The Relativistic Heavy Ion Collider (RHIC) was designed for head-on collisions in the Interaction Regions. However, RHIC operation in recent years necessitated crossing angles to limit collisions to a narrow longitudinal vertex region, which created operating conditions with a large Piwinski angle (LPA). The angles were implemented by adjusting the shunt currents of four dipoles, the D0 and DX magnets, near the IP. The longitudinal bunch profile often deviates from Gaussian due to the utilization of high-order RF cavities, adding complexity to calculating luminosity reduction with crossing angle. This paper introduces two methods for implementing crossing angles, discusses resultant aperture concerns, conducts numerical calculations of luminosity reduction, and compares these findings with experimental observations.

The luminosity of particle colliders depends, among other parameters, on the transverse profiles of the colliding beams. At the LHC at CERN, heavy-tailed transverse beam distributions are typically observed in routine operation. The luminosity is usually modelled with the assumption that the 𝑥-𝑦 planes are independent (i.e. statistically uncorrelated particle distributions between the planes) in each beam. Analytical calculations show that the solution of inverting 1D heavy-tailed beam profiles to transverse 4D phase-space distributions is not unique. For a given transverse beam profile, the distributions can be dependent (i.e. statistically correlated) or independent in the transverse planes, even in the absence of machine coupling. In this work, the effect of transverse 𝑥-𝑦 dependence of the 4D phase space distribution on the luminosity of a particle collider is evaluated for heavy-tailed beams.

Since the start of the Large Hadron Collider (LHC), dust-induced beam loss events resulted in more than hundred premature beam aborts and more than ten dipole quenches during proton physics operation. The events are presumably caused by micrometer-sized dust grains, which are attracted by the proton beams and consequently give rise to beam losses due to inelastic proton-nucleus collisions. Besides the events which trigger dumps or quenches, a large number of smaller dust events has been detected by the beam loss monitors every year. Although these events are not detrimental for physics operation, they are still carefully scrutinized as they give a better understanding about the correlation with beam parameters, about the long-term evolution of event rates, and about possible correlations with shutdown activities and the installation of new equipment. In this contribution, we present a summary of observations from the first three runs of the LHC.

Strong Hadron Cooling (SHC), utilizing the coherent electron cooling scheme, has been extensively investigated for the Electron Ion Collider (EIC). Throughout our cooling optimization studies, we realized that a Super-Gaussian electron bunch offers enhanced performance in comparison to a Gaussian bunch. Our approach involves initiating the electron beam distribution in a double peak form, transitioning them into a Super-Gaussian distribution due to the longitudinal space charge. Subsequently, a chicane within the linac section compresses the bunch to meet the required bunch length. We tuned a third harmonic cavity amplitude to reduce the nonlinear term of the chicane. Moreover, given the low initial current leading to a small but non-uniform slice energy spread, we evaluated utilizing laser heating techniques to achieve a uniformly distributed slice energy spread. In this report, we discuss the concepts and simulation results.

For the development of X-band deflecting structure at Shanghai Synchrotron Radiation Facility (SSRF), two units of X-band deflecting structures totally including six RF structures have been used on SXFEL successfully for ultra-fast beam diagnostics. The construction of another new FEL facility has started from 2018, which is named Shanghai high repetition rate XFEL and extreme light facility (SHINE). Four units of X-band deflectors will be installed on SHINE. The design and measurement of the first prototype has been finished, and the high power test will be carried out soon, in this paper, the design and measurement results will be presented.

We report on the status of a degrader device to generate large phase space beams for machine acceptance studies in the Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab. The degrader device consists of thin, low-Z targets to degrade the electron beam phase space through multiple scattering, two apertures to define the maximum transverse emittance, and a solenoid to aid in matching to the rest of the injector beamline. The engineering design of the degrader device and projected degraded beam phase space parameters obtained from simulation are presented.

Distributed-coupling structures has been proposed as an advanced type of high-gradient accelerators, RF power flow independently into each cavity.This method has few advantages such as high shunt impedance, superior power efficiency, and low costs. And the most distributed-coupling structures typically set 0° or 180° as the phase advance which can simplify the design.In this study we introduces a new-designed distributed-coupling structures with phase advance greater than 180°. This choice of angle will significantly reduce costs without affecting the shunt impedance.

Stationary CT is a novel CT technology to significantly improve scanning speed, by using distributed multiple ray sources instead of conventional helical rotation with single source. This work presents an S-band multi-beam accelerator as a multiple MV-level X-ray source for industrial stationary CT application. This accelerator consists of 7 parallel-distributed acceleration cavity and 6 coupling cavity, operating in pi/2 standing-wave mode with a centre frequency of 2998MHz. This structure can generate 0.7 MeV electrons with 100 mA peak current at each beamline according to the imaging requirement. The novel multiple high-energy X-ray source will fill in the blank of source requirements in industrial stationary CT application.

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 longitudinal distribution of the electron beam in the electron storage ring of the Electron-Ion Collider will be modified by the machine impedance. The modified distribution, combined with crab cavities may have an impact on the quality of the hadron beam during the collision. In this paper, we will explore the possible impact on the hadron beam quality with strong-strong and weak-strong beam-beam simulations.

One of the main methods to generate X-rays is to bombard metal targets with electron beams. However, this process introduces uncertainty in the electron transport, which leads to uncertainty in the position and momentum of the secondary X-rays. As a result, the focal spot of the X-rays is larger than the electron beam. In this paper, we use the Monte Carlo software Geant4 to investigate the conditions for minimizing the X-ray focal spot size. We assign different weights to the X-rays according to their energy components, based on the actual application parameters, and calculate the focal spot size for three target materials: lead, copper, and tungsten, finding that when the incident electron energy is in the MeV range and the electron source radius is 1 um, the mass thickness of the target of 1.935×10e-3 g/cm^2 is the limit for achieving the smallest equivalent focal spot size.

In a radiofrequency accelerating structure with ceramic insertion, high shunt impedance (162 megaohm/m) and high group velocity (3.1% of the speed of light) are achieved simultaneously. The ceramic insertion is in the form of a cylinder, sandwiched between copper endplates with the beam aperture opened at the center. We report our theoretical study on this novel type of traveling wave accelerating structure that operates with a 2pi/3-mode at 5.7 GHz. The high shunt impedance is realized by the low-loss, highly reflective ceramic insertion confining the accelerating mode at the center. The high group velocity, or fast filling time of the radiofrequency wave, is made possible by the side coupling slots designed with large dimensions. As a result, this novel traveling wave accelerating structure enhances the power efficiency significantly, by two means. The high shunt impedance allows providing a greater accelerating gradient with a given amount of radiofrequency power. The fast filling time allows an earlier start of the beam acceleration within each radiofrequency power pulse, thus leading to a higher duty factor of the accelerator beam production. This type of the structure design allows using metallic iris features, which minimizes the electric field magnitude witnessed by the ceramic component. We also discuss the scheme of using periodic permanent magnets to focus an electron beam in the accelerating structure. The unique radiofrequency coupler design is also addressed.

High field radio frequency (RF) accelerating structures are an essential component of modern linear accelerators (linacs) with applications in photon production and ultrafast electron diffraction. Most advanced designs favor compact, high shunt impedance structures in order to minimize the size and cost of the machines as well as the power consumption. However, breakdown phenomena constitute an intrinsic limitation to high field operation which ultimately affects the performance of a given structure requiring dedicated tests. The introduction of a recent design based on cryogenic distributed coupling structures working at C-band (~6 GHz) allows to increase the shunt impedance by use of alternative distribution schemes for the RF power while mitigating the breakdowns thanks to the low temperature. In this paper we introduce the plan for high field and breakdown tests envisioned for a simple two-cell version of the aforementioned structure. Moreover, we discuss the joining procedure utilized to unify the two fabricated halves of such a structure and relying on the diffusion bonding technique which constitutes an attractive alternative to the brazing approach.

Many of ion beams generated by the Electron Cyclotron Resonance Ion Source (ECRIS) originate from solid-state materials and undergo a conversion process to transition from a solid to a gaseous state before being introduced into the plasma. Established techniques for thermal evaporation encompass ovens and others. The primary objective is to advance oven technology targeting increased reliability, durability, efficiency, and an expanded temperature range. At the Facility for Rare Isotope Beams (FRIB), a specialized inductive High Temperature Oven (HTO) has been developed to ensure the consistent and reliable production of metallic ion beams. ANSYS simulations have been carried out to maximize the temperature inside the oven and to help select the materials used with the oven based on the analysis on the heat distribution. Off-line tests have shown that the oven operates durably at temperatures close to 2000°C, and on-line tests already demonstrated beam intensity as high as 52 eµA of 238U35+ and 60 eµA of 238U33+. This paper presents and discusses the design features, ANSYS simulations, off-line and on-line test results of the HTO.

In this paper, beam dynamics simulations in a compact 200 kV DC electron gun at Tsinghua University are carried out and pm·rad-scale low normalized transverse emittance is obtained in the preliminary results. Small emission areas and low initial electron energies contribute to the generation of beams with low transverse emittance. We used electrochemical etching to fabricate tips for cold field emitters and got several regularly shaped tips with a small radius of curvature of the apex in some attempts. We anticipate that sharp tips in high-gradient electron guns can provide high-quality electron beams for different applications, e.g. high spatial resolution electron microscopy.

