The Iranian Light Source Facility Storage Ring is under design with a 528 m circumference and will store the electron bunches with 3 GeV energy to produce high-flux radiation that ranges from infrared to hard X-rays. Two Striplines are planned to be installed in the ILSF storage ring for beam tune measurement. The first one will be used for exciting the beam and the other for horizontal and vertical beam position measurements. In this paper, the design of the striplines for the ILSF storage ring is investigated. Each stripline is matched with 50Ω and has 4 strips (electrodes) that are placed at 45 degrees to the beam axis, the best geometry is achieved and optimized by CST Microwave Studio simulation.

The Iranian Light Source Facility Booster is under design with a 504 m circumference and will accelerate the electron bunches from 150 MeV to 3 GeV. the 50 button-type beam position monitors (BPMs) are considered the non-destructive tools to measure the beam position in the ILSF booster. In this paper, the design of the BPM for the ILSF booster is studied. The BPM blocks have 4 buttons (electrodes) that are placed at 45 degrees to the beam axis. to choose the best geometry, The BPMs with different button diameters and gaps are simulated by the CST Microwave Studio and BpmLab.

The injection kicker design exploiting strip-lines and linear taper connections of the strip-lines to the feedthroughs was proposed and has been successfully used in the DAFNE electron-positron collider [1]. Such a design has helped to reduce the device beam coupling impedance, to improve the uniformity of the deflecting electromagnetic fields and to provide better matching with the feedthroughs. In this paper we propose using nonlinear taper connections in order to decrease further the beam coupling impedance. We have performed numerical simulations and analytical studies of several nonlinear tapers demonstrating that the coupling impedance can be substantially reduced while keeping or even improving the transfer (signal) impedance of the strip-line kickers (or BPM). The effect of the nonlinear tapering is particularly important for short strip-line devices when the taper length is limited due to lack of available space and/or when the strip-lines are moved closer to the beam in order to increase the device shunt (signal) impedance.

Wuhan Photon Source (WHPS), as a fourth-generation synchronous light source, imposes stringent requirements on the resolution and longitudinal coupling impedance of the Beam Position Monitor (BPM). To address the need for beam current monitoring in its 1.5 GeV diffraction-limited storage ring, an optimized design scheme for button BPM is proposed. Additionally, the structure of the BPM feedthrough is enhanced, and a detailed investiga-tion into the impact of various materials on the longitudi-nal coupling impedance of the BPM is conducted. These findings serve as a valuable reference for the future de-sign of similar BPM systems.

The CSNS accelerator complex is upgrading the injection area to improve the beam-loss control during beam injection and acceleration in the Rapid Cycling Synchrotron. At CSNS, the linac beam energy will be increased from 80MeV to 300MeV employing a new superconducting accelerating section, and the beam power at the spallation target will be 500kW. To accomplish these requirements, a stripline-type BPM has been designed with a large aperture and 50 Ω stripline electrodes. This BPM has an inner diameter of 52 mm and is used to detect the beam with a current of 10-30 mA and a pulse width of 100-500us. Several geometrical and electrical parameters have been optimized with numerical simulation. This paper will describe the design and optimization of the stripline-type BPM in detail, and simulation results are discussed.

This study conducted offline calibration tests on the stripline Beam Position Monitor (BPM) designed for the Hefei Advanced Light Facility (HALF) injector. The Lambertson method was used to measure the off-set between the electrical center and the mechanical center of the BPM, with results showing horizontal and vertical offsets of 0.1154 mm and 0.1661 mm, respec-tively. Additionally, the wire-scan method was em-ployed to construct the BPM mapping, and polynomial fitting was applied to effectively reduce the BPM’s nonlinearity and system errors. The experimental re-sults provide essential data support for the optimiza-tion and practical application of the BPM in the HALF injector.

The Korean 4GSR project is currently under construction in Ochang, South Korea, with the aim of achieving first beam commissioning in 2027. Designed to achieve an emittance approximately 100 times smaller than that of third-generation synchrotron radiation storage rings, the project requires the development of several high-precision beam diagnostic devices. In particular, the beam position monitor (BPM) is aimed at reducing longitudinal wake impedance to suppress heating and beam instability. For this purpose, two types of 4GSR BPM pick-up antennas have been developed. The first utilizes a SiO2 glass insulator, while the second is designed in a cone shape using Al2O3. The differences and advantages of the two designs are explained, and the performance obtained through actual beam tests will be described. This presentation will provide an overview of the current development status of the beam position monitor developed for the 4GSR project, including details on the approximate configuration of the 4GSR BPM system.

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.

