SUPG
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Student Poster Session: SUPG
19 May 2024, 14:00 -
18:00
Chair: Kiersten Ruisard (Oak Ridge National Laboratory)
SUPG001
Real time crystal collimation monitoring at the CERN Large Hadron Collider
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At the CERN Large Hadron Collider (LHC), bent crystals play a crucial role in efficiently redirecting beam halo particles toward secondary collimators used for absorption. This innovative crystal collimation method leverages millimeter-sized crystals to achieve deflection equivalent to a magnetic field of hundreds of Tesla, significantly enhancing the machine’s cleaning performance particularly when running with heavy ion beams. Nevertheless, ensuring the continuous effectiveness of this process requires the optimal channeling angle with respect to the beam to be constantly maintained. The primary goal of this study is to improve the monitoring of crystal collimation by providing a tool that detects any deviations from the optimal channeling orientation. These deviations can arise from both crystal movement and fluctuations in beam dynamics. The ability to adapt and compensate for these changes is crucial for ensuring stable performance of crystal collimation during LHC operation. To achieve this, a feedforward neural network (FNN) was trained using data collected during the 2023 lead ion physics run at the LHC. The results demonstrate the network’s capability to supervise these crystal devices, accurately classifying when the crystal is optimally aligned with respect to the circulating beam. Furthermore, the model provides valuable insights into how to adjust the crystal’s position to restore optimal channeling conditions when required.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPS42
About: Received: 10 May 2024 — Revised: 19 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
SUPG002
Bayesian optimization scheme for the design of a nanofibrous high power target
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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.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPS45
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
SUPG003
Direct measurements of RHIC BPM data at the IP using linear regression
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Many mature methods to measure the betatron function of a lattice rely on beam position monitor (BPM) data and the model of the whole machine. In this study, specific sections of the Relativistic Heavy Ion Collider (RHIC) were analyzed, taking advantage of BPMs separated by drift spaces near interaction points (IPs) and B3/B4 magnet sections of RHIC. This (local) approach would provide a alternative measure of the linear optics at specific regions which can be compared to previous (global) methods. This process utilizes the phase transfer matrix built from existing BPM data from RHIC using Linear Regression (LR) techniques. Non-AC dipole BPM data as well as AC dipole data was used to measure the linear optics. It was found that the local method yields comparable beta beat to global methods; however, it differs significantly around IP6. This study demonstrates that using LR analysis has advantages and disadvantages, and that further studies are needed to improve the method.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC18
About: Received: 14 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
SUPG004
Advancing non-linear space charge simulations: neural networks and analytical approaches
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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.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS08
About: Received: 15 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
SUPG005
Dynamics study of the crab crossing at the electron ion collider using square matrix and iterative methods
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Crab crossings are designed to increase the luminosity of accelerators by ensuring beam interactions are closer to a head on collision. One will be implemented at the Electron Ion Collider (EIC) at Brookhaven National Laboratory. It is then important to examine how the crab cavity will affect beam dynamics at the EIC. Methods such as Frequency Map Analysis (FMA) have been shown to be helpful in examining the phase space of accelerators in order to find properties such as resonances and the dynamic aperture. An alternative to such methods is an iterative method based on square matrix method that has been shown to reveal similar properties as FMA while reducing the computational power needed*,**. This method has been applied to the crab crossing scheme in order to find and explain effects of the higher order mode of crab cavities on the particle dynamics of the EIC.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS11
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
SUPG006
Optimizing the sextupole configuration for simultaneous correction of third order resonances at the recycler ring
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For the Recycler Ring at Fermilab, space charge tune shifts of almost 0.1 will have to be dealt with under the Proton Improvement Plan (PIP-II) framework. This will lead to the excitation of third order resonances. The minimization of Resonance Driving Terms (RDTs) allows to mitigate the harmful effect of these betatron resonances. Past work has shown that previously-installed sextupoles can compensate the RDTs of individual third order resonance lines, thus reducing particle losses in these operational regimes. Nevertheless, trying to compensate multiple resonances of the same order simultaneously with these existing sextupoles is limited due to current constraints in the magnets. The following study showcases the procedure to install additional sextupoles in order to aid the compensation of multiple resonances. This includes the optimization of the new sextupoles' locations in order to cancel out multiple RDTs while minimizing the currents needed. This is followed by a verification of their effectiveness by means of the RDT response matrix.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS16
About: Received: 16 May 2024 — Revised: 21 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
SUPG007
Tracking study of the bimodal RF cavity for storage ring light source
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Beam lengthening is an effective and commonly used method to improving the beamlife of storage rings. Based on the previously proposed design of a room temperature conducting bimodal RF cavity. we conducted relevant dynamic simulations. Tracking study on a simulated storage ring lattice with the beam energy of 2 GeV and the synchronous radiation energy of 357 KeV, the results show that, the bimodal RF cavity which contains an accelerating field and a third harmonic field can effectively lengthen beam length, the beam lengthening effect similar to the double RF system which consists of main RF cavity and third harmonic cavity.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS19
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
SUPG008
Study and simulation of cryogenic photonic-band-gap disk-loaded structure
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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 structure to effectively damping higher order modes.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPS16
About: Received: 13 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
SUPG009
Comprehensive modeling of Siberian Snakes in BNL’s AGS: symplectic tracking and optical compensation
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Meaningful prediction and enhancement of spin-polarization in the RHIC/EIC accelerator complex relies on accurate modeling of each sub-component. Here we describe a symplectic field approximations of both Siberian Snakes in the AGS, enabling practical long-term tracking calculations. Without such symplectic representations, particle motion destabilizes very quickly close to injection energy. This optical instability manifests in $O(10^3)$ turns, and makes dynamic aperture smaller than realistic emittances. Combined with optimization using the Bmad toolkit, we implement steering and optical corrections of the snake effects at 80 distinct energies from injection to extraction, mimicking the measured lattice conditions at each energy. This process unveils unforeseen snake distortions of the vertical dispersion near injection energy, which are addressed. By interpolating between such optimized lattice configurations, Bmad's tracking capabilities allow advanced simulation of polarization transmission through the full AGS cycle.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS03
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
SUPG010
A wireless method for beam coupling impedance bench measurement of resonant structures
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The Beam Coupling Impedance (BCI) is a crucial aspect in the realm of accelerator physics, as it describes the electromagnetic interactions between charged particle beams and the accelerator structure. The measurement and quantification of BCI is an essential requirement to assess and mitigate its impact, particularly when introducing new components or addressing problems within existing devices. The stretched Wire Method (WM) is a well-established technique for BCI evaluations, although with well-known limitations. These are particularly prominent when dealing with cavity-like structures. In that case, the estimates obtained below the cut-off frequency of the beam pipe can be inaccurate. It is worth noting that this frequency range is particularly relevant for many accelerator applications. To overcome these well-recognized limitations, a different bench measurement technique has been identified and thoroughly examined. This novel approach has been subjected to comprehensive testing in both virtual and real measurements, with a particular focus on a pillbox cavity.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC53
About: Received: 10 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
SUPG011
Simulation of beam loading compensation with RF-Track
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The beam loading effect results in a gradient reduction of the accelerating structures due to the excitation of the fundamental mode when the beam travels through the cavity. A recent implementation of this process in the tracking code RF-Track allows the simulation of realistic scenarios, thus revealing the impact of this phenomenon in start-to-end accelerator designs. In this paper, we present the latest update of the beam loading module which allows the simulation of the compensation of this effect and we explore the potential of the developed tool in heavy-loaded scenarios.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC56
About: Received: 14 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
SUPG013
Emittance growth studies due to Crab Cavity induced amplitude noise in the SPS
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In the context of the HL-LHC upgrade, RF Crab Cavities (CCs) are one of the key components. Due to the increased intensity, the collider will operate with a large crossing angle scheme and these CCs will be used to counteract the geometrical reduction factor coming from the crossing angle. Amplitude and phase noise injected from the Low-Level RF, are known to induce transverse bunch emittance growth. This contribution presents the latest measurements of emittance growth induced by amplitude noise. The measurement was performed thanks to the SPS Beam Synchrotron Radiation Telescope (BSRT), that has been used to characterize the evolution of the transverse distributions. The measured emittance growth was found to be dependent on the amplitude detuning induced by the SPS octupoles, although no dependence was predicted by the available theories and models. In this paper, the measurement results will be presented and discussed.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC63
About: Received: 06 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
SUPG014
Slow longitudinal mode 1 instability in electron storage rings with harmonic cavities
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Recent studies have investigated a longitudinal instability that may develop in electron storage rings featuring higher-harmonic cavities. The instability, also referred to as periodic transient beam loading (PTBL), manifests as a slow oscillation of bunch longitudinal profiles following a coupled-bunch mode 1 pattern. In this contribution, we applied a well-established theory of longitudinal mode-coupling to assess the thresholds for this instability. Results obtained through this semi-analytical approach, considering different storage ring and harmonic cavity parameters, were validated using macroparticle tracking and compared against other methods proposed in previous investigations.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS32
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
SUPG015
Unifying coherent synchrotron radiation wakefield and classical radiation reaction
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We develop an alternative theory of coherent synchrotron radiation (CSR) wakefield using the transverse field solution of Maxwell equations in angular domain. This approach allows us to retain only the radiative interaction between particles and cure the frequently encountered divergence in retarded potentials. We analyze the classical radiation reaction force and mass renormalization induced by the CSR self-field. Futhermore, we illustrate our theory by explicitly calculating the steady-state CSR wakefield of a wiggler.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS47
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
SUPG016
Measurement of stability diagrams in the IOTA ring at Fermilab
