bluuebunny/crossref_metadata_2025_split huggingface dataset:
Beam orbit shift due to BPM thermal deformation using machine learning
Authors: Chen Kemin , Wang Faya , Wang Guanliang , Wang Zhe , Hosaka Masahito , Guo Lei , Xu Wei 
Published: January 2023

Abstract
Stabilizing beam orbit is critical for advanced synchrotron radiation light sources. The beam orbit can be affected by many sources. To maintain a good orbit stability, global orbit feedback systems (OFB) has been widely used. However, the BPM thermal deformation would lead to BPM misreading, which can not be handled by OFB. Usually, extra diagnostics, such as position transducers, is needed to measure the deformation dependency of BPM readings. Here, an alternative approach by using the machine operation historic data, including BPM temperature, insertion device (ID) gaps and corrector currents, is presented. It is demonstrated at Hefei Light Source (HLS). The average orbit shift due to BPM thermal deformation is about 34.5 μm/°C (horizontal) and 20.0 μm/°C (vertical).
Dependence of CsK2Sb photocathode performance on the quality of graphene substrate film
Authors: Guo L , Goto K , Yamaguchi H , Yamamoto M , Takashima Y 
Published: January 2023

Abstract
A high-performance photocathode is required to advanced accelerators and electron microscopes. In particular, the CsK2Sb photocathode is of interest because it has features such as low emittance, excitability with visible light, and high quantum efficiency (QE). Generally, the CsK2Sb photocathode is produced by depositing a cathode element on a substrate, so that the cathode performance strongly depends on the surface condition of the substrate. We have found graphene as reusable substrate, which has the property of being chemically inactive. In this study, graphene film quality dependence of CsK2Sb photocathode performance was evaluated. Specifically, CsK2Sb photocathode was deposited using different quality graphene film substrates and their QE values and uniformity were compared. The quality of graphene films was analyzed using X-ray Photoelectron Spectroscopy (XPS) and X-ray Absorption Spectroscopy (XAS). We found that the graphene film can be cleaned by heating at 500 deg. The QE of the cathode on a good quality graphene film was higher and more uniform than that on a poor quality graphene film.
Start-to-end simulations for bunch compressor and THz SASE FEL at PITZ
Authors: Lueangaramwong A , Li X , Boonpornprasert P , Krasilnikov M , Stephan F 
Published: January 2023

Abstract
The magnetic bunch compressor was designed as part of a THz accelerator source being developed at the Photo Injector Test facility at DESY in Zeuthen (PITZ) as a prototype for pump-probe experiments at the European XFEL. As an electron bunch is compressed to achieve higher bunch currents for the THz source, the beam dynamics in the bunch compressor was studied by numerical simulations. A start-to-end simulation optimizer including coherent synchrotron radiation (CSR) effects has been developed by combining the use of ASTRA, OCELOT, and GENESIS to support the design of the THz source prototype. In this paper, we present simulation results to explore the possibility of improving the performance of the THz FEL at PITZ by using the developed bunch compressor.
Tungsten Electron Emitter (TE2) with direct heated cathode by plasma stream
Authors: Thoma K I , Dönges T , Droba M , Meusel O , Podlech H , Schulte-Urlichs K 
Published: January 2023

Abstract
At Goethe-University, a novel concept of heating metallic cathodes is currently under investigation. In the scope of the ARIES collaboration WP16, an RF-modulated electron gun was developed and manufactured for application in electron lenses for space charge compensation. The goal of this project is to increase the intensity of primary beams, especially in low energy booster synchrotrons like the SIS18 and SIS100 at GSI/FAIR or the SPS at CERN. The gun was designed to produce electron currents of 10 A at extraction voltages of 30 kV. The tungsten electron emitter (TE2) and the grid electrode were designed and manufactured to be integrated in the extractor of the original volume type ion source. Significant effort was put into a robust and flexible design with highly reliable key components. The cathode is heated by a plasma stream generated in the plasma chamber of the source. Different heating options of the cathode are currently being studied. This contribution presents the working principles of the electron gun and first measurements results of cathode heating.
Performance of automated synchrotron lattice optimisation using genetic algorithm
Authors: Zhang X , Sheehy S L 
Published: January 2023

