the resonant cavity is inversely related to its operating frequency, resulting in an increase in size at lower operating frequencies, thus limiting its applicability.
Therefore, exploring how to modify the cavity structure to regulate its internal electromagnetic field...
Accelerator technology development requires an increase in the precision of both the manufacturing of magnetic elements and their positioning during accelerator installation. In order to monitor the quality of the magnetic elements created, various methods are used. Most of the methods involve the use of precision stands, so magnetic elements are typically measured immediately after production...
The Rare Isotope Accelerator complex for ON-line experiments (RAON) is a heavy ion accelerator with a maximum beam power of 400 kW. The Beam Loss Monitor (BLM) system has been developed to investigate the amount of beam loss in the accelerator. BLM system utilizes current read-out system, analog pre-amp circuit and BLM devices. These devices comprise three types: Proportional Counter, Plastic...
The beam loss measurement system is an important beam measurement device in the CSNS accelerator, used to measure the beam loss signals along the entire accelerator to monitor the beam status. In CSNS, the beam loss measurement system uses NI PXIe-6358 acquisition card combined with self-developed front-end analog electronics. In the RCS of CSNS-II, a new beam loss electronics based on zynq...
A bunch-by-bunch beam monitor electronics for High Energy Photon Source (HEPS) was designed. The hardware of electronics consists of analog signal acquisition board and digital signal processing board. The software consists of underlying firmware and application software. The sampling frequencyis 500 MHz, and the bandwidth is 1 GHz. The electronics digitizes four analog signals from BPM probe,...
The Shanghai soft X-ray Free-Electron Laser facility (SXFEL) is a fourth-generation linac-based light source, capable of producing X-ray pulses with duration of tens of femtosecond. The photocathode laser and the seed laser for external seeding FEL therefore have tight requirements for relative arrival time to the machine and electron bunch. To reach required energy and wavelength to drive...
The article describes the BLM system of the Novosibirsk Free Electron (NovoFEL) microtron. Cherenkov radiation detectors are used to monitor beam losses. When beam of electrons hit the wall of the vacuum chamber, they create a shower of secondary electrons that fly out of the chamber and pass through the detector material, creating Cherenkov radiation in the process. The facility uses two...
The energy characterization of an RF ion beam, generated by an inductively coupled plasma (ICP) RF ion source, has been conducted using a spherical electrostatic energy analyzer. The RF ion source, operating at an applied frequency of 13.56 MHz and a power level of 300 W, was assessed in both pulse and continuous modes. The ion energy spectrum of the hydrogen beam was meticulously measured...
The knowledge of the longitudinal bunch shape is of high interest to accelerator performance optimization and advanced beam application. Attracted by the ability to continuously monitor the beam in real time, there is always a demand for bunch-by-bunch and non-invasive diagnosis. However, such diagnosis is difficult to achieve for proton beam with high intensity and high repetition. Using the...
All CERN circular accelerators are equipped with Base Band Tune (BBQ) measurement systems, based on the direct diode detection technique, allowing to measure the tunes of hadron beams by employing their residual betatron oscillations or very small external excitation. In the framework of the Future Circular Collider (FCC) project, a study was launched to optimise such a system for operation...
RAON is a multi-purpose accelerator facility that can accelerate various heavy ion beams and exotic rare isotope beam, with a maximum energy of 200 MeV/u for uranium beams. Abnormal behavior or excessive instability of the device may result in damage to the device when an ion beam is irradiated onto the device. A fast protection system has been built, which quickly blocks the beam and prevents...
VEPP-4M collider and KEDR detector are going to measure precisely $\Upsilon$(1S) mass and leptonic width.
In this experiment the electron beam energy is precisely measured using resonant depolarisation tecnhique at "Laser Polarimeter" facility.
The electron beam polarisation degree is measured using Compton backscattering with accuracy of 5\% in 100 seconds.
The beam energy is measured...
Modern accelerator-based light sources rely on short bunches to generate intense photon pulses. To achieve this, the electron bunches from the accelerator need to be compressed longitudinally in a magnetic chicane. A valuable tool for the measurement of the signal in the bunch compressor is the use of broadband EM-detectors covering a spectral range from few 100 GHz up to THz frequencies. With...
This paper proposes a longitudinal phase space measurement and reconstruction technology of particle beam in a storage ring. The technology collects and analyzes the beam injection signals by a high-speed oscilloscope, so as to extract the phase and beam length information of the injected beam. The length of a single data collection covers several thousand circles, the measurement accuracy of...
