The talk shall present an overview of the FCC beam instrumentation needs, the corresponding main challenges. This will review the different R&D activities being currently pursued, including Beam position and loss monitoring, Transverse and longitudinal monitoring systems as well as polarimetry and luminosity monitoring.

A new infrared free-electron laser FEL facility named FELiChEM has been built at University of Science and Technology of China in Hefei. It is a user facility dedicated for energy chemistry research and can deliver the infrared laser in the spectral range of 2.5-200 μm to five research stations. FELiChEM consists of mid-infrared MIR and far-infrared FIR free-electron laser oscillators driven by a 60 MeV linac. The time structure of the electron beam can be easily tuned with the macrobunch width of less than 10 μs macrobunch repetition rate of 1--10 Hz and optional microbunch repetition rate within 238, 119, 59.5 and 29.75 MHz. A 3D bunch-by-bunch position measurement system was developed to monitor not just the average position of the macrobunch but also every individual bunch position in the train. With this toolkits, a significant beam loading effect can be easily observed downstream of the linear accelerator structure, and a strong dispersion effect is observable downstream of the optical oscillator. This diagnostic tool proves to be very useful for analyzing the status of the machine and implementing corresponding optimization measures. This paper will give a brief introduce of the machine, the hardware and software structure of the 3D position measurement system, and its application in machine commissioning and operation.

A new 1mA ion source and a new injection line are presently under construction at TRIUMF for the 500 MeV H- cyclotron. A 300keV ion beam is pulse modulated at the exit of the ion source with a duty cycle varying in the range 1% - 99%. The pulse repetition frequency is around 1kHz and this is the only time varying beam structure available for a substantial fraction of the injection line, till the beam is bunched with an RF-frequency of 23MHz, before being injected to the cyclotron. A set of new diagnostics was developed to support operation of the injection line including the beam position monitoring system operating in the kHz regime. The beam position measurements are based on capacitive pickups and high-impedance electronics to extend the sensitivity towards low frequencies. Details of the system and test measurements will be presented.

The common beamline of the AWAKE experiment at CERN involves the co-propagation of two particle beams: protons with 48 nC bunch charge and 250 ps bunch length, and electrons with up to 600 pC bunch charge and approximately 4 ps bunch length. The existing operational beam position monitors at AWAKE cannot measure the electron bunches whilst the more-intense proton bunches are present, due to their low operating frequency. In order to try to address this challenge, two different types of high-frequency pick-ups were studied, a conical-shaped button pick-up and a Cherenkov diffraction radiation-based pick-up designed to operate at around 30 GHz. Both devices were installed at AWAKE and were connected to two identical read-out systems designed by TRIUMF. This contribution presents and discusses the results obtained from beam-based measurements during the current experimental year.

The construction of China Accelerator Facility for Superheavy Elements(CAFe2) is advancing based on Chinese ADS Front-end Demo Linac(CAFe). However, the original Beam Position Monitor(BPM) read-out electronics of CAFe could not meet the requirements of the CAFe2 BPM probes in terms of quantity and the measurement demands of low-intensity heavy ion beams. In response to this challenge, a high-speed RF switch array supporting multi-channel multiplexing, adjustable gain and filtering was developed. This array served as the RF signal conditioning front-end, together with the RF front-end and digital signal processing platform, to constitute a complete BPM read-out electronics. Laboratory testing validated the feasibility of the high-speed RF switch array and the entire read-out electronics. Compared with traditional read-out electronics, the read-out electronics equipped with the high-speed RF switch array enables the measurement of 32 signals from 8 BPM probes. This approach significantly improves the system's integration and reusability, while offers an efficient solution for implementing multi-channel time-division multiplexing measurement under different beam intensities and operating frequencies. Additionally, by simultaneously accessing signals from multiple BPM probes, this system better supports differential measurement. Overall, the high-speed RF switch array not only meets the requirements of CAFe2 but is also applicable for other accelerators with multiple BPM probes.

This paper presents a prototype of BPM electronics for experimental installation of free electron laser and high magnetic field (FEL-HMF). FEL-HMF integrates mid-long Infrared free electron laser, high magnetic field and cryogenic, which is a critical apparatus for new advanced materials especially for low-power electronic materials. The BPM electronics consists of two ADC chips and one FPGA SoC. The ADC has two channels, and sampling rate is 240Msps. The FPGA SoC implements high speed digital signal and data process. The logic part of FPGA SoC is running signal process. The processor part of FPGA SoC runs Linux operating system and EPICS-based user application program. This BPM electrons has been tested and analyzed in lab. Its X and Y position is ~1.4um (RMS).

Hefei Advanced Light Facility (HALF) is a fourth-generation vacuum ultraviolet and X-ray diffraction limit synchrotron radiation (DLSR) light source under construction. It is expected to have an ultra-low emittance and an extremely small beam size, which requires high-precision orbit detection and fast feedback control. The processor is the key component of the digital beam position monitor (DBPM) and control system, which is required to provide a submicrometer resolution in beam position measurement with a processing latency of lower than 90 μs. This paper presents the design and testing of a high-precision low-latency DBPM processor. In order to reduce the latency and ensure the high position resolution, a specific higher sampling frequency is chosen to reduce the quantization noise platform of the analog to digital convertor and an optimized low-order filter is adopted. Specialized efforts are devoted to the low jitter sampling clock generation and low noise analog circuit design. Furthermore, a dual-pilot tone structure was employed to compensate the gain variations across the four channels of the beam monitor sensor. The laboratory test results show that the DBPM has a position resolution of better than 400 nm for turn-by-turn acquisition, better than 90 nm for fast acquisition at 20 kHz rate, and better than 20 nm for slow acquisition at 10 Hz rate, with a total latency of less than 80 μs.

We are developing a BPM system for the 6 GeV fourth-generation light source, SPring-8-II, which is a renewal of the third-generation light source, SPring-8. The new storage ring will be equipped with 340 button-type BPMs. BPM heads with molybdenum button electrodes have been designed to achieve the position sensitivity coefficients required for SPring-8-II as well as minimal beam impedance and heat dissipation. The BPM heads for the vacuum chambers of the prototype cell are currently being fabricated to validate the mechanical design. As for radiation-resistant signal cables, PEEK-insulated semi-rigid cables will be used for connection to the BPM head, and polyethylene-insulated corrugated cables relay from the girder side to the readout electronics. High-precision and stable readout electronics consist of RF front-end boards and high-speed digitizer boards based on the MTCA.4 standard. The initial batch of electronics has already been installed to replace the obsolete single-pass BPM system of the current SPring-8, and the performance evaluation is in progress. In this presentation, we will report the overview and the development status of the SPring-8-II BPM system.