Abstract
Rapid advances in superconducting magnets and related accelerator technology opens many unexplored possibilities for future synchrotron designs. We present an efficient method to probe the feasible parameter space of synchrotron lattice configurations. Using this method, we can converge on a suite of optimal solutions with multiple optimisation objectives. It is a general method that can be adapted to other lattice design problems with different constraints or optimisation objectives. In this method, we tackle the lattice design problem using a multi-objective genetic algorithm. The problem is encoded by representing the components of each lattice as columns of a matrix. This new method is an improvement over the neural network based approach in terms of computational resources. We evaluate the performance and limitations of this new method with benchmark results.
High current heavy ion beam investigations at GSI-UNILAC
Authors: Vormann H , Barth W , Miski-Oglu M , Scheeler U , Vossberg M , Yaramyshev S 
Published: January 2023

Abstract
The GSI Universal Linear Accelerator UNILAC and the synchrotron SIS18 will serve as injector for the upcoming FAIR-facility. The UNILAC-High Current Injector will be improved and modernized until FAIR is commissioned and the Alvarez post stripper accelerator is replaced. The reference heavy ion for future FAIR-operation is uranium, with highest intensity requirements. To re-establish uranium beam operation and to improve high current beam operation, different subjects have been explored in dedicated machine investigation campaigns. After a beam line modification in 2017 the RFQ-performance had deteriorated significantly; new rods have been installed and the RF-working point has been redefined. Also the Superlens-performance had become unsatisfactory; improved with a modified RF-coupler. With a pulsed hydrogen gas stripper target the uranium beam stripping efficiency could be increased by 65%. Various work has already been carried out to establish this stripper device in routine operation. With medium heavy ion beams a very high beam brilliance at the end of transfer line to SIS18 was achieved. Results of the measurement campaigns and the UNILAC upgrade activities will be presented.
Design and beam dynamics study of disk-loaded structure for muon LINAC
Authors: Sumi K , Iijima T , Inami K , Sue Y , Yotsuzuka M , Ego H , Otani M , Saito N , Mibe T , Yoshida M , Kondo Y , Moriya K , Takeuchi Y , Nakazawa Y , Yasuda H 
Published: January 2023

Abstract
The disk-loaded structures (DLS) in the muon LINAC are under development for the J-PARC muon g–2/EDM experiment. Four DLSs with an accelerating gradient of 20 MV/m take charge of muon acceleration from 40 MeV to 212 MeV, which corresponds to 70% to 94% of the speed of light. The quasi-constant gradient type TM01-2π/3 mode DLSs with gradually varying disk spacing was designed and it was confirmed that the cumulative phase slip due to the mismatch between muon and phase velocity can be suppressed to less than 2 degrees at the frequency of 2592 MHz. In addition, the optimum synchronous phase and the lattice were investigated to satisfy the requirements of the total emittance less than 1.5π mm mrad and the momentum spread less than 0.1% in RMS.
The Zgoubidoo python framework for ray-tracing simulations with Zgoubi: applications to fixed-field accelerators
Authors: Vanwelde M , Hernalsteens C , Tesse R , Gnacadja E , Ramoisiaux E , Pauly N 
Published: January 2023

Abstract
The study of beam dynamics in accelerators featuring main magnets with complex geometries such as Fixed Field Accelerators (FFAs) requires simulation codes allowing step-by-step particle tracking in complex magnetic fields, such as the Zgoubi ray-tracing code. To facilitate the use of Zgoubi and to allow readily processing the resulting tracking data, we developed a modern Python 3 interface, Zgoubidoo, using Zgoubi in the backend. In this work, the key features of Zgoubidoo are illustrated by detailing the main steps to obtain a non-scaling FFA accelerator from a scaling design. The results obtained are in excellent agreement with prior results, including the tune computation and orbit shifts. These results are enhanced by Zgoubidoo beam dynamics analysis and visualization tools, including the placement of lattice elements in a global coordinate system and the computation of linear step-by-step optics. The validation of Zgoubidoo on conventional scaling and non-scaling FFA designs paves the way for future uses in innovative FFA design studies.
Recent results of beam loss mitigation and extremely low beam loss operation of J-PARC RCS
Authors: Saha P K , Okabe K , Nakanoya T , Shobuda Y , Harada H , Tamura F , Okita H , Yoshimoto M , Hotchi H 
Published: January 2023