A general theory of symplectic tracking under the influence of space charge force is not yet available, even if some specific solution was proposed [1, 2]. In this paper we will first review how the pull-back of the Lie transform can be used to self-transport the beam distribution and its associated electromagnetic potential under the effect of the space-charge. We will then classify the functions suitable for an iterative algorithm with the Lie transform. Those functions will be used to describe the electromagnetic potential of the space charge.

This study explores various neural network approaches for simulating beam dynamics, with a particular focus on non-linear space charge effects. We introduce a convolutional encoder-decoder architecture that incorporates skip connections to predict transversal electric fields. The model demonstrates robust performance, achieving a root mean squared error (RMSE) of $0.5\%$ within just a few minutes of training. Furthermore, this paper explores the feasibility of replacing traditional ellipsoidal methods with Gaussian envelope models for improved non-linear space-charge calculations. Our findings indicate that these advancements could provide a more efficient alternative to numerical space-charge methods in beam dynamics simulations.

The question of the mitigation of the Transverse Mode Coupling Instability (TMCI) by space charge has been discussed for more than two decades. Since few years, it has become clear that the ABS model, which has been often used in the past and which assumes an air-bag bunch in a square well, is not sufficient to properly describe the complexity of the interaction between impedance and space charge. Considering a more realistic longitudinal Gaussian distribution, a fully self-consistent treatment of space charge was performed few years ago using the circulant matrix model, which revealed the usual TMCI mechanism but with oscillation modes shifted both by impedance and space charge. In this paper, a non self-consistent treatment of space charge is analyzed, still using a Gaussian distribution, to look at the evolution of the coherent direct space charge modes. It is shown in particular that it leads to exactly the same result as the self-consistent treatment for space charge parameters below 1 and that it is a much better approximation than the ABS model for space charge parameters above 1, as it reveals clearly how the positive modes lead to negative tune shifts.

We report simulation results showing the use of sacrificial bunch charge to achieve high brightness in photoinjector beamlines designed for Ultrafast Electron Diffraction (UED) and Inverse Compton Scattering (ICS). The beam undergoes nonlaminar focusing during which the tails dynamically linearize the core’s transverse phase space. An aperture then removes the resulting diffuse tails, leaving a beam with high brightness. We employ this scheme in C-band photoinjector guns, whose high gradients are attractive for both low (UED) and high charge (ICS) applications. In our simulations we use a 1.6 cell gun with a peak field at the cathode of 240 MV/m. We start with negligible intrinsic emittance and use a multi-objective genetic algorithm to obtain a Pareto front minimizing bunch length and emittance. For ICS applications, we obtain an extremely small minimum emittance of 80 nm at a final charge of 250 pC per bunch and 1.44 ps rms bunch length. For a final bunch charge of 1e+5 electrons, typical for UED experiments, we obtain an emittance of 1.2 nm at an rms bunch length of 50 fs. Both results far exceed the brightness state of the art for these applications.

The TopGun photoinjector is a 1.6-cell C-band gun developed by the University of California, Los Angeles team. Originally optimized for 100 pC operation, its low emittance design has been our starting point. However, the Los Alamos National Laboratory (LANL) needs to operate with a 250 pC bunch charge while maintaining an emittance below 100 nm. The initial optimization of the high charge TopGun-like photoinjector design, intended for construction at LANL, has been previously reported. That design had a single objective: achieving the lowest possible emittance, which was attained at significantly longer bunch length, thereby limiting improvements in beam brightness. Here, we present a multi-objective genetic optimization of the high charge TopGun-like photoinjector design to obtain a Pareto front minimizing bunch length and emittance. We have successfully reduced the bunch length from 8.18 ps to 5.67 ps while maintaining similar emittance values.

Transfer maps of different ion optical elements are usually obtained via ray tracing methods without taking into account the imperfections and misalignments of the optics. Normally beam profile monitors do not measure the full 6D phase-space, but only a portion of it. To verify the beam phase-space, we have constructed an Ion Optics Test Stand (IOTS) that is located at the Low Energy Branch (LEB) of the Jozef Stefan Institute in Ljubljana, Slovenia [1]. The IOTS consists of two Allison emittance scanners (AES) [2] with an electrode sandwiched between them, and is supplied by the LEB with a variety of ion beams with energies up to 20 keV. This allows us to automatically measure the 6D beam phase-space before and after the electrode and determine the electrodes transfer map. We will discuss the status of the IOTS, the emittance scanners, electrode transfer map measurements with them, and describe an example of AES--Einzel lens--AES test configuration. We will also show how the phase-space measurements performed with the IOTS can be used as a training ground of Machine Learning (ML) tools designed for ion optics optimization with respect to a preferred transport metric.

Coherent synchrotron radiation has a significant impact on electron storage rings and bunch compressors, inducing energy spread and emittance growth in a bunch. While the physics of the phenomenon is well-understood, numerical calculations are computationally expensive, severally limiting their usage. Here, we explore utilizing neural networks (NNs) to model the 3D wakefields of electrons in circular orbit in the steady state condition. We demonstrate that NNs can achieve a significant speed-up, while also accurately reproducing the 3D wakefields. NN models were developed for both Gaussian and general bunch distributions. These models can potentially aid in the design and optimization of accelerator apparatuses by enabling rapid searches through parameter space.

One of the Grand Challenges in beam physics is development of virtual particle accelerators for beam prediction. Virtual accelerators rely on efficient and effective methodologies grounded in theory, simulation, and experiment. We will address one sample methodology, extending the understanding and the control of deleterious effects, for example, emittance growth. We employ the application of the Sparse Identification of Nonlinear Dynamical systems algorithm–previously presented at NAPAC’22 and IPAC’23–to identify emittance growth dynamics caused by nonuniform, empirical distributions in phase space in a linear, hard-edge, periodic FODO lattice. To gain further understanding of the evolution of emittance growth as the beam’s distribution approaches steady state, we compare our results to theoretical predictions describing the final state emittance growth due to collective and N-body mode interaction of space charge nonuniformities as a function of free-energy and space-charge intensity. Finally, we extend our methodology to a broader range of virtual and real experiments to identify the growth(decay) of (un)desired beam parameters.

Ongoing studies at the Spallation Neutron Source (SNS) Beam Test Facility (BTF) seek to understand and model bunch dynamics in a high-power LINAC front-end. The BTF has recently been upgraded with a reconfiguration from a U-shaped line to a Straight line. We report the current state of model benchmarking, with a focus on RMS beam sizes within the FODO line. The beam measurement is obtained via three camera/screen pairs in the FODO line. This presentation discusses the methodology and results of this measurement.

Beam profile measurements in the LHC and its injector complex show heavy tails in both transverse planes. From standard profile measurements, it is not possible to determine if the underlying phase space distribution is statistically independent. A measurement campaign in the CERN PSB was carried out to introduce cross-plane dependence in bunched beams in controlled conditions, in view of characterizing the LHC operational beam distributions. The results of the measurement campaign demonstrate how heavy tails can be created via coupled resonance excitation of the lattice in the presence of space charge, in accordance with predictions from the fixed line theory. The coupled resonance introduces dependence between the different planes, which persists after the resonance excitation is removed.

The Electron-Ion Collider (EIC) Hadron Storage Ring (HSR) will use strong hadron cooling to maintain the beam brightness and high luminosity during long collision experiments. An Energy Recovery Linac is used to deliver the high-current high-brightness electron beam for cooling. For the best cooling effect, the electron beam requires low emittance, small energy spread, and uniform longitudinal distribution. In this work, we simulate and optimize the longitudinal laser-beam distribution shaping at the photo-cathode, modeling space charge forces accurately. Machine parameters such as RF cavity phases are optimized in conjunction with the beam distribution using a genetic optimizer. We demonstrate the improvement to the cooling distribution in key parameters.

The alignment installation work of Hefei Advanced Light Facility (HALF) is usually carried out in tunnels. Calculate the key component points to the global coor-dinate system through coordinate conversion, and accu-rately adjust them to the corresponding coordinate values for alignment and installation. However, long and narrow tunnels can easily cause dense common points, resulting in a loss of accuracy. Therefore, to quickly and accurately obtain the coordinate transformation parameters, this article proposes a common point selection method with uniformity normalization and selects the optimal com-mon points set based on the normalized uniformity in different directions. The feasibility of this method was verified based on experimental data. The results show that the conversion parameters solved by this method are more accurate, avoiding accuracy loss due to aggregation in a certain direction, and are suitable for long and narrow tunnels.

The 3.0 GeV ALBA Synchrotron Light Source, in operation with users since 2012, is looking forward an upgrade aimed at enhancing the brightness and coherence fraction of the delivered X-ray beam. The Storage Ring (SR) will be completely renewed but we plan on keeping the same orbit length and the position of the ID source points. The energy of the electrons will be preserved and the same injector will be used. Major part of the Insertion Devices and Front Ends will be kept; new ones will feed additional long Beamlines (230m-275m), included on the project. The “dark period” is foreseen for 2030-2031. This paper presents the strategic plans being developed to test and assemble the new SR components, the dismantling of the present SR and the seamless installation of the upgraded SR. Emphasizing a cost-effective and time-efficient approach, we have started the planning by focusing on optimizing spaces and equipment movements necessary for the upgrade process.

