A new X-band mode converter for the Very Compact Inverse Compton Scattering Gamma-ray Source (VIGAS) program in Tsinghua University has been fabricated and conducted low-power testing. S11 is under -30 dB with -0.05 dB of S21 at the operating frequency of 11.424GHz according to the low-power test using the vector network analyzer, which is consistent with simulation results.

The favorable wavelength scaling of ponderomotive interactions indicates that long-wave infrared (LWIR) lasers are well suited for applications such as laser wakefield acceleration and high harmonic generation. CO2 amplifiers are the primary source of such wavelengths, able to generate TW peak powers with sub-ps pulse lengths. However, a limiting factor for these amplifiers is the necessity of using electrical discharges to pump the gain medium, reducing the maximum repetition rate and energy stability. This can be mitigated by instead optically pumping the CO2 at 4.5 μm. We demonstrate a proof of principle of the generation of this wavelength by utilizing stimulated Raman scattering, a process where photons inelastically scatter from a material. For this wavelength, we employ a novel class of material known as ionic liquids as the Raman medium. We demonstrate efficient conversion from a 532 nm frequency doubled Nd:YAG laser to 603 nm in the ionic liquid EMIM DCA, followed by performing difference frequency generation to produce the 4.5 μm pump.

Intra-beam Scattering (IBS) is one of the main mechanisms of emittance blowup and performance deterioration in the Large Hadron Collider (LHC) accelerator complex. It is particularly relevant since the recent upgrades across the injector complex to reach the high brightness beams of the High Luminosity LHC (HL-LHC) era have been implemented. Several studies have focused on developing an accurate formalism to describe IBS, and the integration of IBS in codes such as, e.g. MAD-X, is widely used in the accelerator physics community. This study presents the latest developments of a Python package for IBS simulations, recently developed at CERN, meant for integration with the Xsuite ecosystem. The new capabilities of the Python code are detailed and a thorough benchmark against existing codes is presented, for various machines of the CERN accelerator complex in different configurations.

The 3-GeV RCS (Rapid Cycling Synchrotron) at J-PARC (Japan Proton Accelerator Research Complex) simultaneously delivers high-intensity proton beam to the muon and neutron production targets at the MLF (Material and Life Science Experimental Facility) as well as to the MR (Main Ring). Beam loss mitigation is highly essential not only to keep the machine activation lower for maintaining a stable operation with high availability, but also to ensure a high-quality beam having a lower beam emittance and minimum beam halos. We have performed systematic numerical simulations and beam studies and implemented several measures, such as resonance corrections, optimization of the longitudinal and transverse paintings and also optimization of the betatron tune. We have obtained significant beam loss mitigation as well as beam emittance improvement for the beam delivered to both MLF and the MR. Recently, a transverse painting area of 50π mm·mrad has been increased to 100π mm·mrad implemented for the MR beam. This gives a half reduction of the average foil hitting of the circulating beam. As a result, not only the uncontrolled foil scattering beam losses but also the beam loss at the collimator have been reduced to half. Such improvements in the RCS have also been well recognized at both MLF and the MR by reducing the beam losses at the beam transport as well as each facility. The RCS has been continued a sustainable operation with record high of nearly 99% availability.

The P42 beamline transports 400 GeV protons from the CERN SPS between the T4 and T10 targets. A secondary particle beam is produced at the T10 target and transported along the K12 beamline to the experimental cavern ECN3, presently housing the NA62 experiment. In the context of the Physics Beyond Colliders (PBC) study, an increase of the beam intensity in P42 has been considered to provide protons to a future high-intensity fixed-target experiment in ECN3. For both its present usage and especially for the intensity upgrade, it is important to reduce beam losses to a minimum to decrease environmental radiation levels and protect equipment. In this study, simulations of P42 with the Monte Carlo software BDSIM, are used to demonstrate that beam losses in P42 are primarily driven by particle-matter interactions in material intercepted by the beam. The distribution of the simulated losses is compared to doses measured along the beamline in radioprotection surveys and beam loss monitors. Future mitigation strategies to reduce beam losses are then discussed and evaluated.