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Nonlinear focusing elements can enhance the stability of particle beams in high-energy colliders through Landau Damping, by means of the tune spread which is introduced. Here we discuss an experiment at Fermilab's Integrable Optics Test Accelerator (IOTA) which investigates the influence of nonlinear focusing elements, such as octupoles, on the beam’s transverse stability. In this experiment, we employ an anti-damper, an active transverse feedback system, as a controlled mechanism to induce coherent beam instability. By utilizing the anti-damper we can examine the impact of a nonlinear focusing element on the beam's transverse stability. The stability diagram, a tool used to determine the system's stability, is measured using a recently demonstrated method at the LHC. The experiment at IOTA adds insight towards this stability diagram measurement method by supplying a reduced machine impedance to investigate the machine impedance’s effect on the stability diagram, as well as by aiming to map out the full stability diagram by using a large phase range of the anti-damper. From this experiment in IOTA, we present the first results of stability diagram analysis with varying octupole currents.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPR48
About: Received: 20 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
SUPG017
Near-infrared noise in intense electron beams
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Requirements for the noise in electron beams (NEB) have recently approached the Shot-noise level in some new applications. The density fluctuations of intense beams in the near-infrared (NIR) region are being measured at the Fermilab Accelerator Science and Technology (FAST) facility. The main goal of the experiment is to accurately compare the Shot-noise model with the observations of optical transition radiation (OTR) generated by the gamma=63 electron beam transiting an Al metal surface. In addition, evidence for longitudinal-space-charge-induced microbunching for the chicane-compressed beam was obtained with coherent enhancements up to 100 in the various bandwidth-filtered NIR OTR photodiode signals. With micropulse charges up to 1 nC, the beam parameters are close to those proposed for a stage in an Electron-Ion Collider (EIC) with coherent electron cooling (CEC). In this paper we present the current progress of the NEB project and compare the low electron energy measurements with ImpactX simulations.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPR49
About: Received: 15 May 2024 — Revised: 18 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
SUPG018
Minimizing space charge tune spread and increasing beam quality parameters with circular modes
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Space charge has been a limiting effect for low energy accelerators inducing emittance growth and tune spread. Tune shift and tune spread parameters are important for avoiding resonances, which limits intensity of the beam. Circular modes are round beams with intrinsic flatness that are generated through strong coupling, where intrinsic flatness can be transformed to real plane flatness through decoupling. It is understood that flat beams increase the quality parameters of a beam due to one of the plane emittances being smaller than the other plane since luminosity and beam brightness depend inversely on the beam emittances. We show that circular mode beams manifest smaller space charge tune spread compared to uncorrelated round beams, which allows better systematic control of operating point of the beam. Minimized tune spread allows flexible operating points on the tune map. We also dedicate current and intrinsic flatness ratio limits on circular modes, which increase quality parameters without detrimental effects on the emittance increase.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC71
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
SUPG019
Measurement and modeling of beam transport in the FODO line of the Spallation Neutron Source Beam Test Facility
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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.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUAN2
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
SUPG020
Simulation studies of laser cooling for the Gamma Factory proof-of-principle experiment at the CERN SPS
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The proof-of-principle (PoP) experiment at the Super Proton Synchrotron (SPS) at CERN aims at demonstrating laser cooling of high energy Li-like Pb79+ in a synchrotron. First laser cooling simulations with realistic laser and beam parameters of the Gamma Factory proof-of-principle experiment (PoP) in the Super Proton Synchrotron (SPS) at CERN are presented. Furthermore, we investigate the expected cooling performance for various laser-pulse types, such as Fourier-limited and continuous wave lasers, and compare their performance metrics such as emittance reduction and the required laser power.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS50
About: Received: 15 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
SUPG021
Proposal for a proton-bunch compression experiment at IOTA in the strong space-charge regime
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The longitudinal compression of intense proton bunches with strong space-charge force is an essential component of a proton-based muon source for a muon collider. This paper discusses a proton-bunch compression experiment at the Integrable Optics Test Accelerator (IOTA) storage ring at Fermilab to explore optimal radio frequency (RF) cavity and lattice configurations. IOTA is a compact fixed-energy storage ring that can circulate a 2.5-MeV proton beam with varying beam parameters and lattice configurations. The study will aim to demonstrate a bunch-compression factor of at least 2 in the IOTA ring while examining the impact of intense space-charge effects on the compression process.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS57
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
SUPG022
Generation of attosecond electron bunches through terahertz regulation
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Obtaining ultrashort electron bunches is the key to the studies of ultrafast science, yet second and higher order nonlinearities limits the bunch length to a few femtoseconds after compression. Traditional regulation methods using rf higher order harmonics have already optimized the bunch length to sub-fs scale, yet the energy loss and rf jitter are not negligible. In this paper we demonstrate the second order regulation with THz pulses through a dielectric-loaded wave-guide. Simulations suggest that with higher order correction, the MeV electron bunches with tens of fC charges can be compressed to a 679 attoseconds rms and the second order distortion can be compensated. The transverse beam size is also optimized to 16.8 um rms. This scheme is feasible for a wide range of electron charges. The relatively short bunch length is expected to find a better time resolution in UED, UEM and other ultrafast, time-resolved studies.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS62
About: Received: 11 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
SUPG023
Research on spatial alignment of laser and electron beam in the generation of ultra-short electron pulses by laser modulation
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The utilization of laser modulation techniques shows potential in producing sub-femtosecond electron beams within photoinjector electron guns. The precise spatial alignment between the modulated laser and electron beam is crucial for the stable emission of sub-femtosecond electron beams. In practical applications, inevitable lateral positional fluctuations are present in both the modulated laser and electron beam pulses, resulting in uneven and suboptimal modulation effects of the laser on the electron beam. Photocathode electron guns commonly utilize solenoid focusing for transverse electron beam concentration, inducing transverse phase space coupling and causing the laser-induced transverse jitter in the electron gun to not accurately reflect the transverse jitter of the electron beam. This study seeks to employ coherent lasers and devise a solenoid coil to disentangle the transverse phase space of the electron beam, ensuring that the transverse jitter of the electron beam aligns with the jitter of the modulated laser at the focal point.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS63
About: Received: 10 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
SUPG024
Comparison of WarpX and GUINEA-PIG for electron positron collisions
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As part of the Snowmass'21 planning exercise, the Advanced Accelerator Concepts community proposed developing multi-TeV linear colliders and considered beam-beam effects for these machines [1]. Such colliders operate under a high disruption regime with an enormous number of electron-positron pairs produced from QED effects. Thus, it requires a self-consistent treatment of the fields produced by the pairs, which is not implemented in state-of-the-art beam-beam codes such as GUINEA-PIG. WarpX is a parallel, open-source, and portable particle-in-cell code with an active developer community that models QED processes with photon and pair generation in relativistic laser-beam interactions [2]. However, its application to beam-beam collisions has yet to be fully explored. In this work, we benchmark the luminosity spectra, photon spectra, and the recently implemented pair production processes from WarpX against GUINEA-PIG in ultra-tight collisions, and ILC scenarios. This is followed by a run-time comparison to demonstrate the speed-up advantage of WarpX. Ultimately, this work ensures a more robust modeling approach to electron-positron collisions, with the goal of scaling up to 15 TeV.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC84
About: Received: 14 May 2024 — Revised: 16 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
SUPG025
Bunch-by-bunch simulations of beam-beam driven particle losses in the LHC
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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.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC80
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
SUPG026
Study of the beam-beam interaction in an electron-positron collider with large Piwinski angle and crabbed waist
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To achieve very high luminosity, the next generation circular colliders adopt the crab waist collision scheme with a large Piwinski angle. In this scheme, beams collide with high current, low emittances, and small beta functions at the interaction point (IP). However, several effects arising from these extreme parameters, especially the coherent X-Z instability, will significantly impact the collider's performance, necessitating dynamic processing of longitudinal motion in a three-dimensional self-consistent treatment. The transverse vibration becomes coupled with the longitudinal motion, as well as the increase in horizontal beam size alters the interaction between beams and corresponding beam-induced effects. These instabilities limit the stable high luminosity area for the selected working point of the original design. Therefore, it is necessary to optimize the safe area of the working point by readjusting the parameters of the IP.In this paper, based on the Super Tau-Charm Facility (STCF) project in China, the instability caused by beam interactions is studied through numerical simulation. The relationship between the parameters at the IP and the stable selection area of the working point is systematically explored. The regularities found from simulations can assist future high luminosity electron-positron colliders in selecting the corresponding parameters. Additionally, some methods, such as adding adjustable devices to achieve stable high luminosity, are also proposed.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC81
About: Received: 12 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
SUPG027
3D beam tracking studies including intrabeam scattering
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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.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPR62
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
SUPG028
Development of novel magnetically-focussed minibeams for in vivo and in vitro end stations for Laser-hybrid Accelerator for Radiobiological Applications
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Radiotherapy is an effective, non-invasive, widely used treatment for cancerous tumours that uses x-ray photon, electron and ion beam sources. The Laser-hybrid Accelerator for Radiobiological Applications (LhARA) is a novel laser-driven accelerator system under development that aims to prove the principle of the laser-driven approach to Particle Beam Therapy (PBT). This study aims at the development of a novel system to deliver different light ion minibeams to the in vivo and in vitro end stations. The desired minibeams will be delivered by magnetically focusing and steering the incoming proton and light ion beams, without the use of collimators. Minibeams with a diameter of approximately 1 mm spot will be delivered at an energy of 15 MeV to the in vivo and in vitro end stations. An update on the status of the development of this magnetic focusing technique will be presented here.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPR63
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
Field emission assisted heating of Cs2Te photocathode: implication toward RF breakdown
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The occurrence of breakdown events are a primary limiting factor for future accelerator applications aiming to operate under high field-gradient environments. Experimental evidence often leads to a hypothesis that breakdown events are associated with temperature and dark current spikes on the surface of RF devices. In the past decade, there has been increased interest in unveiling the mechanism behind breakdown in metal copper and copper alloys; however, there has been a limited effort regarding breakdown phenomenon in photocathode relevant semiconductors. In this work, we explore field emission assisted localized heating via Nottingham and Joule processes. Field emission from intrinsic cesium telluride ultra thin film coated on top of a copper substrate was modeled within Stratton–Baskin–Lvov–Fursey formalism, describing the processes and effects in the bulk and at the surface of a semiconductor exposed to a high applied electric field. These heating effects were incorporated into the surface diffusion model, where the surface gradient of the chemical potential defines the time evolution and resulting reorganization of the surface.