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.

DESY is planning to upgrade PETRA III to a 4th generation light source. The magnetic lattice components are pre-installed and aligned on long girders before being installed in the tunnel. These long girders and the misalignment of the magnets pose a challenge for the PETRA IV lattice, including the storage of the beam in the ring. Commissioning simulations have been performed which showed that relatively high corrector strengths are required for the orbit correction system. A simulation study was performed to demonstrate the possibility of beam-based girder alignment correction to relax the corrector strengths during machine operation. The simulation results are presented and then discussed for later implementation.

We calculate the coherent radiation of a modulated beam in a short resonantly tuned undulator taking into account the finite transverse size and the angular spread of the beam. The result allows to optimize the radiation by controlling the Twiss parameters in the undulator.

In anticipation of the Eupraxia@SPARC_LAB project at the INFN Frascati National Laboratories, an intensive testing and validation activity for the X-band RF system has commenced at the TEX test facility. The Eupraxia@SPARC_LAB project entails the development of a Free-Electron Laser (FEL) radiation source with a 1 GeV Linac based on plasma acceleration and an X-band radiofrequency (RF) booster. The booster is composed of 16 high-gradient accelerating structures working at 11.994GHz. All radiofrequency components comprising the basic module of the booster, from the power source to the structure, must undergo testing at nominal parameters and power levels to verify their reliability. For this reason, since 2021, several experimental runs have been conducted to test various components in X-band technology at the TEX facility. This paper presents the results obtained thus far from the different experimental runs, and it also outlines the future upgrade of the facility, which will enhance testing capabilities and the future prospects of the facility itself.

For the future multi-TeV muon collider, ionization cooling is a critical step to achieve the required beam emittance for a proton-driven muon beam. Ionization cooling of intense muon beams requires the operation of high-gradient, normal-conducting RF structures in the presence of strong magnetic fields. The MAP modular cavity study at Fermilab has demonstrated the RF breakdown threshold at 13 MV/m for copper surface and 50 MV/m for beryllium surface in a 3 T solenoid B field. Based on these surface E field limits, we design a new 805 MHz copper cavity with thin curved beryllium windows that can achieve a gradient (without the transit time factor) of ~27 MV/m, which is comparable to the current 6D cooling lattice design. We also explore the distributed coupling for feeding the RF power to multiple cavities in the cooling lattice to accommodate the tight space in the superconducting solenoids. This cavity design study can be applied to the muon collider demonstrator program to experimentally evaluate the 6D muon emittance cooling.

Future colliders will require injector linacs to accelerate large electron bunches over a wide range of energies. For example the Electron Ion Collider requires a pre-injector linac from 4 MeV up to 400 MeV over 35 m*. Currently this linac is being designed with 3 m long traveling wave structures, which provide a gradient of 16 MV/m. We propose the use of a 1 m distributed coupling design as a potential alternative and future upgrade path to this design. Distributed coupling allows power to be fed into each cavity directly via a waveguide manifold, avoiding on-axis coupling**. A distributed coupling structure at S-band was designed to optimize for shunt impedance and large aperture size. This design provides greater efficiency, thereby lowering the number of klystrons required to power the full linac. In addition, particle tracking analysis shows that this linac maintains lower emittance as bunch charge increases to 14 nC and wakefields become more prevalent. We present the design and fabrication of this distributed coupling structure, as well as cold test data and plans for higher power tests to verify on the structure's real world performance.

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.

The non-evaporable getter (NEG) coatings provide conductance-free evenly distributed pumping, low thermal outgassing rates, second electron yield, and photon-and electron-stimulated desorption. NEG coatings are crucial for achieving ultrahigh vacuum in fourth-generation diffraction storage ring vacuum systems. TiZrV thin films were deposited onto elongated CuCrZr pipes for this investigation. The influence of various deposition parameters on the microstructure and vacuum properties of NEG coatings was investigated. The microstructure, surface topography, roughness, and phase composition were evaluated using Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), Atomic Force Microscope (AFM), and X-ray Diffraction (XRD), respectively. Furthermore, the activation performance of the TiZrV films was investigated in relation to deposition parameters.

A superconducting radio frequency (SRF) cryomodule (CM) for the International Linear Collider (ILC) Technology Network (ITN) is being developed at KEK. In the scope of this, a waveguide system is being designed. Its main features are a low center of gravity, a reduced number of corners and waveguide elements, and a compact bellow for connecting it to the input power coupler. Furthermore, the waveguide layout was designed to stay within the CM. This will avoid interference between components in the case of a multi-CM assembly. It is planned to adapt both the waveguide system and the installation process for the ITN. Analytical calculations and simulations have shown that most of the reflected power is dissipated in the load of the variable hybrid on removing the circulator. Thus, in the initial layout of the waveguide, the circulator is strategically installed to allow a future replacement with an H-corner integrated with a directional coupler, without disrupting the other waveguide components. Furthermore, a low-power test on a similar waveguide system showed that analytical calculations and simulation matched the measured values well.

The ESRF-EBS injection is performed with a standard off-axis injection scheme consisting of two in-air septa S1/2, one in vacuum septum S3 and four kicker magnets K1 to K4 to generate the injection bump. We can achieve 80% efficiency with this scheme. Despite many modifications and adjustments which allow the reduction of the perturbation, some beamlines are still affected. The Non-Linear Kicker could be a solution to this problem because it acts only on the injected beam. This paper reports on the magnetic design of the Non-Linear Kicker, including the octupole like Magnetic field simulations, magnetic forces calculations and mechanical tolerance optimizations.

Research on a novel permanent quadrpole magnet (PQM) design is introduced in this paper. It can make the quadrupole magnetic field gradient continuously adjustable by modulating several permanent magnet blocks. Four poles of the magnet inform an integral whole to ensure good structural symmetry, which is essential to obtain high-quality quadrupole magnetic field permanent quadrupole magnet. Series of simula-tion calculations have been done to study the effects of four distinct types of pole position coordinate errors on the central magnetic field. By juxtaposing these results with those derived from optimal design scenario of PQM, the study underscores the critical role that pole symmetry plays in this context. Two integrated design methodologies were proposed, with one of the designs undergoing processing and coordinate detection. The results indicate that this design, is capable of meeting the specified requirements. This design effectively ad-dresses the issue of asymmetrical pole installation, thereby ensuring to a certain extent that well-machined pole can generate a high-quality magnetic field.

This study examines Laser Engineered Surface Structures (LESS) in the context of their potential application within particle accelerators. These structures are investigated due to their efficient reduction of secondary electron yield to counteract the formation of electron clouds, a phenomenon detrimental to accelerator performance. A critical aspect of their evaluation involves understanding their radio-frequency characteristics to determine their influence on beam impedance. LESS involves intricate surface modifications, integrating etched grooves and deposited particulates, resulting in a complex surface topology. Measurements are conducted on two distinct surface patterns, from which particulates are then removed with incremental cleaning. Acquired data form the basis for mathematical models elucidating observed results. Novel approaches are investigated in addition to several established surface roughness models, including analysis of geometrical attributes of the surface topology and the associated electric currents. The aim is to develop a framework that describes roughness's influence across varying scales to assist in selecting appropriate treatment parameters.

An 820 mA CW positive ion source is being developed to produce Mo-99 using the fusion of deuterium and tritium ion beams on a rotating target to produce neutrons for use in the production of radiopharmaceuticals. The ion source consists of an RF plasma source, a multi-aperture extractor, and 300 kV accelerating column. This paper will describe a simulation study of the beam through the extractor grid and the accelerator to the target. The uniformity of beam distribution on the target is an important aspect of the simulation.

In the final cooling stages for a muon collider, the transverse emittances are reduced while the longitudinal emittance is allowed to increase. In previous studies, Final 4-D cooling used absorbers within very high field solenoids to cool low-momentum muons. Simulations of the systems did not reach the desired cooling design goals. In this study, we develop and optimize a different conceptual design for the final 4D cooling channel, which is based on using dense wedge absorbers. We used G4Beamline to simulate the channel and Python to generate and analyze particle distributions. We optimized the design parameters of the cooling channel and produced conceptual designs (corresponding to possible starting points for the input beam) which achieve transverse cooling in both x and y by a factor of ~3.5. These channels achieve a lower transverse and longitudinal emittance than the best design previously published.

Recently, the heavy ion synchrotron SIS18 at GSI was for the first time operated with a dual-isotope beam, made up of 12C3+ and 4He+. Such a beam can be used to improve carbon radiotherapy by providing online information on dose deposition, where the helium ions serve as a probe beam traversing the patient while depositing a negligible dose. For this, the accelerator has to deliver a slowly extracted beam with a fixed fraction of helium over the spill. The difference in mass-to-charge ratio of 4He compared to 12C is small enough to permit simultaneous acceleration and to make the two isotopes practically indistinguishable for the accelerator instrumentation. Yet, it may cause a temporal shift between the two components in the spill owing to the sensitivity of slow extraction to tiny tune variations. We investigated different extraction methods, and examined the time-wise stability of the dual-isotope beam with a beam monitoring setup installed in the GSI biophysics experiment room. A constant helium fraction was obtained using transverse knock-out extraction with adjusted chromaticity.