The Shanghai Light Source has been operated since 2009 to provide synchrotron radiation to 40 beamlines of the electron storage ring at a fixed electron energy of 3.5 GeV. The Shanghai Laser Electron Gamma Source (SLEGS) is approved to produce energy-tunable gamma rays in the inverse Compton slant-scattering of 100 W CO2 laser on the 3.5 GeV electrons as well as in the back-scattering. SLEGS can produce gamma rays in the energy range of 0.66 – 21.7 MeV with flux of 1e+5 – 1e+7 photons/s*. A positron source based on SLEGS is designed to produce positron beams in the energy range of 3 – 16 MeV with a flux of 1e+5 /s and energy resolution of ~7% with an aperture of 10 mm collimator. The positron generated has been simulated by GEANT4, uses a SLEGS gamma injected into a single-layer target, and a dipole magnet deflect positrons. Based on the energy-tunable SLEGS gamma rays, the optimized parameters at each gamma energy were simulated to obtain an energy-tunable positron source. We have confirmed positron generation in the commissioning. We plan to construct the positron source in the summer of 2024. We present the positron source based on results of simulation and test measurements.

Horizontal and vertical collimators will be installed in the Diamond-II storage ring to protect the ring components against undesired losses and radiation showers. Different loss mechanisms have been studied, including lifetime effects, RF trips, injection losses and kicker misfire. In this paper, we present the latest collimator layout and collimation efficiency. In addition, the risk of damage to the collimator blades has been studied for different materials using BDSIM.

In this study, we present the design of a candidate lattice for the Shanghai Synchrotron Radiation Facility Upgrade (SSRF-U) storage ring, targeting the soft X-ray diffraction limit. Due to its ultra-low emittance, intra-beam and Touschek scattering are significant and require attention. We conducted simulations to examine the emittance growth and beam lifetime of different machine configurations in the SSRF-U storage ring. Equilibrium beam emittance variations due to beam coupling and bunch lengthening were identified through simulations. Additionally, Touschek scattering and beam lifetime were calculated.

Recent progress of basic study on Harmonic nonlinear Compton scattering in Brookhaven National Laboratory Accelerator Test Facility (BNL ATF) will be reported. Experiment is conducted by counter collision of a multi TW CO2 laser and 60-70 MeV electron beam having 300-600 pC of charge per pulse. Experiment AE131 is intended for two aspects of experimental demonstrations. A: Nonlinear bi harmonic effect seen in external lasers having shorter wavelength such as Nd:YAG laser induced by a long wavelength intense CO2 laser at scattered photon energy of 100 keV range. B: Detailed study on the harmonic radiation induced by circularly polarized multi TW CO2 laser which potentially contain the Orbital Angular Momentum at photon energy of 10 keV range.

As compared to conventional travelling-wave (TW) structures, parallel-coupled accelerating structures eliminate the requirement for the coupling between cells, providing greater flexibility in optimizing the shape of cells. Each cell is independently fed by a periodic feeding network for this structure. In this case, it has a significantly short filling time which allows for ultrashort pulse length, thereby increasing the achievable gradient. In this paper, a design of an X-band parallel-coupled TW structure is presented in detail.

Johannes Gutenberg University Mainz is currently constructing a new electron accelerator that employs an energy recovery scheme. The Mainz Energy Recovery Superconducting Accelerator (MESA) will provide two modes of operation: the Energy Recovery (ER) mode, which will supply an internal gas target experiment, and the Extraction Beam (EB) mode, primarily used in the P2 experiment where MESA's spin-polarized electrons will be directed towards a target. As an Energy Recovery Linac (ERL), MESA shows potential as an accelerator for an Inverse Compton Scattering (ICS)-based gamma source. To anticipate the impact of the scattering on electron beam parameters, significant for energy recovery, a novel quasi-analytical simulation code, "COMPARSE", has been developed and used for the feasibility studies. The investigations examine various applications of ICS sources at MESA. This paper gives an overview of the results as well as the limitations and possibilities of the underlying mathematical approach.

Hefei Light Source (HLS) is a small and compact synchrotron light source with an electron beam energy of 800 MeV and a circumference of 66.13 m. The storage ring lattice adopts the Double-Bend Achromat (DBA) structure with 4 super periods. Considering the future upgrade of the injection system by using a nonlinear kicker (NLK), we optimize the dynamic performance of the storage ring. The optimization mainly aims at increase the dynamic aperture and beam lifetime, which helps improve the injection efficiency for the new injection scheme. While keeping the current layout of the lattice, the linear optics is also modified in order to improve its nonlinear performance. In this paper, we represent our work on the optimization of the HLS-II storage ring.

Cesium antimonide photocathodes are known for their ability to generate bright electron beams for various accelerator applications. Lab-grown polycrystalline cesium antimonides as well as Cs1Sb and Cs3Sb crystals are distinguishable; however, it remains unclear how the crystalline and other material properties of each govern the main photocathode properties such as quantum efficiency and mean transverse energy. Furthermore, photoexcited electrons undergo significant energy losses before being emitted from thin cesium antimonide films. This process is not well understood since there is very little room for scattering events within thin films. The generation of ultra-bright electron beams, capable of substantially enhancing the scientific potential of advanced accelerator applications, requires deep understanding of these and other fundamental mechanisms, which constrain photocathode performance and simultaneously determine the maximum attainable beam brightness. The purpose of this work is to use the Monte Carlo approach in a combination with Density Functional Theory to shed light on these mechanisms and provide the guidance for effective photocathode optimization.