SUPG031
Modeling and optimization of the FACET-II injector with machine learning algorithms
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Linear particle accelerators are elaborate machines that demand a thorough comprehension of their beam physics interactions to enhance performance. Traditionally, physics simulations model the physics interactions inside a machine but they are computationally intensive. A novel solution to the long runtimes of physics simulations is replacing the intensive computations with a machine learning model that predicts the results instead of simulating them. Simple neural networks take milliseconds to compute the results. The ability to make physics predictions in almost real time opens a world of online models that can predict diagnostics which typically are destructive to the beam when measured. This research entailed the incorporation of an innovative simulation infrastructure for the SLAC FACET-II group, aimed at optimizing existing physics simulations through advanced algorithms. The new infrastructure saves the simulation data at each step in optimization and then improves the input parameters to achieve a more desired result. The data generated by the simulation was then used to create a machine learning model to predict the parameters generated in the simulation. The machine learning model was a simple feedforward neural network and showed success in accurately predicting parameters such as beam emittance and bunch length from varied inputs.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS79
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
SUPG032
Discovering transient models of emittance growth via mode interaction of phase space nonuniformities
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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.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS82
About: Received: 22 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
SUPG033
Bayesian optimization for beam centroid correction at ISAC
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Beam tuning in a post-accelerator facility such as TRIUMF’s ISAC involves a considerable amount of overhead and often leads to tunes which diverge from the theoretical optimum for the system, introducing undesirable effects such as aberrations or chromatic couplings. Bayesian Optimization for Ion Steering (BOIS) has been developed and tested to perform centroid corrective steering, after the transverse optics have been set to theory, in a method which is fully online and easy to deploy. Naïve multi-objective adaptations, scaleBOIS and boundBOIS have been introduced to perform corrective transverse steering with minimal transverse fields . Tests in the low-energy electrostatic transport beamlines at ISAC I performed comparably to human operators. This work holds promise for enhancing the efficiency and reliability of beam delivery via autonomous tuning methods, supporting TRIUMF's scientific mission.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPS54
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
SUPG034
SRF cavity fault prediction using deep learning at Jefferson Lab
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In this study, we present a deep learning-based pipeline for predicting superconducting radio-frequency (SRF) cavity faults in the Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab. We leverage pre-fault RF signals from C100-type cavities and employ deep learning to predict faults in advance of their onset. We train a binary classifier model to distinguish between stable and impending fault signals, where each cryomodule has a uniquely trained model. Test results show accuracies exceeding 99% in each of the six models for distinguishing between normal signals and pre-fault signals from a class of more slowly developing fault types, such as microphonics-induced faults. We describe results from a proof-of-principle demonstration on a realistic, imbalanced data set and report performance metrics. Encouraging results suggest that future SRF systems could leverage this framework and implement measures to mitigate the onset in more slowly developing fault types.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPS68
About: Received: 02 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
SUPG035
SRF cavity instability detection with machine learning at CEBAF
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During the operation of the Continuous Electron Beam Accelerator Facility (CEBAF), one or more unstable superconducting radio-frequency (SRF) cavities often cause beam loss trips while the unstable cavities themselves do not necessarily trip off. The present RF controls for the legacy cavities report at only 1 Hz, which is too slow to detect fast transient instabilities during these trip events. These challenges make the identification of an unstable cavity out of the hundreds installed at CEBAF a difficult and time-consuming task. To tackle these issues, a fast data acquisition system (DAQ) for the legacy SRF cavities has been developed, which records the sample at 5 kHz. A Principal Component Analysis (PCA) approach is being developed to identify anomalous SRF cavity behavior. We will discuss the present status of the DAQ system and PCA model, along with initial performance metrics. Overall, our method offers a practical solution for identifying unstable SRF cavities, contributing to increased beam availability and facility reliability.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPS69
About: Received: 13 May 2024 — Revised: 16 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
SUPG036
Detailed simulation study of wakefield induced beam dynamics in the dielectric dechirper at CLARA
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Minimizing the energy spread within the electron bunch is essential for an optimal performance of free electron lasers. Wakefields from corrugated and dielectric structures have been demonstrated to be effective in bunch dechirping. However, the repercussions in beam quality are not yet well understood. Here, a dielectric wakefield structure, manufactured to be included at the CLARA facility, has been studied by simulations. It consists of two planar and orthogonally oriented dielectric waveguides with adjustable dielectric gaps. This structure allows the longitudinal wakefield to compensate the energy spread while controlling the undesirable effect of the transverse wakefields in the beam quality. Simulations have been performed using the in-house developed code called DiWaCAT. These simulations included different bunch lengths, beam energy spreads and dielectric gaps to allow a better understanding of longitudinal and transverse wakefields beam effects within the dechirper.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG14
About: Received: 10 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
SUPG037
Investigating X-ray detector systems using Monte Carlo techniques
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Digital Tomosynthesis (DT) is a 3D mode of x-ray imaging. Adaptix Ltd have developed a novel mobile DT device enabled by implementing an array of R-ray emission points and a flat-panel detector. This device gives access to human and animal 3D imaging, as well as to non-destructive material evaluation. DT is not as clinically popular as Computed Tomography (CT) or radiography, and flat-panel source DT even less so, thus creating scope to investigate the optimal flat-panel detector technology for this modality. Geant4, a Monte Carlo Particle Transport code, has been used to simulate the Adaptix Ltd system to do this. Parameters such as the material composition of the detectors, the exact detection method and the inclusion vs exclusion of a scintillation layer are tested in this simulation environment. This work aims to find the optimal flat-panel detector design by comparing different scintillator compositions and structures for this DT method. Therefore, the ideal detector that preserves the advantages of this low-cost, low-dose scanning approach is determined.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPR47
About: Received: 14 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
SUPG038
Magnetron diagnostics with a novel optical fibre-Cherenkov detector
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Development of an optical fiber-based beam loss monitor (OBLM) is in progress at the Cockcroft Institute (CI), UK. The novel sensor utilizes the Cherenkov radiation (CR) emitted in optical fibers by relativistic particle showers generated in beam loss or breakdown events. Breakdowns are a problem for high-power magnetrons, such as those in medical accelerator facilities, as damage to the magnetron cathode reduces the device efficiency and lifetime. These events can be detected by emitted CR channeled along the fibers to photomultiplier detectors, and a time-of-flight method can be used to calculate the breakdown location from the CR arrival time. This has previously been demonstrated with the OBLM system on RF cavities (at CLARA, Daresbury Laboratory, and CTF3, CERN); and allows for rapid and reliable breakdown detection which is important for damage mitigation. This contribution presents proof-of-concept measurements from OBLM studies into magnetrons at Teledyne e2v, Chelmsford. It also discusses design adjustments made to improve the detector sensitivity and how the performance can be enhanced using the sensor (or similar).