GL2000 Gabor-lens (GL)[1, 2] is a 2-m long device constructed and successfully operated at Goethe University. The confined electron column is much longer compared to previous constructed lenses and offers unique opportunity for investigation of electron cloud dynamics. Especially, kind of fingertip stopband structures were precisely measured in production diagram (operation function) in the year 2023 [2]. This fully reproducible behavior and dependence on a rest gas pressure left unexplained. For this purpose, a large scale multi-particles simulation PIC(particle-in-cell)-code was written in C++ and implemented on FUCHS-Cluster of the Goethe University. The main objective is to find an optimal operation parameter set for a stable operation of GLs, which is crucial for high energy hadron beam transport and focusing. Further topic will be investigation of possible longitudinal handling of bunched ion beams. The first simulation result will be presented and discussed.

During the Long Shutdown 2, the two internal dumps were replaced and successfully integrated into the CERN Proton Synchrotron operation to withstand the intense and bright beams for the High-Luminosity LHC. They function as safety devices, designed to swiftly intersect the beam’s trajectory and effectively stop the beam over multiple turns. A significant challenge arises from their limited energy absorption capacity. Previous studies indicate that at the maximum PS beam energy of 26 GeV, only about 7% of the energy is absorbed by the dumps upon their insertion. This study, employing a combination of the FLUKA and SixTrack simulation code chain, evaluates the absorbed dose in downstream elements in view of the projected increase of beam intensities, according to the LHC injector upgrade parameters, and explores the feasibility and potential benefits of implementing shielding as a mitigation measure.

High Power Targetry (HPT) R&D is critical in the context of increasing beam intensity and energy for next generation accelerators. Many target concepts and novel materials are being developed and tested for their ability to withstand extreme beam environments; the HPT R&D Group at Fermilab is developing an electrospun nanofiber material for this purpose. The performance of these nanofiber targets is sensitive to their construction parameters, such as the packing density of the fibers. Lowering the density improves the survival of the target, but reduces the secondary particle yield. Optimizing the lifetime and production efficiency of the target poses an interesting design problem, and in this paper we study the applicability of Bayesian optimization to its solution. We first describe how to encode the nanofiber target design problem as the optimization of an objective function, and how to evaluate that function with computer simulations. We then explain the optimization loop setup. Thereafter, we present the optimal design parameters suggested by the algorithm, and close with discussions of limitations and future refinements.

Our focus centers on numerical investigation into the transient response of optics when subjected to instantaneous heat deposition. The heat load deposited onto crystal optics, coupled with the emission of strain waves, has the potential to induce crystal deformation and vibrations. These phenomena carry detrimental consequences for optic performance, particularly in terms of wavefront preservation—an essential criterion for coherent XFEL beams. Our research involves an evaluation of optical performance in terms of the Strehl ratio at delay time. Ultimately, we aim to provide recommendations for establishing upper bounds on pulse energy and repetition rates during XFEL operation. These guidelines will play a pivotal role in optimizing XFEL performance while safeguarding wavefront integrity, thus advancing the capabilities of coherent X-ray beams in scientific and technological applications.

Most particle accelerators utilize beams with a charge density concentrated in the center of the bunch in real 3-dimensional space and the 6-dimensional phase space. In this work, by enhancing the space-charge forces in the photo-cathode injector of the Compact Linear Electron Accelerator for Research (CLEAR) at CERN, we produce electron bunches with a “bubble-like” shape, with a charge density mostly concentrated on the outside shell. We demonstrate that the dynamics of such beams can be tailored to achieve stable uniformity in the coordinate and momentum transverse planes simultaneously. This would allow reaching a uniform dose distribution without a severe loss of particles which is of the great interest in the irradiation community. Additionally, we investigate the potential benefits of bubble-beams across several accelerator pillars: for driving light sources, for advanced acceleration technologies, and for particle colliders.

SSRF (Shanghai Synchrotron Radiation Facili-ty)/SXFEL (Shanghai Soft X-ray FEL) Facility has de-veloped an advanced variable polarization transverse deflecting structure TTDS (two-mode transverse deflect-ing structure) to perform variable polarization based on the design of a dual-mode RF structure. The 15-cell prototype of the TTDS was fabricated at SSRF/SXFEL. Because the two modes operate in the same structure, any geometric change will affect both modes. A new RF design of the regular cell is proposed to improve rf per-formance. The two modes are coupled independently in two pairs of side coupling holes. The work presented in this paper is focused on the new design and the rf param-eters compared with the initial design.

A new S-band photocathode RF gun proposed for ultrafast electron diffraction (UED) has been designed and optimized. The electron gun works at pi mode and the operating frequency is 2.998GHz. The pulsed RF power loss is 3.2MW and the final kinetic energy of the electron beam is 3.5MeV. The RF gun works at high duty factor of 0.2% and the average power loss reaches 6kW. We have used ASTRA, a space charge tracking algorithm to simulate the beam dynamics and improve the bunch properties. By comparing the simulation results under different conditions, we found that the electron beam has good properties both transversely and longitudinally under some conditions. The simulation of bunch properties helps improve spatial-temporal resolution of UED.

Low energy electron bunches experience emittance growth due to space charge. This effect can lead to large emittances which are unacceptable for a facility like PERLE at IJCLab. PERLE will be an ERL test facility circulating a high current electron beam. The traditional method to reduce emittance due to this effect is already planned for the PERLE injector, this has a limit of how small the emittance can be reduced to. This limit is defined by the quality of the bunch as it is upon production at the cathode. The transverse and longitudinal properties of the laser pulse incident on the cathode defines some characteristics of the bunch, to which the space charge effect is related. In addition, the complex evolution of the bunch along the injector could result in optimal laser parameters which are different from the simple flattop distribution currently simulated. Presented here are simulation-based studies of the bunch charge distribution at the cathode and its subsequent evolution along the injector. An optimization of the laser parameters which create the bunch is also performed. We find that there is an optimal bunch charge shape which corresponds to minimal emittance growth.

The PERLE (Powerful Energy Recovery Linac for Experiments) project requires an injector capable of delivering a beam current of 20 mA at a total beam energy of 7 MeV with 500 pC bunches. These requirements present challenges for achieving the high quality beam required for the main ERL loop. At low energy and high bunch charge, the electron bunches will predominantly experience emittance growth due to the space charge effects. The compensation of this emittance growth will be performed with the traditional method of two solenoids a single bunching cavity and a linac to reach the intended injection energy. Additionally, the control of longitudinal and transverse bunch size must be performed to meet the requirements at the end of the injector. For stable operation of PERLE a rms bunch length of < 3 mm is required, with transverse emittances < 6 mm·mrad and acceptable transverse size. Presented here is the re-optimization of the injector settings used during commissioning for two alternative DC photoguns. It is found that the former cathode does not perform to the standard of previous optimizations. However, a newly procured cathode when optimized can meet the requirements for PERLE.

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.

The BPM feedthroughs were manufactured and tested at the vendor and the APS lab. All feedthroughs were sorted in groups of four according to their capacitance. Four feedthroughs with close capacitance were welded to the housing in an assembly. The assemblies were measured in the APS lab to confirm their electrical performance acceptable and their x/y offsets were calculated according to VNA data. After the BPM assemblies were installed in the SR, they were measured again to verify their connections. The x/y offsets including the cables were compared with the previous data and will be used as the reference in beam commissioning. The testing results at the vendor, APS lab and APS-U SR were analyzed.

Observation of Schottky signals provides information on important beam and machine parameters, such as transverse emittance, betatron tune, and first-order chromaticity. However, the so-far developed theory of Schottky spectra does not include the impact of the higher-order chromaticity, known to be non-negligible in the case of the Large Hadron Collider (LHC). In this contribution, we expand the theory of Schottky spectra to also take into account second-order chromaticity. Analytical results are compared with macro-particle simulations and the errors resulting from neglecting second-order chromaticity are assessed for the case of the LHC.

Beam tomography is a method to reconstruct the higher dimensional beam from its lower dimensional projections. Previous methods to reconstruct the beam required large computer memory for high resolution; others needed differential simulations, and others did not consider beam elements' coupling. This work develops a direct 4D reconstruction algorithm using Markov Chain Monte Carlo.

Accurate beam emittance and transverse phase space measurement are crucial for obtaining high-quality sample information in Ultrafast Electron Diffraction (UED). Traditional methods rely on general initial assumptions about the electron beam's phase space and lack specific distributions. The transverse phase space reconstruction technique based on the Computed Tomography (CT) algorithm eliminates the need for prior assumptions, resulting in more precise measurements. In this paper, we utilize an Algebraic Reconstruction Technique (ART) algorithm for HUST-UED, enabling the reconstruction of the beam transverse phase space distribution at the sample location and further facilitating system optimization.