Quasi-monochromatic gamma-ray beams are produced in the laser Compton slant-scattering at the Shanghai Laser Electron Gamma Source (SLEGS) of the Shanghai Synchrotron Radiation Facility(SSRF) [1,2]. The laser Compton slant-scattering was pioneered to produce X rays as early as in 1996 [3] and has more recently been used to produced gamma rays in the MeV region at UVSOR [4]. The slant-scattering makes the usage of energy-tunable gamma-ray beams compatible with that of the synchrotron radiation in synchrotron radiation facilities operated at a fixed electron beam energy worldwide. The SLEGS is designed to produce gamma rays in the energy range of 0.66 – 21.7 MeV with a flux of 1e+5 - 1e+7 photons/s [2]. We have conducted test runs of the slant-scattering in the commissioning of the beamline to confirm the designed energy tunability and flux [5]. After a more careful measurement and data processing of the γ ray energy spectra in 2023, the newest experiment results of the quality of gamma-ray beams in flux and bandwidth is obtained and will be present in this report. The gamma-ray flux is in a range of 1e+4 - 3e+5 cps in 60° - 120° and the energy-resolution is in the range of 6 - 18%.

The Shanghai Laser Electron Gamma Source (SLEGS) is one of the beamlines of the Shanghai Synchrotron Radiation Facility, which dedicate to producing gamma beams in the slant-scattering for the first time. After produced in the interaction area, gamma rays pass through a carefully designed Gamma Modulation System (GMS), which consists of a double collimator system, attenuator system, and X/gamma imaging system. The quasi-monochromatic gamma beams with an energy spread of 4.2-4.6% are produced at the target position by using an aperture of 2 mm of the double collimator system*. The flux of gamma beams is regulated by the gamma attenuator system. X/gamma imaging system is equipped with two beam-spot monitors, an X-ray camera MiniPIX and the gamma spot monitor. MiniPIX is used for imaging electron-induced bremsstrahlung to reflect the position of gamma beam indirectly. The gamma spot monitor is used to reflect the gamma spatial distribution directly. With the GMS the gamma beam have been successfully implemented on SLEGS, the obtained high-quality gamma beam has been applied to photoneutron validation experiments. The expected results confirm the reliability of SLEGS gamma quality.

The cathode test stand at LANL is utilized to test velvet emitters over pulse durations of up to 2.5 µs. Diode voltages range from 120 kV to 275 kV and extracted currents exceed 25 A and depend on cathode size and pulse duration. Current density measurements taken with scintillators or Cherenkov emitters produce inconsistent patterns that disagree with the anticipated beam profile. Several factors contribute to the measured beam distribution, such as electron scatter, X-ray scatter, and Snell’s law. Here, we present a range of experiments designed to evaluate both electron scatter and Cherenkov emission limits in efforts to optimize current density measurements. For electron ranging studies, metal foils of different densities and thicknesses are coupled with a scintillator, which is then imaged with an ICCD. Similarly, Cherenkov emission and Snell’s law are investigated through imaging materials with differing indices of refraction over a range of beam energies. MCNP6® modeling is utilized to further guide and evaluate these experimental measurements.

Ionization cooling stands as the only cooling technique capable of efficiently reducing the phase space of a muon beam within a short time frame. The optimal cooling parameters of a muon collider aim to minimize transverse emittance while simultaneously limiting longitudinal emittance growth, resulting in optimal luminosities within the collider ring. This study shows that achieving efficient cooling performance requires selecting the best initial muon beam parameters. Because for every transvere emittance there exist an optimal beam energy for ionization cooling. We present a technique that enables the determination of these optimal initial parameters through simulations and compare them with an improved analytical scattering model.

Within the context of a design study of a LINAC for ionization cooling, this paper presents the result of incorporating a scattering model in RF-Track (v2.1) for charged particles heavier than electrons. This inclusion enables simulations for applications like ionization cooling channels for muon colliders. Within RF-Track, a novel semi-Gaussian mixture model has been introduced to describe the deflection of charged particles in material. This innovative model comprises a Gaussian core and a non-Gaussian tail function to account for the effects of single hard scattering. To validate the accuracy of our results, we conducted a benchmarking comparison against other particle tracking codes, with the outcomes demonstrating a high level of agreement.