Beam orbit stability is a crucial indicator that can be used to evaluate the performance of a synchrotron radiation source. It can be improved through precise orbit measurement with beam position monitors (BPMs) and appropriate orbit feedback. The move-ment of BPMs directly affects the measurement of the beam orbit and indirectly affects the beam orbit through orbit feedback (OFB) system. Two...
The High Intensity Heavy-ion Accelerator Facility (HIAF), currently under construction, is a complex machine that couples a Continuous Wave (CW) superconducting ion Linear accelerator (iLinac) with a high-energy synchrotron to produce various stable and radioactive intense beams with high energies. The machine has a versatile operation mode which requires a high flexibility and reliability to...
Dipole magnet vacuum chambers are among the critical and costly components of rapid-cycling accelerator facilities. Alternative approaches to traditional ceramic chambers have been explored for the implementation of fast-ramping dipole-magnet vacuum chambers, including thin-wall metallic beam pipe chambers strengthened with transverse ribs. Here, we report a novel 3D-printed titanium alloy...
The demonstration of a 100 mA, 4.6 MeV superconducting radio frequency linear electron accelerator, based on conduction cooling and developed by the Institute of Modern Physics (IMP), aims to validate the feasibility of stable beam commissioning in a liquid helium-free 5-cell-$\beta$opt=0.82 Nb3Sn elliptical cavity, and to offer guidance for subsequent industrial applications. The beam energy...
Accurately measuring the beam phase is critical when determining the ideal RF cavity parameters for beam acceleration. In the past, only Fast Current Transformers (FCTs) were used to measure the beam phase. However, with the upcoming upgrade of the MEBT section for the CSNS-II project, shorted stripline-type BPMs will now be utilized to measure beam position, phase, and energy. LIBERA...
H- ion source produces mixed beam of H- and electrons. Usually, a bending magnet is needed to measure the contents of mixed beam. However, bending magnet is generally lacked in H- machine, because bending magnet increases the transport line length, leading to more serve decline of H-. How to measure the H- content in mixed beam without the help of bending magnet is worthy to be studied. In...
The Novosibirsk Free Electron Laser (NovoFEL) facility consists of three free electron lasers (FELs) installed on different tracks of the Energy Recovery Linac (ERL). These FELs share a common acceleration system, which allows for the generation of high average electron currents, typically around 10 mА. This high current facilitates the production of significant average FEL powers, often...
The method of varying the strength of the corrector magnet installed upstream and minimising the position variation in diagnostics located downstream is widely used for identifying the centre of the magnetic field produced by a quadrupole magnet. However, in the case of a solenoid magnet, unlike a quadrupole magnet, it is not suitable to apply the variable separation method in the x-y...
More than 4000 Beam Loss Monitors (BLM) systems are operating at CERN. About 93% of them are installed in the LHC machine. The Ionisation Chambers (IC) are the part of the system where the lost beam particles ionise nitrogen gas in a chamber with electrodes at high voltage. The resulting current indicates the quantity of the beam loss. In the last 20 years, all BLM ICs were produced in...
Online beam monitoring is crucial for enhancing the efficiency and availability of high-power accelerator operations. While real-time monitoring of transverse beam parameters is commonly employed in modern accelerators, there is a scarcity of online measurement techniques for longitudinal beam characteristics. We are currently developing an online tool for measuring fundamental longitudinal...
Phase stable coaxial cables are widely used for the transmission of reference signals, monitoring signals and control signals in accelerator Low-level RF, beam measurement and control systems, especially for high requirements of time/phase stability. The change in ambient temperature will change the electrical length of the coaxial cables leading to the transmission time and signal phase...
The timing jitter of electron bunch will affect the temporal and power stability of FEL, as well as the resolution of pump-probe experiment at FELs. In order to improve the time stability of electron bunch by beam feedback, Shanghai high-repetition-rate XFEL and Extreme light facility (SHINE) will employ the Electro-optic Bunch Arrival Time Monitor (EOBAM) to accurately measure the electron...
With the refurbishment completed, the optical beamline delivers all the required diagnostics. This paper reports on their status focusing in particular on the R&D beamline branch. The additional branch is equipped with programable mirror and lens position controllers allowing elaborate optical optimisation. This system is used for educational purposes and for improving the source point imaging...
The fourth-generation synchrotron light source Siberian Ring Photon Source (SKIF), located in Novosibirsk, Russia, underwent the tuning of its linear accelerator segment successfully. By deploying a designed beam diagnostic system, crucial parameters of the beam including beam transverse and longitudinal dimensions, energy spread, emittance, and current, were accurately measured. To achieve...