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG16
About: Received: 14 May 2024 — Revised: 20 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
SUPG039
Gas jet-based beam profile monitor for the electron beam test stand at CERN
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A non-invasive bidirectional beam profile monitor using beam-induced fluorescence upon a thin sheet of gas has been developed at the Cockcroft Institute in collaboration with CERN and GSI. This device is particularly suited to the Electron Beam Test Stand, and as such, a bespoke gas injection has been optimized for this specific use-case to provide diagnostics unavailable to conventional scintillator screens. The bidirectionality allows for the observation of beam reflections back along the beam path as a result of a beam dump with non-optimized repeller electrode potential. Furthermore, the heating effects of a high current DC beam are negated by the self-replenishing gas sheet. These benefits make this device ideal for use in the Electron Beam Test Stand. This contribution summarizes the optimization study of the gas jet generation performed with a multi-objective genetic algorithm to meet required screen dimensions whilst maintaining acceptable vacuum levels.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG18
About: Received: 14 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
SUPG040
Experimental study into the invasiveness of a gas jet beam profile monitor for charged particle beams
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A minimally-invasive gas jet in-vivo dosimeter for medical treatment facilities is being developed at the Cockcroft Institute (UK), to provide full online (real time) monitoring with less frequent calibration. The monitor functions via a thin, low-density, gas jet curtain, intersecting with the beam. Online monitoring is crucial for hadron beams where acceptable dose tolerances are narrow, hence the beam should be perturbed only by the minimum amount necessary to acquire a signal. An experiment to determine the level of invasiveness of supersonic gas jet beam profile monitors was undertaken to quantify how much the gas jet perturbs the beam. This was accomplished using a 10 keV electron gun with a maximum current of ~100 μA, available in the DITAlab of the Cockcroft Institute. A scintillator screen and Faraday cup were placed in path of the beam to measure the change in beam size and current respectively. In the future, a simulation study using GEANT4 will be completed with the experimental beam parameters to verify the results. This contribution examines the perturbation experienced by a particle beam from a gas jet beam profile monitor, and quantifies the effect the jet has on the beam size and current.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG19
About: Received: 14 May 2024 — Revised: 24 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
SUPG041
Updates on the Cornell cryo-MTE-meter beamline
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A critical factor in determining the limit of the brightness of an electron beam is the mean transverse energy (MTE) of its source, which describes the spread in transverse momentum of electrons at the moment of emission from the source. To increase beam brightness, there has been much work in growing novel photocathodes with low MTE and high quantum efficiency (QE) near threshold photoemission excitation energies. Therefore, it is important to have a testing platform for accurately measuring the MTE of a cathode over a range of cryogenic temperatures and photoexcitation energies, with self-consistent results across multiple measurement techniques. Here, we will discuss the characterization and operation of the Cornell Cryo-MTE-Meter beamline which aims to fulfill these criteria for a robust photocathode testing platform.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG21
About: Received: 17 May 2024 — Revised: 18 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
SUPG042
Impact of octupoles on the Schottky spectra of bunched beams
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Schottky monitors serve as non-invasive tools for beam diagnostics, providing insights into crucial bunch characteristics such as tune, chromaticity, bunch profile, or synchrotron frequency distribution. However, octupole magnets commonly used in circular storage rings to mitigate instabilities through the Landau damping mechanism, can significantly affect the Schottky spectrum. Due to the amplitude-dependent incoherent tune shift of individual particles, the satellites of the Schottky spectrum are smeared out as the octupolar field increases. This study investigates the impact of octupoles and their incorporation into theory, with the goal of improving beam and machine parameter evaluation from measured spectra. Theoretical findings are validated through macro-particle simulations conducted across a range of octupole strengths, encompassing typical operational conditions at the Large Hadron Collider.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG32
About: Received: 14 May 2024 — Revised: 20 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
SUPG043
Measuring uniformity and gas density of gas sheet profile monitor for use with heavy-ion accelerators
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We report updates on design work* and ongoing development of a fluorescence-based molecular gas curtain which will be used to observe the 2D transverse profile of multi-charge state heavy ion beams at the Facility for Rare Isotope Beams (FRIB). The device will produce an ultra-thin, rarefied nitrogen gas sheet and requires that the gas curtain be uniform and thin to prevent distortion of the collected signal in operation. To determine the characteristics of the generated curtain, we evaluate the design using a combination of bench-testing with a Bayard-Alpert gauge and molecular dynamics simulations using MolFlow+. This paper details the design and bench testing of the sheet generator, gas removal system, and interaction chamber of the device, as well as expected photon generation from these parameters.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG35
About: Received: 15 May 2024 — Revised: 12 Jun 2024 — Accepted: 12 Jun 2024 — Issue date: 01 Jul 2024
SUPG044
Beam tomography using MCMC
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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 4D reconstruction using Markov Chain Monte Carlo.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG37
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
SUPG045
Design of a 3-cell rectangular deflecting cavity for a compact THz-FEL
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Bunch length is an important parameter for free-electron laser (FEL). The deflecting RF cavity was used in the beam length diagnostic instrument. In this paper, we present the design of a 3-cell rectangular deflecting RF cavity for a compact terahertz (THz) free-electron laser (FEL) facility. The 3-cell deflecting cavity has a residual orbit offset of zero as compared to single-cell deflecting cavity. Rectangular deflecting cavity does not need to lock the dipole polarisation direction as compared to cylindrical cavity. The time resolution of the measurement system can reach 500 fs. In this paper, the cavity design is carried out using CST and the results of cavity analysis are presented. Particle tracking is performed with the Astra code and the space charge effect is taken into account.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG43
About: Received: 14 May 2024 — Revised: 18 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
SUPG046
Beam studies using a Cherenkov diffraction based beam position monitor for AWAKE
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A beam position monitor based on Cherenkov diffraction radiation (ChDR) is being investigated as a way to disentangle the signals generated by the electromagnetic fields of a short-pulse electron bunch from a long proton bunch co-propagating in the AWAKE plasma acceleration experiment at CERN. These ChDR BPMs have undergone renewed testing under a variety of beam conditions with proton and electron bunches in the AWAKE common beamline, at 3 different frequency ranges between 20-110 GHz to quantify the effectiveness of discriminating the electron beam position with and without proton bunches present. These results indicate an increased sensitivity to the electron beam position in the highest frequency bands. Furthermore, high frequency studies investigating the proton bunch spectrum show that a much higher frequency regime is needed to exclude the proton signal than previously expected.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG49
About: Received: 14 May 2024 — Revised: 22 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
SUPG047
Commissioning and experiments with a compact transverse deflecting system at FLUTE
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A Compact Transverse Deflecting System (Compact-TDS) designed for longitudinal electron bunch diagnostics in the femtosecond regime is presently undergoing commissioning at the Karlsruhe Institute of Technology (KIT). This technique, based on THz streaking using a resonator structure, demands a high level of electron beam controllability and stability at the micrometer scale. To meet these requirements, the linear accelerator FLUTE (Ferninfrarot Linac- Und Test-Experiment) has undergone major upgrades in 2023, incorporating a new RF system equipped with a klystron, RF photoinjector and solenoid magnet. In this contribution, we present first experiments conducted with the Compact-TDS at FLUTE, utilizing the upgraded RF setup.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG52
About: Received: 14 May 2024 — Revised: 20 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
SUPG048
Simulations of an electro-optical in-vacuum bunch profile monitor and measurements at KARA for use in the FCC-ee
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The Karlsruhe Research Accelerator (KARA) is an electron storage ring for accelerator research and the synchrotron of the KIT light source at the Karlsruhe Institute of Technology (KIT). KARA features an electro-optical (EO) in-vacuum bunch profile monitor to measure the longitudinal bunch profile in single shot on a turn-by-turn basis using electro-optical spectral decoding (EOSD). A simulation procedure has been set up to evaluate its suitability as a beam instrumentation for the operation of the future electron-position collider FCC-ee. In order to assess the simulations, this contribution focuses on a comparison to EO sampling (EOS) measurements at KARA and a study on the heat load of the EO crystal due to the expected high bunch repetition rate envisioned for FCC-ee.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG56
About: Received: 15 May 2024 — Revised: 18 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
SUPG049
Implementing bunch-by-bunch diagnostics at the KARA booster synchrotron
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In the upcoming compact STorage ring for Accelerator Research and Technology (cSTART), LPA-like electron bunches are only stored for about 100 ms, in which the equilibrium emittance will not be reached. Therefore, to measure parameters such as bunch profiles, arrival times and bunch current losses, bunch-resolved diagnostics are needed. The booster synchrotron of the KARA accelerator accepts pre-accelerated bunches from a racetrack microtron and accelerates them further over a 500 ms long energy ramp. As the KARA booster synchrotron has a similar circumference and injection energy as the cSTART storage ring, new bunch-by-bunch diagnostics developed there can be transferred to the cSTART project with minimal effort. Currently the diagnostic system of the booster is not designed for bunch-by-bunch diagnostics, thus after using the booster as a testbed for cSTART, such a system could be used permanently. At the booster synchrotron we use the picosecond sampling system KAPTURE-II to read-out a button beam position monitor and an avalanche photo diode at the synchrotron light port and compare the results with a commercial bunch-by-bunch system.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG59
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
SUPG051
Multi-mode cavity design and characterization
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We present the design and initial characterization of a multi-mode cavity, a novel electromagnetic structure with potential benefits such as compactness, efficiency, and cost reduction. The 2nd Harmonic mode was chosen to linearize the fundamental mode for use as an accelerating and bunching cavity. The reduction in the number of cavities required to bunch and accelerate promises cost and space savings over conventional approaches. Superfish and COMSOL simulations were used to optimize the cavity's geometry with the goal of balancing various design parameters, such as quality factor (Q-factor), harmonic modes, and mode coupling. A 3D-printed copper-plated cavity was used to validate code predictions. The cavity's multi-mode nature positions it for use with other harmonic modes with small deviations in design. For example, a 3rd Harmonic can be used to decrease energy spread by widening the peak of the fundamental. This research lays the foundation for further exploration of the cavity's applications and optimization for specific use cases, with potential implications for a wide range of accelerator fields.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOCD2
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
Two slit emittance measurement with thermal emittance isolation for an SRF injector
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This study focuses on the beam source for the LCLS-II-HE Low Emittance Injector (LEI) design: a state-of-the-art superconducting radiofrequency (SRF) gun. The LEI is intended to enable extending the LCLS-II-HE’s useful photon energy to 20 keV without additional cryomodules. We consider a robust two-slit emittance measurement optimized for the LEI SRF gun, compatible with the current LEI gun-to-linac beamline design, and extensible to measuring photocathode mean transverse energy (MTE) with the cathode at or below 4 K. In-situ measurement of photocathode MTE, and evolution thereof, could help optimize the overall performance of the LEI. A two-slit method enables determination of the detailed phase-space distribution of the electron bunch, beyond the normal Twiss parameters and emittance provided by methods such as solenoid scans. Additionally, we investigate the RF emittance by recessing the cathode. This allows us to study the influence of the RF field on the bunch phase space. In summary, our work introduces a cutting-edge two-slit emittance measurement methodology that combines different emittance-dampening techniques to isolate intrinsic emittance from the photocathode. Detailed results will be presented at the workshop to highlight established trends, dependencies, and a summary/concept of the future photocathode characterization beamline implementation.