The Cavity Beam Position Monitor (CBPM) system at Accelerator Test Facil- ity 2 (ATF2, KEK, Japan) operates with attenuation at a reduced 200 nm (vs measured 20-30 nm) resolution to cope with CBPM to magnet misalignment. In addition, CBPMs need regular calibrations to maintain their performance. To address these limitations, a pulse injection system is under development. This system aims to compensate for static offsets by injecting an anti-phase replica of the average beam signal directly into the sensor cavities. The same signal can provide a calibration tone for the whole processing chain and eliminate lengthy beam-based calibrations. Proof of principle tests for such a system have been conducted in December 2023. In this paper, we report on the results of the first beam test, discuss the technical challenges and provide a preliminary hardware specification for future experiments.

The High Intensity Proton Accelerator (HIPA) at PSI presently has an RF beam position monitor (BPM) system based on 20 year old Xilinx Virtex-2 Pro Systems-on-Chip (SoC), using application-specific integrated circuits (ASICS) for direct digital downconverters. For the planned upgrade of the electronics as well as for new HIPA projects, we started the development of a new HIPA BPM electronics, using a generic electronics platform called "DBPM3" that is already being used for SwissFEL and SLS 2.0 electron BPM systems. In this contribution, first test results of a DBPM3-based HIPA BPM electronics prototype are presented, including a comparison with the present electronics.

The AWAKE facility uses novel proton beam-driven plasma wakefields to accelerate electron bunches over 10m of Rubidium plasma. Precise monitoring of 2 diverse beam types necessitates an electron beam position monitor (BPM) working in a frequency regime of tens of GHz. A high frequency conical button-style BPM with a working regime of up to 40 GHz has been investigated as a way to discriminate the electromagnetic fields of 19 MeV, 4 ps electron bunches propagating spatially and temporally together with a 400 GeV, 170 ps proton bunch in the AWAKE common beamline. The sensitivity of the HF BPM to the electron beam position is determined under various beam conditions, with both electrons and protons, and integration with a TRIUMF front-end is discussed.

Beam position monitor(BPM) is used to measure the horizontal and vertical positions of the beam in the vacuum pip.　Before online installation,　it usually needs to be calibration.　High Intensity Heavy-ion Accelerator Facility(HIAF) and China initiative Accelerator Driven System(CiADS) will need a large number of BPM,　so it is a great challenge for BPM calibration work. In order to complete this work efficiently and accurately,　this research designs and develops an automatic BPM calibration system. The hardware of this BPM calibration system consists of 4 major sections,　they are calibration platform equipment, precise motion control device,　signal processing electronics and industrial computer. The control software was programmed by C to realize automatic calibration functions based on EPICS. A high-order fitting algorithm programmed by python used to solve the problem of smaller linear range of the capacitive BPM. It significantly improves the accuracy of position measurement after calibration.

High Energy Photon Source (HEPS) is a proposed new generation light source with a beam energy of 6 GeV, high brightness, and ultra-low beam emittance. An RF BPM has been designed at IHEP as part of an R&D program to meet the requirements of both the injection system and storage ring. The RF BPM architecture consists of an Analog Front-End (AFE) board and a Digital Front-End board (DFE) based on a custom platform. In this paper, we present the overall architecture of the RF BPM electronics system and the performance evaluation of the BPM processor, including beam current, filling pattern, and position measurement resolution as a function of the beam current.

The first phase of the China Spallation Neutron Source (CSNS) project aims to accelerate negative hydrogen ions to 80 MeV using a linear accelerator. Subsequently, these negative hydrogen ions are converted into protons after stripping, and then injected into a rapid cycling proton synchrotron. The proton beam is further accelerated to an energy of 1.6 GeV and guided through a beam transport line to a tungsten target, where spallation reactions gen-erate neutrons. With the initiation of the Phase II project of the China Spallation Neutron Source (CSNS II), the target power is anticipated to increase significantly to 500 kW in the future. Upgrading the existing 32 sets of BPM electronics on the Rapid Cycling Synchrotron (RCS) ring is essential to accommodate the enhanced beam power and fulfill the new requirements of the beam measurement. This paper focuses on the novel design and validation of the BPM electronics, as well as the execu-tion of tests during beam operation.

A BPM signal processor has been developed for SSRF since 2009. It composed of Virtex5 FPGA, ARM board, and 4 125MSPS sampling rate ADCs. Since then, electronic technology has made significant progress. Such as Zynq UltraScale+ MPSoC FPGA contains both hard-core ARM and high-performance FPGA, and ADCs with a sampling rate of 1GSPS have been applied in mass production. A new BPM processor with Zynq UltraScale+ MPSoC FPGA and 1GSPS ADCs is under development at SSRF. Due to the application of new technologies, the processor performance will be significantly improved. The new processor can also meet the needs of ultra-low emittance measurement for the new generation of light sources. This paper will introduce the design of the processor and the relative tests.

This paper presents the first experiences acquired with the new eBPM system based on pilot tone compensation, developed for Elettra 2.0. After the successful delivery of seven complete systems, belonging to a pre-series production within the signed partnership with Instrumentation Technologies, we started their integration in the current machine, in order to gain experience and develop all the functionalities required for the future commissioning of the new accelerator, scheduled for 2026. To do so, an entire section of Elettra storage ring has been equipped with the new systems: eight Libera Electron units have been replaced by eight Pilot Tone Front End (PTFE) and four digital platforms (DAQ10SX). Tests were carried out during dedicated machine shifts, focusing on integration with the new global orbit feedback at different data rates (10 kHz, 100 kHz and turn-by-turn), with and without pilot tone compensation. Nevertheless, triggered acquisitions were made in order to test first turn capability of the system. Another unit has been attached to a pair of spare pick-ups (low-gap BPMs), in order to continue the development of new features and to provide different types of data (raw ADC data, turn-by-turn calculated positions, etc.) for machine physics studies, even during user-dedicated shifts.