Neutron scattering experiments have undergone significant technological development through large area detectors with concurrent enhancements in neutron transport and electronic functionality. Data collected for neutron events include detector pixel location in 3D, time and associated metadata, such as sample orientation and environmental conditions. Working with single-crystal diffraction data we are developing both interactive and automated 3D analysis of neutron data by leveraging NVIDIA’s Omniverse technology. We have implemented machine learning techniques to automatically identify Bragg peaks and separate them from diffuse backgrounds and analyze the crystalline lattice parameters for further analysis. A novel CNN architecture has been developed to identify anomalous background from detector instrumentation for dynamical cleaning of measurements. Our approach allows scientists to visualize and analyze data in real-time from a conventional browser, which promises to improve experimental operations and enable new science. We have deployed a cloud based server, leveraging Sirepo technology, to make these capabilities available to beamline users in the control room.

Testing of space-bound microelectronics plays a crucial role in ensuring the reliability of electronics exposed to the challenging radiation environment of outer space. This contribution describes the beam optics studies carried out for the run held in November 2023 in the context of the CERN High-Energy Accelerators for Radiation Testing and Shielding (HEARTS) experiment. It also delves into an investigation of the initial conditions at the start of the transfer line from the CERN Proton Synchrotron (PS) to the CERN High Energy Accelerator Mixed-field (CHARM) facility. Comprehensive optics measurement and simulation campaigns were carried out for this purpose and are presented here. Using a validated optics model of the transfer line, the impact of air scattering on the beam size was quantified with MAD-X and FLUKA, providing valuable insights into the current performance and limitations for Single Event Effects (SEE) testing at CHARM.

The Los Alamos Neutron Science Center (LANSCE) accelerator uses charge exchange injection to accumulate a high-intensity proton beam in the Proton Storage Ring (PSR). H- ions are accelerated to 800 MeV and then stripped of their electrons by a thin foil at the ring injection site. The Monte Carlo N-Particle (MCNP) radiation transport code has been used to estimate the effect foil thickness has on the emittance growth of the ion beam. Results for the scattering angle of individual particles and emittance growth of the injected beam are presented for a range of foil thicknesses.

An increasing number of accelerators are pursuing FLASH radiotherapy, which promises to mitigate unwanted damage to healthy tissues by applying ultra-high dose rates. To reach this extreme intensity regime, it is necessary to maximize the transmission through the exit nozzle, apart from increasing the accelerator’s output beam current. Simultaneously, the delivered beam properties must satisfy certain quality criteria that clinical applications require, such as transverse homogeneity. For this reason, a Python-based software has been developed to optimize the design of double-scattering beam nozzles. For a user-defined set of incoming beam parameters, output field requirements and available materials, the tool searches for the most efficient scattering conditions utilizing a graphical interface. These conditions are then translated into distances and shaping of the scatterers, involving a combination of high and low-density elements in a multiple-ring arrangement. A solution for the treatment of eye tumors has been successfully calculated, implemented, and tested with beam, in order to demonstrate the capabilities of this approach.

A new cyclotron facility has been constructed at Thailand Institute of Nuclear Technology to provide proton beams with energy of 15-30 MeV for radioisotope production and material analysis. Due to requirements of particle induced X-ray emission (PIXE) and particle induced gamma-ray emission (PIGE) techniques that need a low-energy and low-intensity proton beam in range of 2-15 MeV and picoamperes as well as high detection sensitivity, the additional setup including an energy degrader, a collimator, a 30-degree separator magnet, and a slit, is employed for an in-vacuum irradiation beamline. In this work, we study the proton beam trajectory and beamline elements. The energy degrader made of aluminum has shown promising results in decreasing the beam energy while the energy spread of a secondary beam is significantly reduced by the following 30-degree separator magnet. Furthermore, the combination of the collimator and the slit lessens the beam current to proper values. To measure the proton beam current downstream, a copper Faraday cup will be used.

The X-ray Imaging Laboratory is a radiation test facility developed by Rapiscan systems at their facility in Stoke-On-Trent, UK. The X-ray Imaging Laboratory comprises two areas: the Test Facility and the Linac Development Area. The Test Facility is a state-of-the-art facility designed for subsystem and system level testing of x-ray imaging hardware utilizing normal conducting electron linacs with energies of up to 6MeV. The Test Facility is primarily focused on utilizing mature industrial linacs to produce x-rays for imaging validation. The Linac Development Area is a new facility focused on testing linear accelerator components and subsystems for a new generation of industrial electron linacs. The Linac Development Area includes a high voltage test area and a radiation test bunker. This allows for testing of critical components, such as modulators, in isolation in the high voltage test area and then as part of an industrial linac in the radiation test bunker.