SUPG053
Optimizing current density measurements for intense low beta electron beams
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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.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG63
About: Received: 15 May 2024 — Revised: 23 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
SUPG054
SiPM integration testing for FACET-II pair spectrometer
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A pair spectrometer, designed to capture single-shot gamma spectra over a range extending from 10 MeV through 10 GeV, is being developed at UCLA for installation at SLAC’s FACET-II facility. Gammas are converted to electrons and positions via pair production in a beryllium target and are then subsequently magnetically analyzed. These charged particles are then recorded in an array of quartz Cherenkov cells attached to silicon photomultipliers (SiPMs). As the background environment is challenging, both in terms of ionizing radiation and electromagnetic pulse radiation, extensive beamline testing is warranted. To this end, we present Geant4 Monte Carlo studies, assembly of the SiPMs, and future testing plans.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG67
About: Received: 16 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
Second generation Cherenkov diffraction radiation studies at Diamond Light Source
Diamond Light Source (DLS) is a 3 GeV synchrotron facility in the UK, which has been a part of the Cherenkov diffraction radiation (ChDR) collaboration since 2017 and is now in its second phase of experiments. The current experiment aims to produce and test a one-dimensional beam position monitor (BPM) that utilizes ChDR at visible and near-infrared (NIR) wavelengths. This paper will cover the characterization of the ChDR setup, including: the changes observed to the ChDR signal due to both beam specific and target specific variations.
SUPG056
Real-time measurements of the RF-path of an electro-optical bunch arrival-time monitor with integrated planar pickup structure with low-charge electron beams at ELBE
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Ultra-low-charge operation of free-electron lasers down to 1 pC or even lower, requires adequate diagnostics for both, the users and the operators. For the electro-optical bunch-arrival time monitor (BAM) a fundamental design update is necessary to yield single-digit fs precision with such low charges. In 2023 a vacuum sealed demonstrator for a novel pickup structure with integrated combination network on a printed circuit board (PCB) was built for operation at the free-electron laser ELBE at HZDR. Together with a new low-pi-voltage ultra-wideband traveling wave electro-optical modulator, this concept reaches an estimated theoretical jitter charge product of 9 fs pC. Proof-of-concept measurements with the pickup demonstrator were carried out at ELBE.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG82
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
SUPG057
Simulations of simultaneous measurement of GHz bunches using a fast kicker
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High quality electron bunch trains enable investigations in scientific frontiers with high resolution and efficiency and are earnestly desired by various accelerator facilities, including inverse Compton scattering (ICS), high energy computed tomography, and free electron lasers. An average beam flux can be greatly increased by using the bunch train mode. A bunch train with an average current of 1 A is required in the future steady-state microbunching light source with a bunch spacing of 350 ps (2856 MHz). It is essential to measure each bunch in a bunch train and ensure that each bunch has roughly the same quality. Thus, we proposed utilizing a fast kicker to measure different bunches simultaneously. Different bunches get varying deflection angles by utilizing the kicker's rapidly rising edge, and eventually, different bunches can be measured simultaneously. The measuring methods of real space bunches profile, bunch energy, longitudinal phase space, and its corresponding simulation results are presented.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG89
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
SUPG058
Detailed characterization of coherent synchrotron radiation effects using generative phase space reconstruction
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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.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG94
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
SUPG059
Automation upgrade of the CXLS photoinjector
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The automation upgrade of the photoinjector for the Compact X-Ray Light Source (CXLS) at Arizona State University is described. As the accelerator vault of the CXLS is only 10 meters long, the photoinjector drive laser is located in an enclosure inside the vault. Since ionizing radiation is present in this room during operations, it necessitates remote control of all devices used to optimize the laser spot. This includes multiple shutters, Galil motors, picomotors, a mirror flipper, LEDs, and remote lens controllers. To actuate these devices, a GUI was created with the use of MATLAB AppDesigner which communicates with the hardware through EPICS (Experimental Physics and Industrial Control System). Challenges with this GUI are described, along with the team’s efforts to finalize the control software. After these upgrades, the photoinjector laser characteristics can be adjusted remotely during operation and changes to the drive laser’s position, shape, and intensity can be made without interrupting beam time.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPG14
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
SUPG060
Generation of symmetrical optical caustic beams for precise alignment
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Generating layers of symmetrical optical caustic beams using a specific configuration of cylindrical lenses is an innovative idea with potential application in precision alignment and other fields. The technique allows the generation of layers of non-diffracting beams with opposite accelerating directions. This approach can be extended in two dimensions or to create rotationally symmetric beams. Prior methods have produced similar beams using spatial light modulators, but the presented approach with cylindrical lenses reduces setup complexity and cost, thereby opening the possibility for new applications. In the context of particle accelerators, these include particle acceleration using high-power lasers and alignment of accelerator components. The presented research emphasizes the possibility for this technique to be used as a reference line for precise alignment. It allows the generation of reference lines with a thickness in the order of millimeters for distances of tens to hundreds of meters, which is advantageous for large accelerator facilities. A brief description of the sensors used to detect misalignment is also presented.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPG35
About: Received: 14 May 2024 — Revised: 22 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
SUPG061
CXLS ionizing and laser radiation safety interlock systems
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The Compact X-ray Light Source (CXLS) requires the acceleration of electron bunches to relativistic energies, which collide with focused IR laser pulses to produce X-rays which are then transported to the experiment hutch. A class 4 UV laser is used at the photocathode to liberate the electrons that are generated via the photoelectric effect. During electron acceleration bremsstrahlung radiation (gamma and neutron) is generated through electron interactions with solid matter. In the experiment hutch the X-rays then interact with the sample under test in pump-probe configuration where the pump laser is another class 4 laser with a wide spectral range from deep UV to THz. Interlock systems have been designed and deployed to protect users of the facility from exposure to these ionizing and laser radiation hazards. We present the design architecture of CXLS interlock systems. In this description we make clear what systems are independent, and which are interdependent and what administrative override modes are made available and why. We also provide an overview of our monthly interlock system testing protocols and conclude with comments on overall system performance.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPG41
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
SUPG062
Characterization of meter-scale Bessel beams for plasma formation in a plasma wakefield accelerator
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A large challenge with Plasma Wakefield Acceleration lies in creating a plasma with a profile and length that properly match the electron beam. Using a laser-ionized plasma source provides control in creating an appropriate plasma density ramp. Additionally, using a laser-ionized plasma allows for an accelerator to run at a higher repetition rate. At the Facility for Advanced Accelerator Experimental Tests, at SLAC National Accelerator Laboratory, we ionize hydrogen gas with a 225 mJ, 50 fs, 800 nm laser pulse that passes through an axicon lens, imparting a conical phase on the pulse that produces a focal spot with an intensity distribution described radially by a Bessel function. This paper overviews the diagnostic tests used to characterize and optimize the focal spot along the meter-long focus. In particular, we observe how wavefront aberrations in the laser pulse impact the peak intensity of the focal spot. Furthermore, we discuss the impact of nonlinear effects caused by a 6 mm, CaF2 vacuum window in the laser beam line.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPS82
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
SUPG063
PIP-II laser beam profile monitor laser system
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Fermilab is currently engaged in the development of an 800 MeV superconducting RF linac, aiming to replace its existing 400 MeV normal conducting linac. PIP-II is a warm front-end producing 2 mA of 2.1 MeV H-, followed by a sequence of superconducting RF cryomodules leading to 800 MeV. To mitigate potential damage to the superconducting RF cavities, PIP-II uses laser-based monitors for beam profiling via photoionization. This abstract provides an update on the project’s beam profiling, focusing on advancements made since the initial prototype. The prototype profile monitor featured a high-repetition-rate, low-power fiber laser and fiber optic transport that was tested with a 2.1 MeV H- beam at the PIP-II Injector Test (PIP2IT) accelerator. Since then, the fiber laser and fiber transport have been upgraded to a diode laser based system and free-space optical transport. This highlights a significant evolution in the laser system, enhancing its efficiency and adaptability. This paper will focus on an alternative laser system for the transverse beam measurements. The new system will use a variable pulse-width drive laser system via gain-switching, and the newly implemented free-space propagated optical beam
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPS84
About: Received: 15 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
SUPG064
Improvements of longitudinal stability with LLRF optimization at SIRIUS
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SIRIUS is a 4th generation synchrotron light source built and operated by the Brazilian Synchrotron Light Laboratory (LNLS). Recently, investigations of noise sources and the storage ring RF plant identification enabled a fine-tuning of the Digital Low-Level Radio Frequency (DLLRF) parameters. This paper presents the main improvements implemented, which include the mitigation of 60Hz noise from the LLRF Front End and the optimization of the control system parameters. Optimizations in the machine were based on an adjusted model of the SIRIUS storage ring RF plant. Tests with the model's parameters showed that the system's stability was strongly dependent on phase shifts introduced by nonlinearities from the high power RF sources. The new parameters significantly improved the control performance, increasing the bandwidth of the system and reducing longitudinal oscillations. BPM (Beam Position Monitor) and BbB (Bunch-by-Bunch) systems were employed to quantify longitudinal beam stability improvements.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPG69
About: Received: 14 May 2024 — Revised: 20 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
SUPG065
AGS Booster model calibration and digital-twin development
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An accurate physics simulation model is key to accelerator operation because all beam control and optimization algorithms require good understanding of the accelerator and its elements. For the AGS Booster, discrepancies between the real physical system and online simulation model have been a long-standing issue. Due to the lack of a reliable model, the current practice of beam control relies mainly on empirical tuning by experienced operators, which may be inefficient or sub-optimal. In this work, we investigate two main factors that can cause discrepancies between simulation and reality in the AGS Booster: magnet misalignments and magnet transfer functions. We developed a orbit response measurement script that collects real machine data in the Booster for model calibration. By matching simulated data with real data, we can develop a more accurate simulation model for future polarization optimizations, and build the foundation for a fully functional digital-twin.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPG78
About: Received: 15 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
SUPG066
Autofocusing accelerator beams
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A novel tuning approach, Model Coupled Accelerator Tuning (MCAT), has been applied to the separated function DTL at TRIUMF's Isotope Separator and Accelerator (ISAC). A digital twin of the rare-isotope postaccelerator is used for transverse and longitudinal tune optimizations, which are then loaded directly into the control system. Beam-based testing produced accelerated beam with a 0.26% error in output energy, with a 1.6% energy spread. This method significantly reduces the operational complexity of tuning interventions, rendering them more efficient. An analysis of the high energy beam lines (HEBT) is also presented, including analysis of dispersive couplings in certain sections of the beamline. A mitigation strategy involving buncher cavities is discussed.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPG87
About: Received: 15 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
SUPG067