This paper will show beam position studies performed using a Cherenkov Diffraction Radiation (ChDR) based Beam Position Monitor (BPM) at Diamond Light Source (DLS). Displaying the characterisation of the BPM using the 3 GeV electron beam at DLS and comparing the effectiveness of this prototype to an existing Inductive Beam Position Monitor (IBPM) in use in the DLS Booster To Storage (BTS) transfer line. The functionality of the BPM is explored, utilising both wideband and narrowband ChDR emission with the application of filters to the ChDR detection system.

In this paper we are presenting the status of the partnership between Instrumentation Technologies and Elettra Sincrotrone Trieste for the realization of 200 BPM electronics for ELETTRA 2.0. Last year, 200 Pilot Tone Front-End (PTFE) units were successfully developed and produced. During the present year, 100 Digital Acquisition platforms, each one used to digitize and process the signals from two BPM pickups, are in production after the successful pre-series tests. Elettra Sincrotrone Trieste was more involved in concept design, prototype development, and firmware programming, while Instrumentation Technologies was focused on design for manufacturing, implemented rigorous testing procedures, and handled the production. During the project, it was also necessary to overcome a period of material shortages, particularly for the chips used in the digital part. Testing during the pre-series and series production phases ensured that each unit met the desired performance criteria necessary for stabilizing long-term measurement drifts in BPM systems. Additional units were produced to account for potential failures and performance variations, ensuring that all units delivered performed to specification.

MYRRHA (Multi-Purpose Hybrid Research Reactor for High-Tech Applications) aims to demonstrate the feasibility of high-level nuclear waste transmutation at industrial scale. MYRRHA Facility aims to accelerate 4 mA proton beam up to 600 MeV. Beam Position monitors are key elements in many accelerators. for instance, once BPMs are installed along a linear accelerator or a storage ring, they remain inaccessible for any validation of updated or rejuvenated electronics. this paper addresses this issue with the realisation of an electronic test bench simulating the outputs signals of BPM electrodes for a given beam energy, phase and position. the bench is realized for MYRRHA BPMs and it offers simulated beams with a position precision down to 50μm and phase precision down to 0.5° on a wide range.

MYRRHA (Multi-Purpose Hybrid Research Reactor for High-Tech Applications) aims to demonstrate the feasibility of high-level nuclear waste transmutation at industrial scale. MYRRHA Facility aims to accelerate 4 mA proton beam up to 600 MeV. The accurate tuning of LINAC is essential for the operation of MYRRHA and requires measurement of the beam transverse position and shape, the phase of the beam with respect to the radiofrequency voltage with the help of Beam Position Monitor (BPM) system. MYRRHA is divided in two phases, the first phase, called MINERVA, includes several sections allowing beam acceleration up to 100 MeV. the second phase includes a High Energy Beam Transport (HEBT) line up to 600MeV. A BPM prototype was realized for the HEBT line. This paper addresses the design, realization, and calibration of this BPMs and its associated electronics. The characterization of the beam shape is performed by means of a test bench allowing a position mapping with a resolution of 0.02 mm.

Measuring the absolute position of the beam in the intensifier and storage ring of a high energy photon source (HEPS) requires measuring the offset between the electrical and mechanical centers of the beam position monitor (BPM). In the HEPS project, a four-electrode BPM is used, and the signals from each of the four electrodes of the BPM probe are led out by a cable. During the operation of the intensifier and storage ring, the influence of ambient temperature and humidity on the BPM cable and the difference between the four channels will directly lead to changes in the BPM measurement results. In this paper, vector network analyzer (VNA) is used to test the data of signal amplitude change of two BPM cables within ten hours when temperature and humidity change. The conclusion is that the influence of temperature on the signal is about 0.01 dB/℃, the influence of humidity on the signal is about 0.05 dB/10%, and the relative change between channels is about 5%.

The classical double-aperture interferometry using the visible part of the synchrotron radiation has been used in accelerators for beamsize measurements since the late 90s. However, this technique provides the beam size projection only in the direction given by the two aperture centers (i.e. only the horizontal or vertical direction). To fully characterize the transverse electron beam ellipse, given by the two semi-axis of the ellipse and its tilt angle, the double-aperture system could be rotated in a process that can take few minutes. Instead, using radio-astronomy techniques, this paper shows a new interferometric method with several apertures by which a full 2d transverse beam characterization is done in real-time.

Several experiments were done to measure the transverse beam size at the NCD ALBA beamline using the Heterodyne Near Field Speckles (HNFS) technique. Inside the FCC collaboration, it was decided to move these experiments to the ALBA Front End 21, where currently an x-ray pinhole camera is working since 2021. The goal is that the two measurement techniques can work alternatively and measure the electron beamsize of the same source point, so that a direct comparison between both techniques can be done. This paper reports the SRW simulations performed in order to investigate the feasibility of the HNFS experiments at this new location. In particular, it focuses on the effect of the dipole radiation and the design of the high energy and high bandwidth monochromator requirements.

The feasibility of X-ray Fresnel diffractometry to measure small beam sizes beyond the resolution of X-ray pinhole cameras is studied for the case of Diamond Light Source. After the Diamond-II upgrade, beam sizes as small as 4 µm are anticipated and are not resolvable by the X-ray pinhole cameras, which are the workhorse for beam size, emittance, and energy spread measurements. X-ray Fresnel diffractometry employs a single slit with an optimised width, producing a double lobe diffraction pattern. The visibility of this double lobe intensity distribution relates to the beam size and promises micron-scale beam size measurement. Numerical studies and simulations have been conducted to assess the feasibility of diffractometry for Diamond Light Source. The parameters for the experimental setup have been determined and preliminary experimental results are presented. Challenges and improvements for achieving this measurement for Diamond-II are discussed.

SKIF is a synchrotron radiation facility under construction in Novosibirsk. Electron beam energy 3 GeV, beam current up to 0.4 A and extremely low horizontal beam emittance 75 pm$\cdot$rad are convenient to make a high-energy photon source at the main storage ring. Gamma-photons are obtained using Compton backscattering (inverse Compton scattering) of IR, UV and visible laser radiation. Using modern high-power lasers, Compton photons in hundreds-MeV energy range and rates up to 300 MHz can be achieved. Also, higher Compton photon energies (up to 2.6 GeV) can be generated using synchrotron radiation reflected towards the electron beam. A preferable option for photon monochromatisation is tagging photons by recoil electrons with resolution of 0.6%$\dots$0.8% (or $\sim$2 MeV), which is an advantage of ulta-low electron emittance. The discussed Compton source is mainly usable for photonuclear and photohadron processes such as photofission and production of $\pi$, $\eta$, $\Delta$ at nuclei. Also nonlinear QED, EM detectors calibration and other applications are in interest.