To realize very precise measurement of the muon spin precession frequency in the level of sub-ppm, a muon beam is injected into a precisely adjusted storage magnet of sub-ppm uniformity via “Three-dimensional spiral beam injection scheme [1]” at J-PARC muon g-2/EDM experiment. This injection scheme requires a strongly X-Y coupled beam which is applied by eight rotating quadrupoles on the 10m of beam transport line [2]. Currently we have two scenarios of set of rotation angles (1) 45 or 60 degrees fixed, (2) any angles. In this presentation, strategy to precise control of the X-Y coupling at the beam transport line is discussed: how to control/monitor X-Y coupled phase space with eight rotatable quadrupole magnets including its alignment requirements for the case of (1) and (2). Results of alignment of the newly developed mount system for the rotating quad is also introduced. A pair of dedicated magnets called active shield multipole magnet (ASXM) will be set at the entrance and the exit of the beam channel of the storage magnet yoke. These devices will guarantee how well the beam phase space is matched with requirements at the reference point inside the storage magnet [3].

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.

Generative models can be trained to reproduce low-dimensional projections of high-dimensional phase space distributions. Normalizing flows are generative models that parameterize invertible transformations, allowing exact probability density evaluation and sampling. Consequently, flows are unbiased entropy estimators and could be used to solve the high-dimensional maximum-entropy tomography (MENT) problem. In this work, we evaluate a flow-based MENT solver (MENT-Flow) against exact maximum-entropy solutions and Minerbo's iterative MENT algorithm in two dimensions.

In-vivo dosimetry is essential to deliver precise doses to patients in ion beam therapy. Real-time dose monitoring without disturbing the beam improves patient safety and treatment efficiency. It is critical for emerging treatment modalities like FLASH therapy due to the narrow dose tolerance. Existing real-time dosimetry devices are invasive to beam, necessitating a non-invasive dosimetry solution. The gas-jet based beam profile monitor developed at the Cockcroft Institute (CI) is being studied for application in medical accelerator facilities. Recent measurements at the Dalton Cumbrian Facility, UK yielded promising results for beam monitoring at energies equivalent to medical beam. These studies have indicated the need to improve the gas-jet based Ionization Profile Monitor (IPM) to monitor dose in real time. A new IPM detector system is under development at CI to reduce the monitor size and complexity, and increase its sensitivity, resulting in fast acquisition, paving the way for real-time in-vivo dose monitoring. This contribution presents the design of the optimized IPM and its working principle based on electrostatic field and particle trajectory simulations.

First proof-of-principle steady-state microbunching (SSMB) experiment proved that SSMB has the potential to produce high average power short wavelength light. Tsinghua University has proposed a conceptual design for the future SSMB accelerator light source. A bunch train with an average current of 1 A is required in the electron injector for the future SSMB light source with a bunch spacing of 350 ps. It is essential for diagnosis to measure each bunch in the bunch train. A method of using a fast kicker to measure different bunches simultaneously is proposed in this paper. By using a fast-rising edge power supply, the kicker can give different electron bunches different kick angles, allowing different bunches to be detected on the screen simultaneously. This paper presents measurement methods for the transverse distribution, energy spread, longitudinal phase space, and emittance, along with corresponding simulation results.

LhARA, the Laser-hybrid Accelerator for Radiobiological Applications, is a proposed facility for the study of radiation biology. The accelerator will deliver ions at ultra-high dose rates and requires real-time measurement of the dose distribution. We have developed an ion-acoustic dose mapping system that exploits the acoustic waves generated by the beam’s energy deposition. A proposed proof-of-principle experiment is presented. A water-based phantom features a beam entry window sealed with Kapton. Three ports located on three orthogonal sides mount transducer arrays for detecting the acoustic waves. To calibrate their acoustic response, a liquid scintillator will be added to the water and its luminescence arising from the energy deposited by the beam is imaged by two cameras, positioned perpendicularly to each other. The acoustic wave generation and detection have been simulated in Geant4 and k-Wave, and the optical system in OpticStudio. The simulation shows precise reconstruction of the 3D deposited energy distribution using the acoustic and optical systems should be obtained in the proposed design. Combining these will yield a real-time calibrated dose map in the experiment.

Coherent synchrotron radiation (CSR) in linear accelerators (linacs) is detrimental to applications that require highly compressed beams, such as FELs and wakefield accelerators. However, traditional measurement techniques lack the precision to fully comprehend the intricate multi-dimensional aspects of CSR, particularly the varying rotation of transverse phase space slices along the longitudinal coordinate of the bunch. This study explores the effectiveness of our generative-model-based high-dimensional phase space reconstruction method in characterizing CSR effects at the Argonne Wakefield Accelerator Facility (AWA). We demonstrate that the reconstruction algorithm can successfully reconstruct beams that are affected by CSR.

Transverse deflection structures (TDS) have been widely used as diagnostic devices to characterize longitudinal properties of electron bunches in a linear accelerator. However, the conventional TDS can only measure either the horizontal or the vertical slice envelopes of electron bunches. In order to give full control of the angles of the transverse streaking field inside of the TDS to characterize the projections of the beam distribution on different transverse axes, we numerically investigate an X-band TDS with variable polarization in this paper. Through variable streaking direction, the orientation of the streaking field of the TDS is adjusted to an arbitrary azimuthal angle. This helps facilitate the development of next-generation TDS for the characterization of electron bunches, such as slice emittance measurement on different planes.

During the operation of a muon collider in an underground tunnel, most circulating muons decay into an electron (or positron) and a neutrino-antineutrino pair, resulting in a narrow disk of high-energy neutrinos emitted radially in the collider plane and emerging on the Earth’s surface at distances of several km. Thus, dedicated studies are required to assess any potential radiation protection risks to the public due to the interaction of such neutrinos near the surface. This work presents a set of FLUKA Monte Carlo simulations aimed at characterizing the radiation showers generated by the interactions of high-energy neutrinos from TeV-scale muon decays in a reference sample of soil. The results are expressed in terms of effective dose in soil at different distances from the muon decay, quantifying the peak dose and the width of the radiation cone, for beam energies of 1.5 TeV and 5 TeV. The implications of these results for realistic muon collider scenarios are discussed, along with possible methods to mitigate the local neutrino flux.

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.

Generation of a muon beam at a Muon Collider requires relatively short, high-charge proton bunches. They are produced in a high-average-power proton driver by first accumulating a proton beam from a super-conducting linac, then bunching the beam and finally compressing and combining the bunches into a single high-intensity proton pulse. All of these beam formation stages involve handling of unprecedentedly high beam charges. Validation of these intricate beam manipulations requires better understanding of extreme space-charge effects and experimental demonstration. A facility perhaps most closely resembling the proton driver configuration and beam parameters is the Spallation Neutron Source (SNS) accelerator complex at Oak Ridge National Laboratory (ORNL). Considering the energy scaling of the space-charge parameters, many of the beam formation steps planned for the proton driver can be experimentally checked at the SNS at the relevant space-charge interaction levels. This paper discusses potential proton driver and other muon-collider-related R\&D at the SNS.

A local H- /p source is operated at the CERN Extra Low Energy Antiproton (ELENA) decelerator for commissioning the ring and subsequent electrostatic transfer lines toward the experiments. For proper optics characterization, it is important to have a detailed knowledge of the H- beam parameters at the source. Phase space tomography techniques were applied to reconstruct the beam distribution at the measurement point, which was then tracked backward to the H- source using symplectic field maps to calculate the beam matrix. Due to the presence of an ion switch a highly non-linear behavior with significant deviation from the linear model was observed. The SIMPA tracking code allows EM fields in the transfer line to be treated continuously and as a whole.

In the Large Hadron Collider (LHC), intra-beam scattering (IBS) is one of the main drivers of longitudinal emittance growth during the long injection plateau. With the halo of the longitudinal bunch distribution being close to the separatrix, IBS consequently drives beam losses by pushing particles outside the RF bucket at the flat-bottom. As IBS and beam losses impose a requirement on the minimum RF bucket size, this mechanism has an important impact on the RF power requirements for the High Luminosity (HL-) LHC. In this contribution, the effect of IBS is introduced in the Beam Longitudinal Dynamics (BLonD) tracking code. This numerical model is then benchmarked against analytical estimates, as well as against beam measurements performed in the LHC. The impact of IBS-driven losses on the RF power requirements is discussed through the correlation between the time spent at flat-bottom and the average bunch length, which translates into start-of-ramp losses.

Particle tracking serves as a computational technique for determining the mean field of dynamically tracked charged macroparticles of a particle beam within an accelerator. Conventional solver tend to neglect collisionality, resulting in loss of relevant information (particle and momentum redistribution). In this study, macro-particle collisions are incorporated into a 3D Poisson solver. In the previous studies, identifying close particles have been performed in a static condition (IPAC23-Macroparticle collisionality in PIC solver). The requirement to uphold energy momentum within a dynamic tracking is initiated in simple lattices and the results are presented. A comparison with analytic model of the Bjorken-Mtingwa or Conte-Martini is included to verify.

Profile Monitor (PR) is used to observe and measure the beam profile in the Linac and transport line of the High Energy Phone Source (HEPS). To obtain more precise results, we implemented several widely used fitting algorithms in the framework Pyapas. We carried out detailed testing and comparison of these fitting methods based on simulated results and actual measurement data, respectively, and found the most suitable method under different beam conditions. These methods have been used in various applications for HEPS commissioning, including emittance measurement, energy and energy spread measurement, and RF phase scan. This paper provides an introduction to these algorithms. Subsequently, taking the emittance measurement application as an example, the results of error analyses are presented.