Dark current simulations in accelerating structures operating with short RF pulses
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The attainable acceleration gradient in normal conducting RF accelerating structure is limited by RF breakdown, a major challenge in high gradient operation. Some of the recent experiments at the Argonne Wakefield Accelerator (AWA) facility suggest the possibility of breakdown mitigation by using short RF pulses (on the order of a few nanoseconds) to drive the accelerating structures. To understand the physics of RF breakdown on a nanosecond time scale, we simulated the dark current in few accelerating structures in both long-pulse and short-pulse regimes comparatively, and studied multiple potential breakdown initiators, including field emission and multipacting. Our simulations suggest the potential of a class of accelerators designed to work in the short-pulse regime.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPR11
About: Received: 15 May 2024 — Revised: 18 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
SUPG068
RF design of a C-band spherical pulse compressor for Super Tau-Charm linac
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Pulse compressors have been widely used to generate very high peak RF power in exchange for the reduction in the RF pulse length for linear accelerators. As compared to a traditional SLAC Energy Doubler(SLED), a spherical pulse compressor is more compact while maintaining a high energy gain. A C-band spherical pulse compressor is studied in this paper, which consists of a dual-mode polarized coupler for producing two orthogonal TE11 modes simultaneously, as well as a resonant cavity working at TE113 mode for storing energy. Through optimizations, an average energy gain of 4.7 with a coupling factor of 6.6 can be achieved for such a spherical pulse compressor. The RF design of this pulse compressor has been finalized, the fabrication and measurement of prototype can be expected in the next step.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPR20
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
SUPG069
New design techniques on matching couplers for travelling wave accelerating structures
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Numerical optimizations on couplers of the traveling wave accelerating structures usually require lots of calculation resources. This paper proposes a new technique for matching couplers to an accelerating structure in a more efficient way. It combines conventional Kroll method with improved Kyhl method, thereby simplifying the tuning and simulation process. We will present the detailed design of a constant-gradient C-band accelerating structure based on this new method.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPR22
About: Received: 14 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
SUPG070
Design of an X-band parallel-coupled travelling-wave accelerating structure for future linacs
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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.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPR19
About: Received: 14 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
SUPG071
Novel materials for beam acceleration
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Bulk niobium is currently the standard material for constructing superconducting radio frequency (SRF) cavities for acceleration in particle accelerators. However, bulk niobium is limited, and new materials and surface treatments may allow greater performance to be reached. We present progress on novel materials and treatments for SRF cavity fabrication.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPS15
About: Received: 20 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
Parameters and process study of copper chamber coating with niobium thin films in DC and HIPIMS modes
This study primarily investigates the parameters and processes involved in depositing Nb thin films on copper cavities under DC and HIPIMS modes. For this purpose, a high-power magnetron sputtering system was designed, conducting a total of 36 experiments. Improvement and optimization of parameters such as duty cycle (under HIPIMS mode), peak current, and bias voltage were undertaken to enhance film quality and performance metrics such as density. Surface morphology and superconducting properties of the films were characterized using SEM, XRD, Tc measurements, and other analytical methods. It was found that the Nb film deposited at a bias voltage of 100 V and a peak current of 150 A exhibited better performance. Lateral analysis of films deposited on different areas of the cavity revealed that in the DC mode, film grain sizes at the cell level were smaller with more defects, whereas in the HIPIMS mode, the niobium film exhibited finer and elongated grains, with grain sizes across various parts of the cavity being closer and defects reduced. This resulted in greater internal uniformity within the entire cavity, contributing to the enhancement of Q and E.
SUPG073
Superconducting thin films on higher order mode antennas to increase the CW performance of SRF cavities at MESA
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The Mainz Energy-Recovering Superconducting Accelerator (MESA), an energy-recovering (ER) LINAC, is currently under construction at the Institute for Nuclear physics at the Johannes Gutenberg-Universität Mainz, Germany. In the ER mode continues wave (CW) beam is accelerated from 5 MeV up to 105 MeV. The energy gain of the beam is provided through 2 enhanced ELBE-type cryomodules containing two 1.3 GHz 9-cell TESLA cavities each. By pushing the limits of the beam current up to 10 mA, a quench can occur at the HOM Antennas. The quench is caused through the increased power deposition induced by the electron beam in ER mode. Calculation shown that an upgrade from 1 mA to 10 mA is increasing the deposited power in the HOMs up to 3080 mW. 30% of this power will be out coupled with the HOM couplers and can be used as a thermal input. Simulations show a power limit of 95 mW which includes the power for 1 mA but is exceeded at 10 mA. A solution to increase the power limit are superconducting thin films which provides higher critical fields, temperature and currents. As candidates are Nb3Sn and NbTiN are chosen. First simulations of the power limit for coated HOM antennas are shown.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPS32
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
SUPG074
Investigation of hot-spots due to local trapped flux in niobium superconducting radiofrequency cavities
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One of the significant sources of residual losses in superconducting radio-frequency cavities is magnetic flux trapped during the cool-down due to the incomplete Messier effect. If the trapped vortices are non-uniformly distributed on the cavity surface, the temperature mapping revealed the “hotspots” at the location of high density of pinned vortices. Here, we performed a rf test on 1.3 GHz single cell cavity with the combination of the temperature mapping system. The temperature mapping reveled the development of the hot spots with the increase in rf field inside the cavity. When magnetic field is trapped locally on the surface of cavity, the hot-spots strength increase rapidly, showing the direct correlation of vortex induced hot spot and corresponding rf loss.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPS34
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
SUPG075
Devices and preparation methods for niobium coupon samples used to investigate high-Q mechanism
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A surface treatment device has been established at the Wuxi Platform, enabling chemical polishing treatment on coupon samples. Currently, several samples treated with buffered chemical polishing (BCP) have been utilized in the investigation of nitrogen doping and medium-temperature baking mechanisms. This paper presents the development process of this device along with the experimental outcomes. In the future, we plan to enhance the device to facilitate electropolishing (EP) treatment on coupon samples.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPS44
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
SUPG076
Buffered chemical polishing process for SHINE 3.9 GHz cavities
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The linear acceleration part of the SHINE project consists of two 3rd harmonic cryogenic modules which are operating at 3.9 GHz. Each of the cryomodules consists of eight 3.9 GHz 9-cell superconducting cavities. The SHINE specifications of the 3.9 GHz cavities are Qo >2.0e+9@13.1 MV/m and maximum accelerating gradient >15 MV/m. The 3.9 GHz cavities were treated with buffered chemical polishing (BCP) baseline combined with 2-step low-temperature baking surface treatment process to meet the specifications. In order to achieve the required performance, the BCP process had been optimized at the SHINE Wuxi surface treatment platform, especially the acid ratio. Vertical tests of all 3.9 GHz bare cavities treated with the optimized BCP process showed Qo up to 3.0e+9@13.1 MV/m and maximum accelerating gradient over 20 MV/m. The optimized BCP process applied to the 3.9 GHz cavities and related vertical test results were presented in this paper.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPS46
About: Received: 16 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
SUPG077
Decoupling of nitrogen and oxygen impurities in nitrogen doped SRF cavities
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The performance of superconducting radiofrequency (SRF) cavities is critical to enabling the next generation of efficient, high-energy particle accelerators. Recent developments have focused on altering the surface impurity profile through in-situ baking, furnace baking, and doping to introduce and diffuse beneficial impurities such as nitrogen, oxygen, and carbon. However, the precise role and properties of each impurity are not well understood. In this work, we attempt to disentangle the role of oxygen and nitrogen impurities through time-of-flight secondary ion mass spectrometry of niobium samples baked at temperatures varying from 75-800°C with and without nitrogen injection. From these results, we developed treatments recipe that decouple the effects of oxygen and nitrogen in doping treatments. Understanding how these impurities and their underlying mechanisms drive further optimization in the tailoring of impurity profiles for high performing SRF cavities.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPS58
About: Received: 21 May 2024 — Revised: 22 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
SUPG078
Microscopic understanding of the effects of impurities in low RRR SRF cavities
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The SRF community has shown that introducing certain impurities into high-purity niobium can improve quality factors and accelerating gradients. We question why some impurities improve RF performance while others hinder it. The purpose of this study is to characterize the impurities of niobium coupons with a low residual resistance ratio (RRR) and correlate these impurities with the RF performance of low RRR cavities so that the mechanism of impurity-based improvements can be better understood and improved upon. The combination of RF testing, temperature mapping, frequency vs temperature analysis, and materials studies reveals a microscopic picture of why low RRR cavities experience low BCS resistance behavior more prominently than their high RRR counterparts. We evaluate how differences in the mean free path, grain structure, and impurity profile affect RF performance. The results of this study have the potential to unlock a new understanding on SRF materials and enable the next generation of high Q/high gradient surface treatments.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPS59
About: Received: 22 May 2024 — Revised: 22 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
SUPG079
Waveguide system for an SRF cryomodule in KEK
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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.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPR37
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
SUPG081
Findings of simulation studies for the fast corrector magnets of PETRA IV
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Fourth-generation synchrotron radiation sources, which are currently being planned in several accelerator laboratories, require fast orbit feedback systems to correct distortions in the particle orbit in order to meet stringent stability requirements. Such feedback systems feature corrector magnets powered at frequencies up to the kilohertz range, giving rise to strong eddy currents. To understand the eddy current effects and the characteristics of these fast corrector magnets, elaborate finite element simulations must be conducted. This paper gives an overview of the most important findings of our simulation studies for the fast corrector magnets of the future synchrotron radiation source PETRA IV at DESY, Hamburg, Germany. Using a homogenization technique for the laminated yokes, we simulate the magnets over a wide frequency range.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPR53
About: Received: 05 May 2024 — Revised: 17 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
SUPG082
Research on design of a novel permanent quadrupole magnet
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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.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPR55
About: Received: 13 May 2024 — Revised: 19 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
Mapping of an SRF electron gun focusing solenoid assembly
SLAC’s LCLS-II-HE upgrade will expand the energy regime of their XFEL at high repetition rates. Due to the low emittance requirement, a superconducting QWR based electron gun was proposed by SLAC and is being developed by FRIB in collaboration with ANL and HZDR. The emittance compensation solenoid consists of two main coils, along with horizontal and vertical dipoles as well as normal and skew quadrupole correctors. To validate the performance and characterize the field profile of the magnet, we developed a mapper system. We utilized a SENIS 3D Hall probe on a cantilevered rail driven by an Arduino controlled stepper motor. With high repeatability, we were able to measure peak field strengths and fall off. Further data analysis allowed us to determine their relative locations, in addition to confirming alignment and integrated field strengths. In accordance with design specifications, we measured the peak solenoid fields to be about 172mT and their centers to be less than 0.1mm apart transversely. The mapping design, assembly, process, analysis, and lessons learned are discussed herein.