For future continuous wave (CW) and high-duty-cycle operation of the European XFEL, research and development of the DESY L-band CW photoinjector is ongoing. The implementation of a superconducting radio frequency (SRF) gun operated at 1.3 GHz with a copper photocathode is the baseline option. The electron beam quality, in particular the slice emittance, produced by this injector is key for the successful operation of the free-electron laser. In order to study the beam quality and stability of operation, a dedicated test stand and diagnostics beamline is being developed at DESY. Here, we present an overview of the foreseen diagnostic components and methods at the SRF CW photoinjector test stand.

A pepper-pot diagnostic device was developed to accurately and robustly retrieve particle distribution in horizontal and vertical phase spaces by single-shot emittance measurements. Two masks that differ in both composition and manufacturing method were fabricated: one made of phosphor bronze by an optical lithography process and another made of stainless steel (SUS) by laser cutting. Scanning electron microscope (SEM) measurements of the two masks revealed that the former is superior in terms of regularity and shape of the mask holes and is therefore more suitable to use. A new image-processing algorithm, cluster noise removal method, was developed which improves the resolution of the phase-space distribution measurements over traditional methods. The results show that the diagnostics can robustly and reliably retrieve the four-dimensional (4-D) phase-space distribution of ion beams with a single-shot measurement.

The 60 MeV Proton Radiation Effects Facility (PREF) spent nearly 1 month at the commissioning phase, during which the multi-strip ionization chamber (MIC) at the experimental terminal offered the core parameters, beam spot, scanning area, scanning uniformity, beam flux. However, the projection distribution provided by the MIC loses some information, such as the flux and the uniformity in a selected area less than the scanning area. This paper used a method of two-dimensional reconstruction to provide a 2D uniformity of selected area. Revealing the trace of the pencil beam at a sampling rate of 10 kHz.

An X-Ray pinhole camera beamline has been installed recently at SESAME storage ring as a very beneficial non-destructive tool, used to characterize the electron beam size and behaviour. The design of the beamline is kept as simple as possible with a modification on the copper absorber to provide a sufficient flux of X-ray proper for imaging. The beamline is under operation now and used for the measurement of beam size, emittance, coupling in the ring, and detection of beam instabilities. This paper describes the design details, simulations and measurement results obtained during the beamline com-missioning.

To enhance the performance of the next generation of X-ray free electron lasers (XFEL), it is essential to produce a high quality electron beam with a low emittance, for instance, below 0.2 mm-mrad for a 100 pC bunch charge. In order to demonstrate the fundamental techniques required for future FEL facilities, a C-band photoinjector test facility has been constructed aligning with the Southern Advanced Photon Source (SAPS) pre-research project. An emittancemeter based on the consecutive double-slit-scan concept has been proposed and designed for determining such small emittance. This paper presents the further optimization of the primary parameters of this emittancemeter employing numerical simulations in the presence of the measured motion accuracy and the expected observation resolution.

The Nanogate-38 gated camera with a temporal resolution of 60 nanoseconds was used to measure the transverse beam dimensions in the BEP booster and the VEPP-2000 electron-positron collider. The camera was used in combination with a double-slit interferometer to measure the vertical beam size and with projection optics to construct a transverse beam profile in single-turn mode. Some beam characteristics were measured, such as decoherence time, radiation damping time and fast attenuation time. The purpose of these experiments was to investigate the possibility of using this camera to measure the transverse dimensions of the beam and its emittance, as well as to conduct experiments on accelerator physics at the SKIF synchrotron radiation source.

Beam Gas Ionization monitors have been in operational use in the CERN PS for two years now, and they were installed in the SPS this year. An overview of the operating principal of the instruments is presented, followed by an update on their development. The mechanical design has been simplified and the Timepix3 devices are now mounted individually for easier assembly and maintenance. Reliability and availability have been improved with a new radiation-hard readout, using the GBTx and bPOL12 devices. Performance has been improved with a SoC Back-End making good use of both the FPGA and the Processing System. We have worked to improve the calibration of the instruments, equalization can now be performed in-situ and we have a procedure to calibrate the response between the four detectors. This paper also presents some example results from the instruments and describes our plans for future developments.

The measurement of the longitudinal phase space at the end of FERMI linac is one of the most important characterization of the electron beam properties prior to delivery to the FEL lines. It is performed using an RF-deflecting cavity in conjunction with a dipole to spread the beam in time and energy. The beam transverse distribution is then measure with a multiscreen. The original multiscreen installed in 2009 had a large FOV with a 45deg YAG orientation and 1.5MPx camera. An upgrade has been devised to improve resolution, frame rate and robustness to COTR contamination. The upgrade design is based on a COTR suppressing geometry, a dispersion minimizing incidence angle, a double mirror vacuum optical layout and a Scheimpflug camera geometry. The optical distortion has been characterized by using a precision checkerboard target and automatic Matlab nodes detection. This leads to a transformation matrix that is applied at the image server level to the raw image to remove the trapezoidal distortion. The detector is 8 Mpx 10 Gbit/s CMOS camera fiber coupled to the image sever and capable of full frame 50Hz acquisition.

Accurate measurement of flux rate is essential in heavy-ion single event effects tests, but it presents significant challenges for monitoring low energy (5~10 MeV/u) and low intensity (less than 1E6 /s) heavy-ion beams. In this paper, we propose a novel detector that enables real-time monitoring of flux rate by simultaneously measuring the beam intensity and profile using secondary electrons on both the front and back surfaces of thin foils. The confinement of sec-ondary electrons through electric and magnetic fields is achieved, with CST simulation has been utilized to validate the method. This approach offers several ad-vantages over conventional methods, including high space and time resolution, reduced mass thickness, and multi-parameter measurement capability.