Insertion devices (IDs) are currently being installed at the SIRIUS storage ring to provide photon beams for upcoming high-brilliance beamlines. A fast orbit distortion detection system is imperative to safeguard critical vacuum chambers located near the straight sections of the IDs. In November 2023, an in-house Delta undulator was successfully installed, and a fast orbit interlock protection...
The non-uniformity, longitudinal oscillations, and space charge effects in a multi-bunch filled electron stor-age ring can lead to significant deviations in the meas-urement of longitudinal beam parameters. Selecting a single bunch for measurement can effectively improve the measurement accuracy of longitudinal beam parame-ter, under normal multi-bunch operation mode. This pa-per introduces an...
LumiBelle2 is a fast luminosity monitoring system designed to do fast luminosity feedback and machine tuning and beam parameters studies for SuperKEKB. It uses sCVD diamond detectors placed in both the electron and positron rings to measure the Bhabha scattering process at vanishing photon scattering angle. Two types of online luminosity signals are provided, Train-Integrated-Luminosity...
The Iranian Light Source Facility, ILSF, is under design as a 3 GeV synchrotron light source. The storage ring of ILSF with a 528 m circumference and NEG-coated vacuum chamber is used to achieve the desired vacuum level. In this paper, the monitoring system for gas bremsstrahlung radiation from the storage ring is studied. Gas bremsstrahlung is produced when the stored electron beam interacts...
With the development of radiotherapy,the need for high doses became strong.However, existing ion chambers are either more absorbent of X-rays in terms of material or are non-sealed, that subject to environmental influences and have a short lifecycle. Now we designed a new ion chamber,which have high dose pass-rate,sealed and long lifecycle under radiation environments.The dose pass-rate...
Ultrafast micro-bunched electron beams have broad applications, including wakefield-based acceleration and coherent Terahertz sources, where precise diagnosis of individual bunch-to-bunch spacings is critical. However, high-precision direct measurements of these spacings remain challenging. This paper introduces a novel method capable of measuring these spacings with femtosecond temporal...
In this work, we analyze the movement of the electrons and ions inside a Faraday cup with different biasing of the collector cup, drift tube and suppressor ring. The possible error due to wrong biasing is also investigated. The particle pass is tracked in different biasing configurations. Also, the effect of stray electrons and ions, which are generated due to gas ionization along the beam...
In the high current hadron machine, it is essential to reduce the beam loss along the machine for machine maintenance and safety reasons. The linac of Chinese Spallation Neutron Source (CSNS) delivery negative hydrogen bunches with power of 5kW to the RCS which increase the power to 100 kW. In the following several years, the power of the linac beam will be increased to from 5 kW to 100 kW,...
Monitoring the beam length and maintaining stability during operation is crucial for Free Electron Laser (FEL) user facilities. A monitor based on Coherent Synchrotron Radiation (CSR) is an ideal candidate, and it has been successfully developed at the Shanghai X-ray Free Electron Laser (SXFEL). This article presents the basic principles, system configuration, and experimental results. The...
The Siberian Ring Photon Source (SKIF) is a fourth-generation synchrotron light source that operates at a beam energy of 3 GeV. In order to ensure the reliable operation of the accelerator, a beam loss diagnostics system will be implemented. For the linear accelerator, linac-to-booster and booster-to-storage ring transfer lines, fiber-based Cherenkov beam loss sensors will be used. Multi-mode...
Chinese Academy of Engineering Physics terahertz free electron laser facility (CTFEL) is a superconducting linac-based user facility. It provides laser pulses with frequencies from 0.1 THz to 4.2 THz. CTFEL works in pulsed mode with a repetition of 10 Hz where up to about 54000 bunches at a bunch spacing of 18.5 ns are accelerated in one macro-pulse. To satisfy the high-precision...
This paper describes the optical beam diagnostics available at the BESSY II booster synchrotron.
For the first time, diagnostics are established to investigate the distribution of the electron beam in all three dimension.
A permanent installation of a source-point imaging system aided by a telescope optic depicts the transverse properties of the electron beam.
Additionally, the bunch...
CERN H- Linac 4 (L4) and ion Linac 3 (L3) operate with millisecond beam pulses, which pose a challenge for beam current measurements based on Fast Beam Current Transformers (FBCTs). In the past the low cut-off frequencies of the FBCTs were actively lowered using a combination of transimpedance (TI) amplifiers and integrating amplifiers. Unfortunately, in many locations such amplifiers were...
High Energy Photon Source (HEPS) is the fourth-generation light source under construction in China. The electron gun system is the origin of beam acceleration. This article introduces the wide range and high precision grid-cathode modulation of beam current for the HEPS electron gun system. Its grid-bias voltage adjustment is as fine as 0.01V. Cathode filament current and voltage ripple＜0.1%....