The study investigates the radiation attenuation performance of five ternary glass systems with varying chemical compositions: 50P2O5-(50-x)BaO-xEu2O3, where x = 0, 1, 2, 4, and 6 mol%. It utilizes theoretical and Monte Carlo methods to determine shielding parameters such as attenuation coefficients, mean free path, value layers, electron densities, conductivity and neutron removal cross-sections across an energy range from 1 keV to 100 GeV. In addition to these analyses, the study explores kinetic energy stopping potentials and projected ranges of ions (H+, He+, and C+) through the Stopping and Range of Ions in Matter database. Furthermore, research evaluates the dose rate attenuation behaviour and trajectories of photons bombarded from 137Cs and 60Co sources using Particle and Heavy Ion Transport code System. Obtained results show that sample: 50P2O5-44BaO-6Eu2O3 with higher Eu3+-doped glass has a potential for radiation shielding application among selected samples and is comparable with previously recommended, tested polymer and glass samples.

T-mapping diagnostic system is an indirect method to detect the internal surface of superconducting cavity during vertical testing. When superconducting cavity is powered, T-Mapping can detect the thermal instability and thermal collapse caused by defects. The goal of the project is to develop temperature detection devices that are highly accurate and easy to install. The development of the equipment plays a supporting role in the production of superconducting cavity, and can intuitive feedback the defects in the machining assembly, which is conducive to the improvement of the processing technology.

In the context of the High Field Magnet programme, the 12 T Nb3Sn activity aims to design and manufacture a 2-meter-long, 12 T, cosθ, double aperture dipole. To reach magnetic fields higher than 10 T in accelerator magnets, brittle epoxy-impregnated Nb3Sn Rutherford cables are employed, which makes it difficult to predict the coil's mechanical limit and, in extenso, the magnet's performance. To tackle this challenge, expensive procedures are often implemented. The 12 T mechanical design presented in this paper aims to prioritize intrinsically safe structures and minimize the number of components. This approach is intended to counteract issues stemming from fabrication tolerances and assembly tool misalignment. To prevent coil over-compression, mechanical stoppers are integrated within the magnet structure. The design is committed to focus on solutions that can be applied on short demonstrators but also scaled to long magnets that need to be produced in large quantities in series. This paper aims to introduce the magnet's mechanical design, its underlying principles, and the advantages it offers.

In times of climate change and with increasing challenges of the power grid stability due to unstable renewable energy sources, it is not sufficient to know the electric energy consumption of accelerator facilities. In order to optimize the operation of the research infrastructure in terms of stability, reliability and sustainability, the knowledge of the dynamics of energy consumers, and generators is mandatory. Since a few years, KIT's accelerator teams collaborate with its EnergyLab 2.0, Europe's largest research infrastructure for renewable energies, within the KIT test field for energy efficiency and grid stability of large-scale research infrastructures (KITTEN). At the research accelerators KARA and FLUTE a dense network of power meters, more than 100 sensors of different kind, operate to observe from individual components to infrastructural components and the central electricity distribution. With more than one year of data taking for most of the sensors, we are already able to quantify implemented energy-savings measures. In this contribution the findings of the installation and the first analysis and savings within the more than one year data taking will be presented.

The National Synchrotron Radiation Research Center (NSRRC) has conducted a study on the magnetic circuit design of a high-temperature superconducting undulator (HTSU). This study explores the potential use of second-generation high-temperature superconducting (2G-HTS) materials in undulator magnet, which offer advantages such as higher current density and operating temperature. To evaluate the feasibility of HTSU design, a preliminary magnetic circuit analysis has been conducted. The simulation of the HTSU involved the use of several commercial 2G-HTS tapes with different widths. Insulating and non-insulating HTS tapes were compared to evaluate their effects on current density and magnetic field. Additionally, the maximum field strength on the surface of the tape was determined to establish the optimal operating temperature and current density for the HTSU. These simulation results provide valuable insights for optimizing the design and performance of the HTSU, ultimately contributing to advancements in particle accelerator technologies.

The concept of a single unified model for designing accelerator magnets has long been sought. Any meaningful virtual twin model must embody the ability to simulate the electromagnetic, thermal and structural performance of the device, as well as retaining the full geometric, materials and manufacturing information. Not only this, but the virtual twin must be able to respond to a design change and identify that either some of the simulations need to be repeated to capture the effect of the design change or to reliably identify that the last simulation results available were from a previous virtual prototype. As the fields of interest in these magnets are particularly sensitive to small geometric perturbations, accurate simulation capabilities are required to capture both electromagnetic and mechanical effects. Finally, the ability to optimize the design accounting for input from multiple areas of physics is paramount. In this paper, the authors report how the Dassault Systemes 3DEXPERIENCE Platform has been used to create a robust and efficient virtual twin model of a canted cosine theta dipole structure, leveraging the electromagnetic simulation tools CST Studio Suite® and Opera®, the structural solvers available on the 3DEXPERIENCE Platform, and the embedded optimization functionalities. All of the physics simulation and optimization processes share a single parametrized CAD geometry, which provides the flexibility for model design variation and rapid prototyping.

New generation X-ray free electron lasers require reliable and precise synchronization of pulsed laser sources across various locations. This demands stable timing distribution to preserve ultra-low timing jitter, ultrashort pulse duration, and high peak power*. Fiber optic delivery, compared to free-space optics, offers advantages in flexibility, laser safety, ease of deployment and superior output beam quality. However, standard fibers with silica glass core face challenges like high dispersion, nonlinear pulse shaping and environmental sensitivity, causing excess timing jitter. Emerging anti-resonant hollow core fibers that guide light though a central hole have significantly lower environmental sensitivity, high nonlinearity threshold and low dispersion, while achieving attenuation similar to glass-core fibers**. This makes them an improved medium for low-noise transmission of fs pulses with high peak powers. Here, we experimentally demonstrate passively stable timing distribution of femtosecond pulses at 1030-nm center wavelength using sealed hollow core fibers with-out vacuum components. We have achieved a timing precision of 0.3 fs RMS from 1 Hz to 1 MHz and < 250 fs peak-to-peak for 12 hours with a hollow core fiber length of 72 m without requiring any transmission delay stabilization.

Anomalous magnetic moment (g-2) of a muon has been precisely measured by the BNL and FNAL experiments, and there is a discrepancy from the Standard Model prediction. A new measurement of muon g-2 is planned at J-PARC based on a different strategy. In the J-PARC experiment, a low emittance 300 MeV muon beam is injected into a compact storage orbit by newly developed 3-D spiral injection scheme*. Injected muons follow a vertical betatron oscillation around the storage orbit. A reduction of betatron oscillation amplitude is a key to achieve the physics goal of this experiment. This paper presents a new beam profile monitor which measures vertical distribution of stored muons to realize the 3-D spiral injection and to minimize vertical oscillation amplitude. There is a stringent requirement on the effective material budget in order to suppress multiple scattering of muon beam which passes through this monitor for hundred times on every cyclotron period. To achieve this, the monitor utilizes thin scintillating fibers of 0.2 mm diameter are placed with an interval of 10 mm. Reconstruction procedure of vertical beam motion from measured hit distribution will also be discussed.

The next generation of light sources aim to provide bunch beams with small transverse emittances. A common feature in the design of light sources with small emittance lattices is the small value of the momentum compaction, which implies a short nominal equilibrium bunch length. Combined with the small transverse emittances, a short bunch length can pose severe limitations on the beam lifetime caused by collective effects such as intra-beam and Touschek scattering. To improve the beam lifetime of the bunches, an efficient way is to use a Higher-Harmonic Cavity (HHC) system, which leads to an increase of the equilibrium bunch length without an increase of the energy spread. Besides the improvement of beam lifetime, the HHC system plays an important role to cure beam instabilities and mitigate possible beam induced heating issues of the storage ring vacuum components. Present HHC systems are based on HHCs of the same order. To increase the bunch lengthening factor induced by the HHC system, we investigate a novel scheme based on the combination of HHCs of different order. The feasibility and performance of the novel scheme will be studied with the beam dynamics codes SPACE and Elegant, with parameters of the NSLS-II upgrade.

The AGS Booster synchrotron at Brookhaven National Laboratory delivers resonant slow extracted beams to a fixed target beamline called the NASA Space Radiation Laboratory (NSRL). Experimenters at the NSRL require uniformly distributed radiation fields over large area to simulate the cosmic ray space radiation environment. The facility generates the uniform distribution using a pair of octupole magnets in the transport line. The beamline is designed to produce a achromatic optics through the octupoles and to the target. However, the dispersion function depends on the trajectory of the beam as it is transported out of the booster and into the NSRL beamline. The dependence on this trajectory has not been previously studied. In this paper, we describe a new model we have developed to study this effect and show measurements to compare to our simulations.