Although there is no clear definition of beam halo in particle accelerators, it is generally regarded as particles outside of the beam core with an intensity level of less than 10-5 or 10-6 of the peaks. In high-intensity, high-power hadron accelerators, the presence of halo particles may cause emittance growth and beam loss, difficulties in beam control and collimation, increase the noise of detectors, and cause activation or even damage to accelerator components. To understand the halo dynamics, experimental studies are essential, but the required detection techniques are often too limited and do not meet the required high dynamic range. In this contribution, a supersonic gas curtain-based profile monitor is considered for beam halo measurement in high-intensity, high-power hadron accelerators. This monitor is based on the beam gas curtain (BGC) monitor, successfully used in the Large Hadron Collider. Instead of a broad curtain with uniform density, a new concept with two shorter curtain segments which can be adapted to the shape of the beam core and aim at the halo particles only is applied. The monitor design and operating principle will be presented, and the anticipated integration time, signal intensity and dynamic range will be discussed, as well as opportunities for increasing the sensitivity by incorporating micro-channel plates or the Timepix detector.

In the past year, the wire scanner at SXFEL is upgraded to a new firmware. Unlike the previous version, where a target frame is equipped with tungsten wires in three directions, the new system uses horizontal and vertical independent scanning methods. The beam loss detector adopts plastic scintillator fiber, and the PMT module is also designed with a Raspberry PI for dynamic signal conditioning. The detailed design is described in this paper.

To address non-standard Gaussian beam spot pro-files in injectors, this paper proposes a fitting algo-rithm based on Gaussian, the newly introduced Gener-alized Gaussian Type and Skewed Gaussian Type dis-tributions. These distributions are specifically de-signed to better fit non-Gaussian and asymmetric beam spots by automatically selecting the most suitable model. Validation using beam spot images from the YAG screen after the electron gun in the Hefei Light Source II (HLS-II) injector demonstrates that the Gen-eralized Gaussian Type is effective for fitting sharp or broad profiles, while the Skewed Gaussian Type is well-suited for handling asymmetry. Compared to tra-ditional methods, the proposed algorithm improves fitting accuracy and adaptability, providing a practical solution for complex beam measurement challenges.

To serve the needs of the High Luminosity (HL) LHC, a consolidation of the beam wire scanner has been initiated. The instrument is a crucial tool for measuring the transverse beam profile by moving a thin carbon wire across the beam. It can only withstand a fraction of the LHC's nominal beam intensity but provides a reference to calibrate other instruments that operate non-invasively at higher beam intensities. Since the start of the LHC, the scanners have provided hundreds of thousands of measurements, but the design has technical limitations that need to be addressed to provide the required reliability and performance for the HL runs. The initial consolidation phase involved testing the injector's acquisition and control electronics in the LHC to assess its suitability for the specific beam conditions. As part of this process, we updated the mechatronic and motion controller. Beam test campaign has revealed higher performance w.r.t the existing system and a higher adaptability to varying beam conditions. Simultaneously, we are developing a novel actuator that uses a permanent magnets-based coupling replacing the standard bellows and long arm that limits the performance and induces vibrations. Before testing this new concept with beam, we have developed a calibration bench to evaluate the mechanism’s precision and accuracy of the wire position determination. This contribution presents the 2023 beam and laboratory tests as well as the electromechanical developments.

Sensitive cameras are frequently operated to record low-light processes such as Beam Induced Fluorescence or optical transition radiation for transverse profile determination. We compared four cameras based on different principles: Firstly, we investigated an Image Intensifier equipped with a double MCP (producer ProxiVision); secondly, an electron-multiplied CCD (emCCD Teledyne Princeton Instruments ProEm+:512B); and, thirdly, sCMOS cameras (producer PCO.edge4.2bi and Teledyne Kinetix 22). LEDs generate light pulses within a wavelength range of 385 to 500 nm and a duration of 0.03 to 8 ms to vary the photon flux. Moreover, the spatial resolution is compared. The image intensifier is the most sensitive camera type and provides very low noise; however, the method provides only a limited spatial resolution. The investigated emCCD camera has a comparable sensitivity but provides a better spatial resolution. The sCMOS cameras provide a factor of about 5 to 10 lower sensitivity depending on wavelength. A quantitative comparison of signal-to-noise ratios and statical fluctuations for several wavelengths will be presented.

In recent years, with the development of powerful THz source technologies, THz structures are widely utilized for electron beam manipulation, such as acceleration, deflection, compaction and diagnostics. Taking the bunch length measurement as an example, combining with high field strength and high resonant frequency, the THz structure based deflector could reach femtosecond or even sub-femtosecond resolution. In this paper, a 0.1THz Fabry-Perot resonator based structure will be introduced, which could provide time-dependent deflection for short electron beam to resolve the bunch length with high resolution. By adjusting the relative orientation of the beam direction and the E-field direction of the incident THz source, this structure is also potential for beam acceleration.

Future large high-luminosity electron-positron collid- ers such as Circular Electron Position Collider (CEPC), and Future Circular Collider (FCC-ee) require nanometre-sized beams at the interaction point (IP). The luminosity is very sensitive to the beam orbit drifts at the IP. It is essential to have a fast luminosity feedback system at the IP to maintain optimum beam collision conditions and prevent a luminosity degradation due to orbit drifts in the presence of mechanical vibrations and dynamical imperfections.We considered two possible methods for this purpose for CEPC: one based on measurements of the luminosity and the other based on measurements of the beam orbits around the IP. In this paper, we present the preliminary design consideration for a fast luminosity feedback system at the IP of CEPC.

SOLARIS, a third-generation synchrotron radiation source in Kraków, Poland, is dedicated to providing high-brilliance X-ray beams for various scientific disciplines. The successful operation of a synchrotron radiation facility heavily relies on precise control of the electron beam orbit within the storage ring. Orbit deviations, even on a small scale, can adversely affect beam quality, leading to decreased performance and efficiency of experimental setups. To mitigate these effects, an Orbit Feedback System is essential, providing correction of orbit deviations. In this study, we present the implementation of an enhanced Orbit Feedback System consisting of fast and slow orbit correction systems as well as RF drift compensation. System consists of feedback algorithms calculating corrective actions of the actuators (fast and slow correction magnets) based on beam position measurements. We also present first measurements and tests for the system showing its capabilities.

The commonly used bunch-by-bunch transverse feedback system is based on the scheme of analog down-conversion, which down converts the 3fRF beam signal to the baseband with a phase adjusted local oscillator. The system contains a large number of analog devices, which make the system complex and vulnerable to environment changes. Today, sampling the high frequency signal directly with high performance ADC is available. A new bunch-by- bunch feedback system based on RF direct sampling is under development at SSRF. The new system structure is much simpler compared to the traditional one and much powerful. The direct sampling processor has 4 input channels, which can simultaneously process horizontal, vertical, large bunch vertical feedback, and bunch charge measurement. The RF processor has 4 ADC channels (maximum sampling rate is 2.6GHz, bandwidth is 9GHz), 4 DAC channels (maximum frequency is 500MHz). The processor uses Xilinx system-on-chip UltraScale+ MPSoC FPGA. Paper will introduce the system structure, the processor design and performance, FIR filter designing and preliminary tests.