SUPG084
Status of coil-dominated discrete-cosine-theta quadrupole prototype for high rigidity isotope beams
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Iron-dominated superconducting magnets are one of the most popular and used design choices for superconducting magnetic quadrupoles for accelerator systems. While the iron yoke and pole tips are economic and effective in shaping the field, the large amount of iron also leads to certain drawbacks, namely, unwanted harmonics from the sextupole correctors nested inside of quadrupole iron pole tips. Additional problems include the nonlinear field profile present in the high-field regime caused by the presence of steel, the cryogenic design challenges of the iron yoke being part of the cold mass, and the mechanical challenges of mounting the sextupole and octupole, which will generate significant forces for apertures of the size being proposed. The Facility for Rare Isotope Beams is developing a coil dominated quadrupole as a future upgrade, and the presented work discusses the advantages of using an iron-free quadrupole, along with the methods and choices of the design and the current status of prototype fabrication. The methods and work presented will include the model results and the aspects of the model that have been verified up to the current status of prototype fabrication.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPS67
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
SUPG085
The FORTRESS beamline at Tsinghua university
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High-brightness photoinjectors generate low emittance, ultrashort electron beams that are capable of tracking dynamical states of matter with atomic-scale spatio-temporal resolutions via ultrafast electron scattering, as well as providing precisely-shaped electron beams for advanced acceleration research and large-scale facilities such as free-electron laser and inverse Compton scattering. In this paper, we report on the status of the newly constructed FORTRESS (Facility Of Relativistic Time-Resolved Electron Source and Scattering) beamline at Tsinghua University, which will be dedicated for studies of advanced electron sources and photocathodes, new electron beam manipulation and characterization methods, and ultrafast electron scattering applications. The layout, beam dynamics simulation, initial beam measurement results, as well as main hardware components will be discussed in detail.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC16
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
Enhanced harmonic stability in magnet resonant power supplies via multi-harmonic closed-loop control and current feedforward
As the China Spallation Neutron Source (CSNS) Phase II project upgrades beam power to 500 kW, maintaining horizontal beam orbit stability necessitates more precise output current from the main magnet power supplies. The existing control strategy, suited for 100 kW extraction power, falls short of the higher precision requirements for the output current, characterized by a quasi-sinusoidal waveform with 25 Hz and its higher-order harmonics. Moreover, this strategy is highly sensitive to environmental temperature, causing significant fluctuations in the amplitude and phase of the high-order harmonics, thereby adversely affecting the power supplies' performance. This paper proposes a new control scheme that merges high-order harmonic current compensation with double PI closed-loop control, enabling up to sixth harmonic control in the main magnet power supplies. Leveraging the existing Digital Power Supply Control Module (DPSCM) controller in the power supply system, this approach achieves precise and efficient control of the 50 Hz harmonic current output which was previously the source of the largest ripple error. The study confirms that the new control scheme effectively mitigates temperature drift issues and reduces the output ripple of the entire 50 Hz reference current waveform. As a result, the performance of the main magnet resonant power supplies in Rapid Cycle Synchrotron is significantly enhanced, leading to a marked reduction in the variation of beam orbit deviation.
SUPG087
Analysis of laser engineered surface structures’ roughness and surface impedance
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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.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPR58
About: Received: 14 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
SUPG088
Simulation study of nanosecond pulse power based on gyromagnetic nonlinear transmission line
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On-axis injection mode is planned to use in the Southern Advanced Photon Source (SAPS), which requires high quality to injection pulsed power supply. Gyromagnetic nonlinear transmission line (GNLTL) is introduced as a pulse compressor to meet the needs for pulse width. In this paper, 3-D finite element model is established based on Landau-Lifshitz-Gilbert equation and Maxwell’s equations. The influence of geometrical sizes and bias magnetic field to output pulse is analyzed for better design of NLTL. A prototype was built with nanosecond pulse width and sub-nanosecond rise time to verify the simulation.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPS29
About: Received: 15 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
SUPG090
Exploring high gradient limit with cryogenic experiments at FREIA laboratory
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Field emission (FE) and vacuum arcs limit the maximum achievable accelerating field of both normal and superconducting cavities. The performance of accelerating cavities can be improved after a long conditioning process. Understanding this process and the formation of vacuum arcs is important for all technologies where vacuum arcs cause device failure. The understanding could be more complete with novel diagnostic tools and tests in variable environments. The cryogenic HV system in FREIA laboratory is used to study different aspects of conditioning using DC pulses at a wide range of temperatures, down to 4K. We are currently measuring FE currents during conditioning for Cu, Nb and Ti electrodes in function of temperature and breakdown rate. We are also developing a new characterization method, evaluating the surface resistivity of the electrodes during conditioning. Changes in the surface resistivity could indicate the formation of dislocations below the surface, which has been speculated to be a very important process behind conditioning. We will present the results of conditioning with the FE measurements and the surface resistivity measurements.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPR86
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
SUPG091
Magnetic measurements for Halbach-type permanent quadrupoles using a single-stretched wire system
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In the framework of the acceleration techniques, the Plasma Wake Field Acceleration (PWFA) is one of the most promising in terms of high machine compactness. For this purpose, a crucial role is played by the particle beam focusing upward and downward the plasma-beam interaction, performed by high gradient Permanent Magnet Quadrupoles (PMQs). In the framework of the INFN-LNF SPARC_LAB (Sources for Plasma Accelerators and Radiation Compton with Laser And Beam) six Halbach-type PMQs have been tested before installing them into the machine. This paper presents the outcomes of magnetic measurements conducted using a Single-Stretched Wire (SSW) system. The results include comprehensive details on integrated gradients, magnetic multipole components, and roll angles of the magnets. By considering the operational parameters of the machine, the results show that the tested magnets can be feasibly installed only within limited triplets configurations.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPS54
About: Received: 14 May 2024 — Revised: 20 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
Topology optimization of a dipole magnet using normalized gaussian network
The precision of the proton therapy beam depends on maintaining high field quality in the magnet’s good field region. Iron yoke is employed in magnets to increase the magnetic field and reduce the fringe field. However, when providing a high magnetic field for transporting relatively high-energy particles, the saturation effect of the yoke can distort the field quality. To mitigate this effect, tuning holes and pole shape optimization are adopted in the iron yoke to adjust the magnetic flux, which helps in maintaining a higher field quality for particles with different energies. Optimizations are often limited by human expertise. In this paper, we use a topology optimization method that employs a non-dominated sorting genetic algorithm for the prototype design of an iron yoke in a dipole magnet. To achieve a smooth distribution of material, we represent the shape of the iron yoke using a normalized Gaussian network. This method effectively mitigates the field error at different energy levels. Shape optimization is performed to compare it with topology optimization. It is suitable for the application of topology optimization in the beam line system for the proton therapy system.