In a circular collider, precise control of the linear optics in the vicinity of the interaction points plays a crucial role in ensuring optimal operational performance and satisfying the machine protection constraints. Superconducting magnets are affected by unavoidable field errors that impact machine performance, and mitigation strategies are usually put in place to improve the situation. Past studies performed on the LHC have shown the benefit of magnet sorting on both initial beta-beating, through compensation of magnetic field errors, and overall correction quality of the machine optics. This work aims at extending those studies in the context of the luminosity upgrade of the LHC by considering the possible impact on performance from various sorting strategies applied to the new triplet quadrupoles for the ATLAS and CMS high-luminosity insertions.

SIRIUS, a brazilian 4th generation synchrotron light source, currently operates in top-up mode at 100mA in uniform fill. The main limiting factor for reaching higher currents is the temporary RF system in use. It is comprised of one PETRA 7-Cell cavity and two solid state amplifier towers that combined provide at most 120kW of power. By mid 2024, two superconducting RF cavities will replace the current cavity and two amplifier towers will be added to the system, allowing operation at higher currents. The design current of SIRIUS storage ring is 350mA, which can only be achieved once a third harmonic cavity is installed to lengthen the bunches to avoid excessive wake-induced heating of sensitive components. However, the installation of such cavity is not foreseen in the near future, which raises the question of which is the maximum current in uniform fill SIRIUS can be operated. This work will present some theoretical and experimental studies carried out to answer this question.

The transverse narrow-band impedance makes a major contribution to the transverse coupled-bunch instability, which may deteriorate the beam quality in multi-bunch, high-intensity circular accelerators. Thus, strict restriction on the transverse narrow-band impedance are implemented during the initial accelerator design phase. However, slight component structure deviations during the construction of accelerators and component modifications during the subsequent operation may lead to impedance difference from the design value. It is therefore more meaningful to obtain the impedance parameters of circular accelerators by beam experimental measurement during the machine operation. In this paper, by mode distribution of coupled-bunch instability and its growth rate, a method was proposed to obtain the transverse narrow-band impedance which is represented with an LRC resonator. In order to verify the effectiveness of the method, the numerical calculation with three known LRC resonators was used to check their difference and the fitted LRC resonator parameters are in good agreement with the setting values.

We are commissioning a 2.5~MeV proton beam for the Integrable Optics Test Accelerator at Fermilab, allowing experiments in the strong space-charge regime with incoherent betatron tune shifts nearing 0.5. Accurate modelling of space-charge dynamics is vital for understanding planned experiments. We compare anticipated emittance growth and beam loss in the bare IOTA configuration using transverse space-charge models in Xsuite, PyORBIT, and MAD-X simulation codes. Our findings reveal agreement within a factor of 2 in core phase-space density predictions up to 100 synchrotron periods at moderate beam currents, while tail distributions and beam loss show significant differences.

The electron lens for space charge compensation is an R&D project to increase the primary beam intensity and thus the accelerator efficiency of SIS18 and eventually SIS100 for FAIR operation. As a first step, the principle of space charge compensation will be demonstrated in SIS18 with a single lens, aiming at a tune shift of 0.1 for several ion species. However, the design should also be compatible with the SIS100. Following the conceptual design studies, a technical design of the electron lens has been prepared and the main components of the electron lens are currently under development. This contribution gives an overview of the development of the electron lens, with particular emphasis on the main lens components and the studies carried out on the dynamics of the ion beam.

The Spallation Neutron Source (SNS) Beam Test Facility (BTF) supports the study of beam dynamics in the front end of a high power LINAC. The BTF combines a replica of the SNS front end, including nearly-identical ion source, RFQ and MEBT, with extensive phase space diagnostics and a FODO transport line. Diagnostic capabilities include direct measurement of 6D phase space distribution and detection of halo distributions to a sensitivity of greater than one part-per-million. The goal of on-going BTF studies is to demonstrate accurate particle-in-cell modeling of halo growth and evolution by leveraging unprecedented accuracy in the description of the initial beam distribution. This work is motivated by operational experience at the SNS, which currently operates with beam loss that cannot be described by any model. This paper summarizes progress in the BTF beam study program as well as diagnostics development and recent upgrades to the beamline configuration.

The slice model is the theoretical foundation for various beam-beam simulation methods. In the formulation of the slice model, some approximations have been made based on the assumption of particle beams with an extremely high Lorentz factor. However, this assumption might not always be valid for the particle colliders applied in the nuclear physics study because of the usage of heavy-ion beams. It is thus worthwhile to verify the slice model in that parameter regime. In this study, we investigate the theoretical formulations of the slice model and a full 3D model. Besides, we perform weak-strong simulations based on these two theoretical models. Results and their implications will be presented.

Recent experimental measurements in the Large Hadron Collider (LHC) have shown a clear correlation between beam-beam resonance driving terms and beam losses, with a characteristic bunch-by-bunch signature. This observation creates interesting conditions to study diffusive processes. Over the past few decades, early chaos indicators, frequency map analysis and dynamic aperture studies have been commonly used to study particle stability in circular machines. However, the underlying mechanisms driving particles to large amplitudes in the presence of high order resonances is still an open question. Leveraging on years of development on particle tracking tools, this paper presents full-fledged 6-dimensional bunch-by-bunch beam loss simulations in the LHC. The computed loss rates are shown to be in agreement with experimental observations from LHC Run 3.

An advanced online monitoring system with dual systems is being developing for Hefei Advanced Light Facility (HALF). One is based on the C language, which integrates data acquisition, storage and interface display. The other is based on EPICS system, which developed Input/Output Controller (IOC) and Operator Interface (OPI) for data acquisition and display. The two systems are based on Ethernet TCP / IP protocol for data communication, but they are independent. The on-line radiation monitoring system of Hefei Advanced Light Source (ORMSH) have the function of neutron and gamma dose monitoring and alarming. The ORMSH contains 160 monitors for workplace monitoring and environmental monitoring. Each monitor combines data collection, storage, automatic upload. two alarm methods will be adopted for dose interlocking in ORMSH: instantaneous dose rate alarming and cumulative dose alarming. This paper describes in detail the implementation of the system infrastructure and functions.

The Hefei Advanced Light Facility (HALF) is a diffraction-limited storage ring-based light source consists of a 180 m linear accelerator and a 480 m storage ring. The RF reference signal included 499.8 MHz and 2856 MHz are generated from two phase-locked master oscillators and transmitted to the RF system, beam position monitor system, timing system and beamline station by the phase stabled coaxial cables which are installed in the ±0.1℃ thermostatic bath. The RF Reference Distribution System (RF-RDS) are developed to realize the phase synchronization and transmission with low phase noise for long distance. The continues wave amplifier is manufactured to generate RF power of 10 W, with the added phase noise being less than 1 fs (10 Hz~10 MHz). The phase noise of each receiving terminal is estimated to be less than 30 fs (10 Hz~10 MHz). The design of RF-RDS and experimental result are discussed in this paper.

We present a method for coupling particle dynamics, particle-matter interaction, and hydrodynamics codes to model the effects of high-intensity electron beams in Fourth Generation Storage Rings for the purpose of machine protection. The coupled codes determine if high-energy-density conditions (>100 J/mm^3) are present in beam-intercepting components. Elegant is used to simulate the dynamics of a whole-beam abort by muting the high-power cavity RF. Within the APS-U, the impacting beam begins interacting with a horizontal collimator, at which point elegant is interrupted and the beam impact process is modeled using MARS and FLASH. MARS simulates the interaction of the beam with the collimator, passes the energy density to FLASH, and returns the transmitted particle distribution to elegant. FLASH uses the energy deposition to determine the density of the collimator material. The surviving beam is propagated again through the APS-U lattice and the process is repeated until the beam is fully lost. The input MARS geometry is updated each step to reflect the changing material properties. The coupled codes also examine the effects of synchrotron radiation within the vacuum beam chambers.

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.

The normal-conducting injector of the superconducting proton linac of the European Spallation Source (ESS) was commissioned in 2023. Commissioning of the superconducting linac is planned by end of 2024, followed by first beam on the spallation target in 2025. One of the prominent challenges in commissioning and operation of high power accelerators, such as the linac of the ESS, is to minimize beam loss to protect its components from excessive activation and potential damage. Sensitivity studies looking at various types of errors were conducted in the past during the design phase for defining requirements and tolerances. With the commissioning of the full linac approaching, a revised error sensitivity study was carried out, and the result is presented in this paper. The aim of the revised study is to better understand the relation between potential error sources and loss patterns.

In recent years, mixed helium and carbon ion irradiation schemes have been proposed to facilitate in-vivo range verification in ion beam therapy. Such a scheme proposes to deliver both ion species simultaneously, with the idea of performing the treatment with carbon ions, while exploiting helium for online dosimetry downstream of the patient. The center for ion beam therapy and research MedAustron supplies protons and carbon ions for clinical treatment. It is currently being commissioned to additionally provide helium ions for non-clinical research, opening the opportunity for exploring the feasibility of mixed beam irradiation. A key aspect in this context is the slow extraction of the ion mix, which is affected by the relative charge-to-mass ratio offset between the two ions of approximately 6e-4. This contribution analyses differences in the transverse phase space and tune distributions of the two ion species and subsequently discusses first simulation results of the extraction process.