For the ongoing upgrade of the Swiss Light Source (SLS) storage ring, the previous ageing beam-based feedbacks and beam position monitor (BPM) systems are replaced by newly developed versions, where beam commissioning is planned to start in January 2025. Feedbacks include the fast orbit feedback (FOFB), transverse and longitudinal multibunch feedback (MBFB), and filling pattern feedback (FPFB). In this contribution, we give an overview of the architectures and development/production status of these feedbacks and of the BPM system, including latest pre-beam test results.

The upgrade of the fast orbit feedback (FOFB) system is currently underway at the PF-ring. The new FOFB system consists of MicroTCA-based BPM electronics and a feedback control (FBC) unit. The BPM electronics are prepared with the same number as BPMs and synchronously transmit 10-kHz rate beam position data to the FBC unit via an optical data link. The FBC unit immediately calculates the closed orbit distortion from the received position data and performs an inverse matrix operation to correct it. The results are converted to analog signals by fast D/A converters and set to power supplies of the fast steering magnets. The primary goal of the new FOFB system is to archive a closed-loop bandwidth of 100 Hz, which is about 100 times the current system performance. Details on the new BPM electronics and the new FOFB system using them will be presented as well as some initial results obtained during beam tests.

The Shanghai High repetition rate XFEL and Extreme light facility (SHINE) accelerates electrons to 8GeV with a high repetition rate of up to 1MHz. For the transverse beam profile measurement in the high energy sections wire scanner is used as an essential part of the accelerator diagnostic system, providing the tool to measure small beam size in an almost non-destructive manner. The prototype of the data acquisition and processing platform of wire scanner is designed and installed at the Shanghai soft X-ray Free Electron Laser (SXFEL) for verification. The experimental results show that the platform can be used for the SHINE.

A generic signal processor has been developed for beam diagnostic system in SHINE. The stand-alone processor is used for the signal processing of stripline BPM, cavity BPM, cold button BPM, beam arrival measurement, bunch length measurement and other diagnostic systems. The main core is a SoC FPGA, which contains both quad-core ARM and FPGA on a chip. The ARM runs LINUX OS and EPICS IOC, and FPGA performs peripheral interfaces and high-speed real-time signal processing. An FMC carrier ADC board is mounted, which can sample 4 channels input signal with a maximum sampling rate of 1GSPS. The processor is equipped with a White Rabbit timing card, which can realize 1MHz high repetition rate synchronous measurement. Lab test results and on-line beam tests prove that the processor has high performance. This paper will introduce the processor development and applications on SHINE.

The Beam Loss Monitoring system (BLM) for the HEPS booster ring consists of 27 plastic scintillators and 4 optical fibers. An open source hardware is used in the data acquisition of the Scintillator BLM system, to monitor the beam loss during the injection and energy ramping process. Design details and application is described in this paper and the commissioning results of is also present.

The Iranian Light Source Facility (ILSF) plays a crucial role in advancing accelerator science and applications. In this study, we explore innovative techniques for precise beam profile monitoring, focusing on two complementary methods: Incoherent Cherenkov Diffraction Radiation (ChDR) and scintillating screens. Incoherent ChDR occurs when a charged particle passes through a dielectric medium with a velocity exceeding the phase velocity of light in that medium. This phenomenon leads to the emission of electromagnetic radiation in the form of a cone. Our investigation focuses on incoherent ChDR as a powerful tool for beam position diagnostics. By analyzing the angular distribution of ChDR photons, we extract valuable information about the transverse position of the electron bunch. Our simulations demonstrate the feasibility of ChDR-based diagnostics at ILSF. We discuss optimal radiator materials, geometries, and detection strategies. in addition, We also present our findings on scintillating screen calibration, spatial resolution, and dynamic range. We believe that our research significantly contributes to the development of robust and efficient beam diagnostics at the storage ring of ILSF. By investigating Cherenkov Diffraction Radiation (ChDR) and utilizing radiation from scintillating screens, we enhance accelerator performance and facilitate future experiments.

A superconducting cyclotron-based proton therapy system has been developed at the China Institute of Atomic Energy (CIAE). For the 230MeV proton thera-py cyclotron (CYCIAE-230), the beam profile is cru-cial for the adaptation of the proton therapy planning system and an important basis for the commissioning of the beam line. CIAE designed the scanning wires device for the proton therapy facility, which is for high-resolution profile measurements. A readout elec-tronics unit with fA resolution has been included to adapt to the small signal of scanning wires. The data process unit uses ZYNQ-7035 together with 24-bit ADCs and transmits measurement results via MOD-BUS TCP protocol. The diagnostic electronics are placed close to the beam profile monitors (BPM) to reduce the analogue signal transmission distance. To adapt to the mode of the pulse beam during the beam-line commissioning, using the RF system signal trigger sampling, to prevent the signal aliasing. Besides that, a Butterworth filter and a mean filter were used to filter measurement noise. The design of this scanning wire diagnostic system will be reviewed in this paper, to-gether with several measurement results.

Electronic components in spacecrafts and satellites are subjected to impact of high energy particles and heavy ions. Radiation damage of semiconductor electronic devices depends on linear energy transfer (LET) of the particle in semiconductor material which the device is fabricated of. During radiation testing of electronic components for space applications in particle accelerators we have limited set of ions with fixed energies and LET values due to complexity of adjustment of accelerator systems. According to standard test methods it is necessary to perform tests for several LET values in range from 1 to 100 (MeV*cm^2)/mg. It is possible to e nhance available LET range using special screens with different thickness (degraders) to decrease initial energy of particles and adjust LET value without reset of the accelerator for another ion type or energy. It can significantly reduce complexity and duration of test processing. In this work by numerical calculations we have designed a set of degraders, which enable us to obtain almost any LET value from 1 to 100 (MeV*cm^2)/mg in silicon devices using only four ion types with fixed energies that is acceptable for all test procedures.