SUPG093
Experimental design for validating the feasibility of in-situ plasma cleaning of normal conducting copper cavities
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To reduce the dark current and secondary electron multiplication in conventional conducting accelerator cavities, and to improve the quantum efficiency of copper photocathodes, thereby achieving higher beam quality and enhancing the acceleration gradient and operational stability of accelerators, Tsinghua University designed a 13.56 MHz internal coil-type capacitive discharge plasma experimental platform to validate the feasibility of in-situ plasma cleaning of conventional superconducting copper cavities. This paper mainly introduces the architecture of this experimental platform, including the structure of the experimental cavity and its accompanying gas system, microwave system, and monitoring system. This experiment also validates the oxidation and reduction capabilities of the active components in the plasma, particularly comparing the oxidation ability of excited oxygen atoms and oxygen ions and the reduction ability of excited hydrogen atoms and hydrogen ions. This experimental platform can be used for cleaning and reduction of small and simple copper structures and verifies the feasibility of In-situ plasma cleaning of conventional conducting copper cavities.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPS66
About: Received: 14 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
SUPG094
Mechanical design, structural requirements and optimization of the FCC e+e- interaction region components
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This paper describes the mechanical design of the Future Circular Collider e+e- interaction region. The Future Circular Collider, as a forefront particle accelerator project, demands meticulous attention to the mechanical integrity and performance of its components, to the integration of the different systems and to the respect of the spatial constraint. The vacuum chamber design, the support tube and the bellows design are reported, highlighting the solutions adopted. The structural optimization method of the support structure is also presented, as well as the results obtained.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPS69
About: Received: 14 May 2024 — Revised: 19 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
SUPG095
A large momentum acceptance gantry for light-weight proton therapy facility: its beam lattice, magnets design and clinical advantages
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As one of the state-of-the-art radiotherapy approaches, proton therapy possesses conformal dose profiles yet expensive cost. Designing a facility with a small footprint and a high treatment efficiency is the main goal for researchers to fulfill the potential of proton therapy and make it more affordable both for vendors and patients. In this contribution, the design of a light-weight proton therapy gantry based on the alternating-gradient canted-cosine-theta (AG-CCT) super-conducting (SC) magnet is presented. The AG-CCT magnets adopt large bores and combined function design. With fine field harmonic control and fringe field shape optimization of the magnets, the multi-particle tracking results prove that the gantry achieves a momentum acceptance of ±8%. So that the full energy range from 70 to 230 MeV can be covered with merely 3 field switch points. Combined with a fast degrader component, whose switch time is below 50 ms, the energy modulation speed can be greatly fastened. To fully utilize the advantages of the large momentum acceptance gantry, the energy spread of the proton beam is expanded and a reduced treatment plan is proposed. Compared with the standard treatment plan, the energy layers number of a prostate case is reduced by 61.3% with comparable plan quality. In summary, the proposed gantry has significant superiority both in manufacture and clinical aspects.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPR51
About: Received: 14 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
SUPG096
Fabrication and tuning of a 325 MHz ion-injector prototype for particle therapy facility
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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.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPR58
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
SUPG097
Focusing of high-energy electron beam using silicon crystals for application in radiotherapy
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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.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPR61
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
SUPG098
Current status of MINIBEE: minibeam beamline for preclinical experiments on spatial fractionation in the FLASH regime
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In vivo studies support that the combination of protons and spatial fractionation, the so-called proton minibeam radiotherapy (pMBT), enhances the protection of normal tissue for a given tumor dose. A preclinical pMBT facility for small animal irradiation at the 68 MeV cyclotron of Helmholtz-Zentrum Berlin (HZB) will improve the understanding of this method. A two-step energy-degrading system will first define the maximum energy of the beam and further degrading will occur before the target forming a spread-out Bragg peak (SOBP), if necessary. Beam size and divergence will be adjusted by slit systems before a 90-degree magnet bending the beam into the experimental room. At the current stage, a magnetic quadrupole triplet placed close to the target demagnifies the beam by a factor of ~5. The goal is to generate a magnetically focused minibeam of 50 micrometer sigma. Scanning magnets will enable a raster-scan application in the tumor. Conventional dose rate delivery will be allowed while FLASH applications can be achieved with the possible use of a ridge filter. The results of beamline simulations by TRACE-3D and BDSIM will be presented.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPR62
About: Received: 14 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
Thermal diffusivity and acoustic properties of Nb thin films studied by time-domain thermoreflectance
The thermal diffusion and acoustic properties of Nb impacts the thermal management of devices incorporating Nb thin films such as superconducting radiofrequency (SRF) cavities and superconducting high-speed electronic devices. The diffusion and acoustic properties of 200-800 nm thick Nb films deposited on Cu substrates were investigated using time-domain thermoreflectance (TDTR). The films were examined by X-ray diffraction, scanning electron microscopy, and atomic force microscopy. The grain size and thermal diffusivity increase with film thickness. The thermal diffusivity increased from 0.100± 0.002 cm2s-1 to 0.237± 0.002 cm2s-1 with the increase in film thickness from 200 nm (grain size 20±6 nm) to 800 nm (grain size 65±16 nm). Damped periodic photoacoustic signals are detected due to laser heating generated stress in the Nb film, which results in an acoustic pulse bouncing from the Nb/Cu and the Nb/vacuum interfaces. The period of the acoustic oscillation gives a longitudinal sound velocity of 3637.3 ms-1 inside the Nb films, which is in good agreement with the values reported in the literature.
Effects of implantation temperature and annealing on structural evolution and migration of ruthenium in glassy carbon
The use of glassy carbon (GC) as a future nuclear waste storage material depends on its capability to retain all radioactive fission products found in spent nuclear fuels. Ruthenium (Ru) is one of the most important fission products in nuclear reactors. This work investigates the effects of implantation temperature and annealing on the structural evolution and migration of Ru implanted in GC. To achieve these objectives, 150 keV Ru+ was implanted into GC samples separately at room temperature (RT) and 200°C to a fluence of 1×10^16 cm^−2. Some of the as-implanted samples were annealed at two temperature regimes (from 500 to 1000°C and from 1000 to 1300°C–in steps of 100°C) for 5 h and characterized by Raman spectroscopy, X-ray diffraction (XRD), atomic force microscopy (AFM), and Rutherford backscattering spectrometry (RBS). Both Raman spectroscopy and XRD showed that implantation caused defects in the GC structures, with more defects in the RT as-implanted sample. Annealing caused the healing of both sample types but retained some radiation damage. No migration of Ru atoms was observed after annealing the as-implanted samples up to 800°C. However, a different migration behavior was seen after annealing the RT and 200°C samples from 900 to 1300°C, attributed to the aggregation, trapping and de-trapping of Ru atoms in different amounts of defect induced by implantation.
SUPG101
Progress on pulsed electron beams for radiation effects characterization of electronics
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Ultrafast high-energy pulsed electron beams can provide deep penetration and variable linear energy transfers by controlling the characteristics of the electron bunch, both of which currently oversubscribed heavy ion facilities cannot provide. Early experiments at the UCLA PEGASUS beamline (~3 MeV) with ~1 ps electron bunches and a 50 μm spot size yielded charge collection transients that were not correlated well with standard heavy-ion data. Sub-micron focusing of the beam would allow for the electron bunch to mimic ion tracks by saturating the charge collection in a small cross-sectional area while simultaneously providing high spatial resolution to allow for the targeted testing of microelectronic components. Using a 10 μm collimator and strong lens, current experiments are planned at UCLA to characterize standard photodiodes with smaller spot sizes to achieve stronger correlations with the heavy-ion data.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPR77
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
The design of a rocket based RF electron accelerator for space applications
Beam Plasma Interactions Experiment (Beam-PIE) is a NASA sounding rocket experiment that successfully ran in November 2023. Beam-PIE used space as a laboratory to explore wave generation from a modulated electron beam in the ionosphere. Beam-PIE electron accelerator used a 10keV electron gun and a 5-GHz RF cavity, enabling the acceleration of the electron beam to a total energy of ~25–60 keV. The experiment was pulsed at VLF frequencies ranging from 5 to 500 kHz. The third parameter was duty cycle which ranged from 2.5% to 10%. In total, 32 different combinations of beam parameters were used and repeated every 32 seconds through the flight at various altitudes and background plasma conditions. Each of these different beam parameters ran for a ½-second beam pulse, separated by ½-second intervals when the beam was off. Beam-PIE was successful at generating plasma waves. We present an outline of the accelerator design, theoretical predictions, and experimental results of generated plasma waves. Results will be used to quantitatively test our understanding of beam-plasma-wave interactions in the space environment with applications to space communication and radiation belt remediation.
SUPG103
The gamma activation measurements at Shanghai Laser Electron Gamma Source
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SLEGS is a Laser Compton Scattering gamma source. The gamma energy is 0.66 to 21.7 MeV, and the gamma flux is approximately 4.8e+5 to 1.5e+7 phs/s. Gamma activation method is used in beam flux monitor, medical isotpoe production and nuclear astrophysics in SLEGS*. Gamma beam flux under different collimated apertures has been checked by gamma activation method by using various half-life nuclide targets with an online activation and offline measurement platform. It is consistent with the flux measured with direct method by the LaBr3 detector. The activation method will be uniquely advantageous for monitoring gamma beam with short-life nuclide in a short time.A series of potential medical isotopes giant resonance production cross sections are measured by gamma activation method, which will provide key data for medical isotopes production by photonuclear reactions. The p-nuclei’s photonuclear cross sections**, for example Ru, are measured by photoneutron and gamma activation, which can provide favorable data on the much larger abundance of 98Ru, 96Ru. The activation experiment of SLEGS provides a reliable option for different experimental research objectives in photonuclear physics.
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPR86
About: Received: 17 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024