Beam Position Monitors (BPMs) are essential in parti-cle accelerators for the precise measurement of beam trajectories. Considering the inherent inaccuracies in manufacturing and assembly, rigorous offline calibration processes are essential to guarantee the precision of beam position measurements. The predominant calibration technique, specifically the wire test method, is tailored for relativistic beams and is inappropriate for low-β beams. This manuscript introduces an innovative ap-proach employing a helical slow-wave structure to emu-late the electromagnetic fields of low-energy beams, thus facilitating the calibration of BPMs for low-β scenarios. Employing a helix-based calibration platform, we con-ducted the calibration of the nonlinear response of BPMs at the Xi'an Proton Application Facility for a 7 MeV pro-ton beam, with results aligning with the simulation. This advancement expands the precision and range of beam position measurements, substantially enhancing the op-eration and optimization of particle accelerators.

SOLEIL II is the low emittance upgrade project for Synchrotron SOLEIL, targeting an emittance of ~80 pm.rad. The new lattice includes 180 Beam Position Monitors (BPM). Due to the different constraints on the magnet yokes, beam stay clear and synchrotron radiation, 3 different types of BPM will be installed on the storage ring with inner diameter distributed between 16 and 24 mm. Electromagnetic and thermal simulations have been conducted to validate the designs. Manufacturing the feedthroughs is a challenge due to the conical shape of the button and the small (200 µm) thickness of the gap with the BPM body. Prototypes of the button have been made by two different manufacturers, and possibilities for improvement identified. These prototypes will test in the current machine to validate the simulation results. This paper presents the designs, summarizes the results of the simulations, and describes the metrology process and results of the two batches of feedthroughs.

Beam Position Monitors (BPM) are the non-destructive monitors used most frequently at nearly all linacs, cyclotrons, and synchrotrons. The most basic function of BPM is to provide the accurate position of the centre of mass of the beam for closed orbit feedback and other demands. However, due to the error of actual processing, the k value and the actual electric center will be different with the ideal k value and electric center of BPM, which requires us to accurately measure the k value and offset value of each set of BPM offline. There are 72 sets of BPMs in HIAF BRing & SRing, with 10 specifications and plate radius ranging from 180mm to 330mm, but the shape and size of the front and back pipes connected to bpms are variety during actual installation. Based on theoretical analysis, the k value and offset value of the BPM which electrode plates are too close to the flange are greatly affected by the pipes connected to bpm at both ends, and the measurement error can even reach 9mm. Therefore, this paper takes HIAF BRing and SRing BPM calibration as examples to explain how to accurately calibrate BPM.

Obtaining the complete distribution of a beam in high-dimensional phase space is crucial for predicting and controlling beam evolution. Based on the theory of maximum entropy tomography, we developed an algorithm for reconstructing the four-dimensional (4D) transverse phase space distribution. Our algorithm can take any number of 2D linear projections as constraints, and iteratively converges to the unique numerical solution which is the maximum-entropy distribution satisfying the constraints. Having verified the algorithm with simulation experiments, we plan to use it to conduct 4D phase space tomography in the MEBT and HEBT of the heavy ion linac CAFe II.

As many other light sources, ALBA is also going through an upgrade phase leading to ALBA II. In this context, new Beam Position Monitors (BPMs) have to be designed to fit the reduced vacuum chamber. The buttons and the block were designed to be as compact as possible minimizing the impedance to avoid overheat and maintaining a good signal level. Different shapes and materials were simulated and the best were selected to be produced as prototype. In this proceeding, we present the design process and the simulations that lead to the ALBA II BPM button design.

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 Insertion Device (ID) photon beam of a synchrotron can be contaminated with radiation from upstream and downstream bending magnets, causing position measurement errors in blade-type monitors. Beamlines of the low emittance storage ring are particularly sensitive to photon beam position variations, requiring more accurate measurements. To address this, we designed an ionization profile monitor to non-destructively measure the profile and position of the white undulator beam at Korea-4GSR without contamination. Leveraging the relatively large active area of readout devices suitable for small emittance beams we have designed a 1:1 mapping field to defocus photo-ions. Given that the defocusing field can induce errors due to vertical position, we propose a calibration method and validate it using particle tracking simulation.

Quantifying the difference between two beam distributions in high-dimensional phase space is crucial for interpreting experimental or simulation results. This study aims to analyze and compare several common statistical divergences that quantify the differences in high-dimensional distributions, and to determine which of them are suitable for beam physics applications. We tested these divergences with common kinds of initial distributions by computing how the difference values vary when the mismatch factor and emittance change, between the same and different kinds of distributions. These results, along with similar comparisons after extended beam transport, provided guidance on the use and choice of statistical divergences for beam phase space distributions.

The SIRIUS Fast Orbit Feedback system was put into routine operation for users in 2022. New system identification experiments were conducted to develop an accurate black box MIMO model of the feedback loop. The high frequency response discrepancies among several fast corrector magnets are captured in this model and allow prediction of closed loop behavior, which is especially important for designing high gain controllers. This paper describes the obtained model, its validity and enabled improvements on the feedback loop performance and robustness.

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.