This tutorial addresses the realm of electrical, hybrid and specifically optical schemes for achieving a facility-wide synchronisation on the femtosecond level at free-electron lasers (FELs). After a brief introduction to the fundamental principles behind FEL operation and the significance of synchronisation for fully utilising their capabilities. Subsequently, it discusses various methods employed to achieve femtosecond-precision synchronisation, including low-noise timing references, different active stabilisation techniques, and advanced feedback algorithms. In addition, the tutorial provides an overview of the numerous challenges encountered in femtosecond optical synchronisation and solutions developed to overcome them. It discusses technological developments, such as ultra-stable optical lasers or timing diagnostics both for optical pulses and electron beams. Moreover, practical considerations for implementing such systems in FEL facilities are addressed, including stability requirements, scalability, and integration with experimental setups. Results from recent studies highlighting successful synchronisation implementations at prominent FEL facilities are presented.

Photonic time-stretch is a powerful method for recording electro-optic signals with terahertz bandwidth and high repetition rates. The method consist of modulating a chirped laser probe with the signal of interest. Then, the laser pulse is stretched it in time up to several nanoseconds, so that it can be read using an oscilloscope or ADC board. This technique has been shown to be efficient for monitoring the dynamics of Coherent Synchrotron Radiation (CSR) at SOLEIL, and to study electron bunch shape dynamics at KARA. However, the use of this technique has been strongly limited by the need of high bandwidth and costly oscilloscopes required for the readout. We present here a new design that allows a considerable reduction of the required oscilloscope bandwidth. A key point consists of using the 1550 nm wavelength for the probe. We will also present results obtained at SOLEIL, where THz pulses have been recorded, in single-shot and at MHz repetition rates, using an oscilloscope and ADC board with 1 to 3 GHz bandwidth.

Beam energy is a key parameter for free electron laser facilities (FELs). A commonly used nondestructive sys-tem uses a beam position monitor (BPM) to measure the bunch position in a magnetic bunch compressor. At the Shanghai Soft X-ray FEL facility (SXFEL), the chicane stripline beam position method is utilized for this pur-pose. However, this method relies on the initial bunch position before entering the chicane and has a limited linear region. A different non-destructive beam energy system, which measures the bunch flight time using two cavity-based bunch arrival time monitors, has been pro-posed and tested. This paper introduces the development of this system, including design details, build-up, and measurement results. Moreover, it also covers the compar-ison between the two different bunch energy measure-ment methods from several aspects: bunch position-based and bunch flight time-based.

At the Metrology Light Source in Berlin, the concept of Steady-state microbunching (SSMB) is evaluated in a proof-of-principle (PoP) experiment. SSMB has been proposed to deliver kilowatt level average power EUV radiation from an electron storage ring. In the PoP experiment, an energy modulation is impressed onto the electron beam using an infrared laser pulse co-propagating inside an undulator. We show that the beam energy can be measured absolutely by detuning the undulator gap from optimum resonance and observing the intensity of the resulting coherent synchrotron radiation.

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 years. The work of a collaboration of institutes specialized on the various subtopics resulted in a large variety of CCC types with respect to field-pickup, magnetic shielding, SQUID types and SQUID coupling. Many of them have been tested under laboratory and under beamline conditions, which formed a detailed picture of the application possibilities for CCCs in accelerators. In parallel to CCC detector development the cryogenic support system has steadily been optimized, to fulfil the requirement of a standalone liquid helium cryostat, which is nonmagnetic, fit for UHV application, vibration damped, compact and accessible for maintenance and repair. We present the major development steps of the CCC for FAIR. The latest beamtime results are shown as well as recent tests with the cryogenic system. The most promising CCC type for FAIR is the so called Dual-Core CCC (DCCC), which runs two pickups in parallel with independent electronics for noise reduction. The magnetic shielding has an axial meander geometry, which provides superior attenuation of external magnetic noise.

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 singlepass electronics are employed to measure the beam position and phase from the BPMs. Pairs of BPMs were used to measure beam phase shift, which can also be used to calculate beam energy. This paper compares beam phase measurement systematically by BPMs and FCT.

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, and ZYNQ chip was used to process the beam data and calculate the charge of each bunch. This system has been used in HEPS booster and will be used in HEPS storage ring.

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 quartz fibers and photo multiplier tubes (PMTs) will provide spatial resolution for this diagnostic system at a level of about 1 meter. The storage ring will be equipped with 128 scintillation-based detectors with acquisition electronics that are placed around the circumference of the ring. These detectors will be able to measure beam losses both during beam injection and during regular SKIF operations for SR users. Since SKIF will operate in different working modes, the BLMs system will require high sensitivity, a large dynamic range, and sophisticated electronics. The paper describes the design of both types of beam loss monitors (BLMs) and the choice of their positioning around the storage ring. It also discusses the final design of the acquisition electronics, the tests of the BLMs and the current status of diagnostics.

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 development is planned to replace the existing electronics for beam loss signal acquisition. The CSNS-II ring beam loss measurement electronics based on zynq consists of independently developed high-voltage output modules, front-end analog boards, digital boards, as well as related driver programs, epics ioc software,etc,realizing functions such as signal acquisition, range control, data processing, epics publishing.

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 the Machine Protection System (MPS). A customized and robust MPS is designed and developed to give the readiness of the machine for operation, to mitigate and analyze faults related to the relative damage potential. To get a high speed and have a high level of reliability, all interlock signal processing is processed on radiation-tolerant Field-Programmable Gate Arrays (FPGA) with triple or dual redundancy, as well as with a fail-safe design. By implementing a multiprocessing platform system-on-chip FPGA, the HIAF MPS can be tightly integrated with other systems to maximize availability pinpoint failures for operations, and give the postmortem analysis. This paper will describe the architecture of the interlocks linking the protection systems, the strategies to manage the complexity, the detailed components, and the interlock logic of the customized HIAF MPS, as well as the test and verification of the prototype.

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 improves a lot than the latest one ,keeps ultra high vacuum as very low leakage rate and 10 years lifecycle. Another important point is this kind of ion chamber have very simple assembly process and low cost.After our beam test, it performed very well with various test environments as Reproducibility of the dose response, Proportionality of the dose response, Stability of the dose response and so on.

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 principles and composition of these two BLMs, as well as their application in beam commissioning.