We study possibility of laser assisted charge exchange injection at the SNS. The realistic injection of LACE injection and accumulation into the Ring of SNS is considered. The design of stripping magnets at the injection area is one of the most challenging problems toward operational scheme of LACE at the SNS. Basic requirements and needed parameters of stripping magnets are studied. Based on this study the possibility of real stripping magnet design is considered.

The replacement of radionuclides used for cancer therapy with accelerators offers several advantages for both patients and medical staff. These include the elimination of: unwanted dose, specialized storage and transportation, and isotope production/replacement. Several electronic brachytherapy devices exist, and typically utilize an x-ray tube around 50 keV. These have primarily been used for skin cancer, though intraoperative applications are becoming possible. For several types of cancer, Iridium-192 has been the only brachytherapy treatment option, due to its high dose rate and 380 keV average energy. An accelerator-based alternative to Ir-192 has been developed, comprised of a 9.4 GHz, 1 MeV compact brazeless accelerator, narrow drift tube, and target. The accelerator is supported and positioned through the use of a robotic arm, allowing for remote delivery of radiation for internal cancer treatment. Preliminary results including dose rate and profile and plans for complete system demonstration will be presented.

In order to miniaturize ion injectors for particle therapy, a design of ion injectors based on a 325 MHz operating frequency was completed. The LINAC was consist of a 2.0 m length RFQ and a 3.8 m length IH-DTL, which was designed to accelerate 12C4+, 3H+, 3He+ and 18O6+ beams to 7 MeV/u. The RFQ cavity and the first DTL tank was been manufactured using aluminum. This paper gives an overview of the fabrication and tuning procedure of the prototype. The quadrupole electric field of the RFQ is adjusted flat by the tuner while reducing the dipole field components in both directions. The measured DTL electric field distribution after tuning is in good agreement with the simulation results.

In contemporary radiotherapy, most accelerators employ the scatter technique to achieve a relatively uniform dose distribution of electron beams. However, this method often results in the loss of a substantial number of particles, leading to suboptimal efficiency. This paper proposes a method utilizing permanent magnet components to homogenize the beam, achieving both beam spreading and uniformity within a short distance without particle loss. The proposed homogenization beamline comprises two quadrupole magnets and two octupole magnets, ultimately yielding a square field with a side length of approximately 20 cm. The manuscript includes theoretical derivations and simulation validations, with the physical prototype currently under fabrication. Experimental results will be provided in future work.

In this work, MAX FLASH system (Multi-Angle ultrahigh dose rate megavolt-level X-ray radiation system for FLASH radiotherapy) is presented. This system consists of a rapid RF power distribution network and five linacs vertically installed at different coplanar angles. The distribution network can switch all power to one terminal linac between pulses. Electron beams are accelerated to 10 MeV with more than 400 mA peak currents in the high-performance linac and then convert into X-ray at a compact rotating target. The system aims for a compact FLASH radiotherapy clinical facility with a gantry 3 meter in diameter and 2.5 meter in length, which can be installed in most of hospital radiotherapy treatment rooms. There is reserved space in the gantry for a coplanar CBCT to implement for image guidance. The gantry can rotate to an optimized angle for a better conformality before radiation while the system remains stationary and switches the operating linac during radiation. Construction of the first system prototype, with 40 Gy/s dose rate at 80 cm source-axis-distance, is supposed to be finished in the summer of 2024.

By using a high-energy electron beam (beam energy of several hundred MeV) strongly focused on the tumor lesion area, radiotherapy can be performed with a relatively simple beam generation and handling system while resulting in a suitable shape of the deposition energy curve in a tissue-like material. Quadrupole magnets are typically used for beam focusing, which makes the beam delivery system complex and challenging from an engineering point of view. In the Geant4 simulation toolkit, we performed a feasibility study of an alternative solution, in which focusing is achieved by using a bent silicon crystal with an appropriately shaped exit surface. However, the focusing strength is still not high enough. Research to find the optimal crystal shape to achieve the ideal focusing strength is ongoing. Such a crystal lens can be a very light object (mass in the order of grams), allowing for a much simpler beam delivery system for radiotherapy facilities.

An exact solution for the radiation field of a particle in a helical undulator, valid for an arbitrary point in space and an arbitrary particle energy, was obtained by the partial domain method, generalized for the case of spiral motion of a particle. The interface between the regions is a cylindrical surface containing the spiral trajectory of the particle. A comparison is made with the existing solution, which is valid in the far zone at high particle energies.

The High Energy Photon Source (HEPS) is the fourth-generation synchrotron photon source. Compared with the third-generation synchrotron photon source, the brightness is 100-1000 times higher, and the electron emittance of the storage ring is low to the diffraction limit of light. Through physical calculations, it is required that the stability of the storage ring quadrupole magnet power supply be better than 10ppm, and the accuracy of output current be better than 80ppm. This high demand for technical parameter poses a challenge to the development of high precision and stability power supplies. The main circuit topology of the power supply adopts a phase shifted full bridge soft switching scheme, which avoids interference caused by switching noise and improves power stability and efficiency. The high-precision digital power supply controller based on FPGA improves the sampling speed and control accuracy of the power supply, and the constant temperature control circuit ensures that the output current of the power supply meets the requirements of HEPS for power supply performance. In the batch testing section, a testing facility was built to test the stability, accuracy, repeatability, voltage ripple, and other parameter of high precision and stability power supplies. After a year and a half of testing, the performance tests of 1066 power supplies, including linear accelerators power supplies, booster power supplies, storage rings power supplies, dipole and quadrupole combined power supplies, dipole and quadrupole power supplies, were completed. The results all met and exceeded the design specifications. The HEPS high precision and stability power supply meets the design requirements in terms of current stability, accuracy, repeatability, voltage ripple, and other aspects. The batch test results show that the power supply performance using the full bridge phase shifting soft switching technology combined with high-precision digital controller scheme is excellent, and the power supply consistency is good, providing a guarantee for the successful operation of HEPS in the future.

In order to enhance the accelerating gradient of accelerators, cryogenic accelerating structures have been investigated. Based on material characteristics and technical conditions, a fundamental design has been accomplished. Photonic band-gap (PBG) structures employ a lattice of rods to impede the propagation of RF field through the lattice at specific frequencies while effectively damping higher order modes. The design of the single-cell PBG structure has been refined by altering the shape of the rods surrounding the defect region in order to miti-gate peak surface magnetic field within the structure. The combination of PBG cells and a bi-periodic accelerating structure has resulted in the design of a novel structure. This innovative configuration possesses the advantageous characteristics of a bi-periodic structure while incorporating the additional functionality of a PBG struc-ture to effectively damping higher order modes.

Bent crystals are a mature technology used in several applications at CERN, such as the crystal-assisted collimation system for LHC ion operation and reduction of losses during the slow extraction from the SPS by shadowing the electrostatic septum. In the future, it is planned to measure electric and magnetic dipole moments of short-lived particles with a double-crystal experiment in the LHC. To consolidate their strategic use, CERN has been equipped to produce in-house bent crystals. Each crystal is required to be fully validated before its installation by different techniques, such as metrology, X-ray diffractometry and characterization with beams. The latter can measure the bending angle, the torsion, and the channeling efficiency, which is related to crystal imperfections. In this contribution, we present the performance with beams of the first prototype bent crystals manufactured at CERN and tested during a measurement campaign in the North Area.

It has been seven years since the Taiwan Photon Source (TPS) started to serve users in 2016. Sixteen beamlines had been installed in the first and second phases of TPS beamline project. The third phase project was also launched in 2021. Considering the experimental hall is more compact and power saving issue, our research aimed to analyze a modified air conditioning system with better cooling efficiency through Computational Fluid Dynamic (CFD) simulation. One twelfth of the TPS experimental hall and two beamlines are modeled.

In this paper, the widely used RF measurement bead-pull technique for the S-band accelerating structure pre-tuning of the AREAL linear accelerator is presented. Bead-pull measurements were conducted before brazing with various group sets of accelerating cells to evaluate the effectiveness of “smart combinations” for AREAL accelerating structures. The “smart combination” technique represents the grouping of cells with corresponding lengths to achieve the same length sets (triplets for 2π/3 mode) as it is possible. Cell lengths were measured in advance based on TM resonance frequencies measurement. This procedure will significantly reduce the tuning routine required after brazing.

Tokyo Denkai has been producing niobium for superconducting cavities since 1985. We have also produced niobium for L-band cavities since the beginning of their development, and have a large number of production records. In particular, more than 20,000 pieces have been delivered to TESLA based on the XFEL-007 specifications for the European XFEL, LCLS-II, LCLS-II HE, and SHINE projects. In this report, we present a statistical evaluation of measured data on the actual mechanical properties of niobium sheets in a mass production of niobium sheets based on nearly identical specifications. Specifically, histograms of hardness, RRR, and tensile testing (rolling and transverse direction) of niobium sheets were drawn to evaluate the data variability. The data for all items were normally distributed, indicating that quality was controlled. In addition, the relationship between rolling direction and all tensile test items (yield stress, maximum stress, and elongation) were examined. Positive correlations were observed for yield stress and maximum stress. I report on the quality data and statistical results of the same product over a period of more than 10 years.