The Siberian Ring Radiation Source (SKIF) is an upcoming 4th-generation SR source under construction in Novosibirsk, Russia. The designed beam emittance for SKIF is 75 pm-rad, which corresponds to a beam size of 6 micrometers at the observation point within the dipole magnet. The transverse beam dimensions are essential parameters for tuning and reliable operation of the facility. The SKIF diagnostic suite includes a double-slit interferometer operating in the ultraviolet region of the spectrum. This device's spatial resolution should be sufficient to measure the radial size of the beam to an accuracy of 10 percent. These diagnostics will be used during the commissioning of SKIF and afterwards. Although an additional source of information on beam dimensions and dynamics would be desirable for assurance, taking into account the record designed value of beam emittance. The application of X-ray optics and the Kirkpatrick-Baez focusing system seem to be the most suitable options. The article discusses the project of this system, which will acquire X-rays from a SKIF dipole magnet. Simulations of the heat load on the mirrors, means of compensation of thermo-induced surface distortion (thermo-bump) and the spatial resolution of the KB system are described. The choice of scintillator screens, expected temporal resolution, and sensitivity of the diagnostics are discussed as well.

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.

A Long Radial Probe is a device used to measure the transverse beam profile in a cyclotron along its radius. The current iteration of the probe was installed in the PSI Main Ring Cyclotron in 2022. After a successful start, the probe encountered issues due to strong coupling with RF fields leaking from the cavities, which resulted in the breakage of the carbon fibers. A series of corrective measures were attempted, but the initial results were inconclusive. This paper discusses the challenges faced and presents the experiments and thermal calculations that provided insights into the RF heating issue.

The China Spallation Neutron Source Rapid Cycling Synchrotron (CSNS-RCS) is the first high-intensity pulsed proton accelerator in China and the fourth in the world. The space charge effect is a key factor limiting power enhancement. Measuring the frequency shift induced by the space charge effect is an important method for studying this phenomenon. In our experiments, we varied the beam current by adjusting the injection pulse length and chopping rate. Using a combination of narrow-band filtering and Fast Fourier Transform (FFT) techniques, we successfully observed a tune shift of approximately 0.02 induced by a beam power of 140 kW. These experimental results were compared with simulation outcomes, showing good agreement.

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 sensitive to interference from neighbouring power systems. The situation was particularly difficult in L3, where in addition to long beam pulses, the challenge was also small beam currents. The interference problems had been addressed for years with limited success and finally it was decided that the whole FBCT front-end electronics should be renovated, with the main objective being to improve the immunity to interference. This paper describes the evolution of the FBCT front-end electronics and installations, which has finally allowed reliable beam current measurements, whose examples are provided. The key improvement was the use of small TI amplifiers directly connected to the FBCTs, which in addition simplified installations in both linacs. The TI amplifiers provide an active low impedance load to the FBCTs, extending their time constants by some two orders of magnitude, as compared to operation with a 50 Ohm load. Challenges of the TI amplifier implementation are described, along with particularities of their beam commissioning.

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 distribution and achieve a decrease in operating frequency has become a research topic of significant importance. In current cyclotron-based proton therapy devices, challenges arise from low beam repetition rates and weak intensities. These characteristics make traditional cavity beam diagnostics ineffective, resulting in monitoring blind spots during treatment. To tackle this challenge, this paper introduces a metamaterial-loaded cavity beam current monitor (BCM). Electromagnetic simulations reveal that this approach significantly reduces the size of the cavity under low-frequency operational settings. Moreover, this technique addresses the problem of high energy loss observed in conventional dielectric-loaded cavity BCM, effectively improving sensitivity. The all-metal metamaterial structure also circumvents difficulties associated with processing. This innovative design presents a fresh avenue for exploring the development of compact cavity beam diagnostics suitable for low-frequency operational environments.

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 the phase reaches 0.2ps, and the measurement accuracy of the beam length reaches 1ps. At the same time, we develop a single beam tracking software based on the mbtrack2 software package. The simulation software can record the phase space evolution of the beam after injection under different initial conditions. By matching with the simulation results, we can get various initial parameters of the experimental beam, including the initial phase, the initial beam length, the initial energy deviation, the initial energy dispersion, and the initial injection angle of the beam in the phase space. This technology enables us to understand the kinetic behavior of the particle beam deeply and to monitor and adjust the injection system in real-time. By obtaining the phase space distribution information of the particle beam in real-time, we can find and correct the deviation and instability in the injection system in time, so as to improve the injection efficiency and the quality of the particle 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, therefor it is important to deal the beam loss more carefully. In this paper, we present the reconstruction of the beam orbit along the linac using beam tracking software with the input data measured with BPMs. This kind of reconstruction is expected to provide suggestions for the future machine tuning. The requirements for the BPMs are also presented in this paper.

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 direction since both field components are correlated, and the focusing of the magnetic field occurs in the azimuthal direction. In this presentation, we propose an analytical method for finding the centre of a solenoid magnet and present results validated by simulations.

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.