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 current measurement module, highlighting key technologies including anti-interference, weak cur-rent detection, multi-channel signal acquisition and processing, and weak current calibration. This module boasts a large dynamic range, high precision, and multi-channel weak current detection, featuring 32 detection channels with a detection range of nA~10μA. Its detection accuracy surpasses 1nA, and its response time is under 5ms. Additionally, the module's design took into account the impact of ionizing and electromagnetic radiation on its performance to ensure its reliability and stability.

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 principle of electron beam deflection, electron beam probe has the potential of multi-function beam diagnosis. Here, we proposed the concept of real-time longitudinal bunch shape monitor with photocathode DC electron gun. Considering the realistic bunch distribution, we investigated the feasibility of this monitor using particle tracking simulation. The results and analysis of feasibility are reported in this paper.

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 years, there has been active work to develop new diagnostics for measuring the parameters of the electron beam in the third stage of the NovoFEL. The laser generates pulses of radiation with picosecond durations in the mid-infrared range of 8-12 micrometers that is the challenge for the diagnostics. This paper describes the development of diagnostic systems for the spectral and temporal characteristics of laser radiation from the third stage of the NovoFEL facility. To record the radiation spectra, a diffraction monochromator was used in conjunction with a bolometric array as a detector. A nonlinear autocorrelator based on ZnGeP2 crystal was developed to measure the temporal profile of the radiation. The correct operation of the autocorrelator was demonstrated in experiments with YAG laser radiation acquired using a nonlinear β-BaB2O4 crystal. The paper presents results from measurements of the spectrum and autocorrelation function for laser radiation from the third stage of the NovoFEL. Self-consistency between the spectrum and autocorrelation functions is demonstrated.

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 setup, bunch length variations caused by instabilities in the acceleration process can be measured that in turn also affects the secondary photon beam. In this paper, we demonstrate the pre-commissioning of broadband, room temperature Schottky THz detectors for the diagnosis of compressed short electron bunches at the TELBE facilities at the Helmholtz-Zentrum Dresden-Rossendorf, Germany. Qualitative bunch compression measurements have been carried out to diagnose the beam to optimize the machine setup and provide feedback to the beam-line scientists for optimum machine operation. These detectors are scheduled to be commissioned at free-electron facilities in near-future.

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 stimulator, a 324MHz RF power source, HV power supplies, a bending magnet and a set of MCP+Screen+camera+DAQ. This paper gives the design consideration, some results of the test bench and the continuing CST design of a λ/2 RF deflector.

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 exceeding 100 watts in the spectral range between THz and mid-infrared wavelengths. Precise measurement of electron beam parameters is crucial for monitoring the performance of the accelerator and fine-tuning its operating modes. The length of the electron bunch is particularly important, as it directly influences the efficiency of laser radiation generation. This study focuses on the dependence of the electron bunch length on the parameters of the radio frequency (RF) and bunching systems for the first and second FELs at NovoFEL. Measurements were conducted using a Cherenkov aerogel radiator in conjunction with a streak camera to accurately determine the electron beam properties. The measurement results, along with a plan for future experiments, are discussed in detail in this publication.

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 length is measured using a streak camera with a resolution in the picosecond range. Both systems can work in parallel and are able to observe the non-equilibrium beam dynamics over the entire booster ramp.

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, particularly in the high-offset frequency range, where jitter remains less than 5 fs from 1 kHz to 1 MHz. Meanwhile, RF master oscillators provide outstanding long-term sta-bility in the offset frequency range. This paper demon-strates that integrating the low-noise performance of passively mode-locked femtosecond laser with the superior stability of RF master oscillator enables the achievement of 10-fs-level synchronization. By im-plementing an RF-based phase-locked loop (PLL) scheme, we achieved an absolute timing jitter of 17.4 fs integrated from 10 Hz to 1 MHz.

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 during KEDR data acquisition runs every 30~minutes with accuracy of 20~keV. In this report the facility design and current status are discussed.

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 these measurements, the system was equipped with several fluorescent screens, Cherenkov radiation detectors, a dipole energy spectrometer, and a Faraday cup. This paper elaborates on the design, mode of operation, and practical applications of these diagnostic devices during the accelerator's tuning process. Further, potential areas of optimization for these diagnostic methods are explored to provide feasible directions for enhancing the performance of the linear accelerator. These precise diagnostic tools have been pivotal in the successful tuning of the SKIF linear accelerator. The results thus gathered will form a significant reference point for the development and refinement of similar accelerators in the future.

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 characteristics, considered one of the critical parameters, need to be precisely measured. Given the high beam energy and the need for a compact, straightforward accelerator layout, we achieved high-precision measurements using only a ordinary dipole, a slit, and a Faraday Cup (FC). This paper presents the online measurement results of beam energy at different cavity voltage and provides a thorough analysis and optimization of the various errors encountered during measurement.

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 this paper we describe a method to measure the H- content utilizing common devices in low energy beam transport line. This method is mainly based on a solenoid. the H- and electron contents can be obtained by analyzing the change of the beam transmission when sweeping the solenoid current. The experiments were performed.

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 energy calibration for BEPCⅡ. In this paper, the preliminary design of this Compton polarimeter is presented, as well as the tentative plan for implementation and commissioning in the coming years are shown.

The Advanced Accelerator Diagnostics collabora-tion has been developing diamond-sensor based high bandwidth position-sensitive diagnostics for applica-tion at next generation XFELs and other accelerator facilities. A pass-through diagnostic with 50 MHz rate capability has demonstrated pulse-by-pulse position sensitivity of 1% of delivered beam width. Progress has been made in upgrading this diagnostic approach to multi-GHz operation, involving an integrated detec-tion system design making use of a compact signal path and proximate high-bandwidth readout ASIC. Preliminary results are presented on the performance of both the signal path and ASIC. Possible additional applications, including precision event timing and plasma ignition diagnosis, are introduced.

Optical Beam Loss Monitors (oBLMs) allow for cost-efficient and spatially continuous measurements of beam losses at accelerator facilities. A standard oBLM consists of several tens of meters of optical fibre aligned parallel to the beamline, coupled to photosensors at either or both ends. Using the timing information from loss signals, the loss positions can be reconstructed. This contribution presents a novel oBLM system recently deployed at the CERN Linear Electron Accelerator for Research (CLEAR). Multiple methods of extracting timing and position information from measured waveforms are investigated, and the potential impact of varying beam parameters such as bunch charge or number is analysed. This work has resulted in the development of a GUI to aid operations by visualizing the beam losses and their positions in real time.