Abstract
In the 3-GeV RCS (Rapid Cycling Synchrotron) at J-PARC (Japan Proton Accelerator Research Complex), multi-turn H− charge-exchange injection is performed by using a thin stripped foil. The residual radiation at the injection area caused by the uncontrolled beam loss occurred by foil scattering of the circulating beam is a serious issue for regular maintenance works. In addition, the beam loss at the collimator section and its downstream caused for a large emittance beam also should be reduced, especially at high intensity operation. For that purpose we have minimized injection beam size and implemented a smaller size stripper foil. The circulating beam hitting rate is reduced by using a smaller foil, while an optimized vertical angle of the smaller injection beam for vertical transverse painting also gave a reduction of the circulating beam emittances and resulted a further significant beam loss mitigation at the collimator section and its downstream. As a result, the residual radiation after user operation at 700 kW beam power was also measured to be significantly reduced.
WITHDRAWN: Investigation of spin-decoherence in the NICA storage ring for the future EDM-measurement experiment
Authors: Aksentev A E , Melnikov A A , Senichev Y V , Ladygin V P , Syresin E M 
Published: January 2023

Abstract
This article has been withdrawn by IOP Publishing following the request by the authors to augment their affiliation by an institution. Upon reviewing the matter, IOP Publishing found that the institution (Moscow Institute of Physics and Technology) is subject to sanctions by the UK government.

To ensure compliance with sanctions regulations, this article has been withdrawn from IOPscience.
Horizontal beam response at extraction conditions at the Heidelberg Ion-beam Therapy Centre
Authors: Cortés García E C , Feldmeier E , Haberer Th 
Published: January 2023

Abstract
The Heidelberg Ion-Beam Therapy Centre’s synchrotron makes use of the sextupole driven RF-KO method near the third-order resonance in order to slowly extract the beam that is delivered to the patients. The horizontal beam response of a coasting beam was studied experimentally and with simulations at extraction conditions in order to deduce regions of interest for an optimal excitation signal spectrum. Two narrow frequency regions were found where the beam reacts coherently. With these information an RF signal was proposed for the resonant slow extraction.
Parallelization of Radia magnetostatics code
Authors: Banerjee A , Chubar O , Le Bec G , Chavanne J , Nash B , Hall C , Edelen J 
Published: January 2023

Abstract
Radia 3D magnetostatics code has been used for the design of insertion devices for light sources over more than two decades. The code uses the magnetization integral approach that is efficient for solving permanent magnet and hybrid magnet structures. The initial version of the Radia code was sequential, its core written in C++ and interface in the Mathematica language. This paper describes a new Python interfaced parallel version of Radia and its applications. The parallelization of the code was implemented on C++ level, where the semi-analytical calculations of interaction matrix elements and resultant magnetic fields were parallelized using the Message Passing Interface. The parallel performance results are encouraging, particularly for magnetic field calculation post relaxation where a ∼600 speedup with respect to sequential execution was obtained. The new parallel Radia version facilitates designs of insertion devices and lattice magnets for novel particle accelerators.
Modeling a Nb3Sn cryounit in GPT at UITF
Authors: Pokharel S , Hofler A S , Krafft G A 
Published: January 2023

Abstract
Nb3Sn is a prospective material for future superconducting radio frequency (SRF) accelerator cavities. Compared to conventional niobium, the material can achieve higher quality factors, higher temperature operation, and potentially higher accelerating gradients (Eacc ≈ 96 MV/m). In this work, we performed modeling of the Upgraded Injector Test Facility (UITF) at Jefferson Lab utilizing newly constructed Nb3Sn cavities. We studied the effects of the buncher cavity and varied the gun voltage from 200-500 keV. We have calibrated and optimized the SRF cavity gradients and phases for the Nb3Sn five-cell cavities’ energy gains with the framework of the General Particle Tracer (GPT). Our calculations show the beam goes cleanly through the unit. There is full energy gain out of the second SRF cavity but not from the first SRF cavity due to non-relativistic phase shifts.
Review of alignment and stability tolerances for advanced light sources
Authors: Khan A , Sharma S , Smaluk V 
Published: January 2023

Abstract
Alignment and mechanical-stability specifications are essential to the performance of low-emittance storage rings. Beam dynamics simulations are usually performed to establish these specifications. However, the simulation procedures and the input parameters related to magnet positions are not well established which leads to differences in the final specifications. In this paper we discuss important parameters of the mechanical/structural systems of the storage ring that impact on the alignment and stability specification. We reviewed the alignment and stability specifications used at modern light sources across the world that will help to propose an efficient model for a low-emittance upgrade of NSLS-II.
Space charge analysis for low energy photoinjector
Authors: Carillo M , Behtouei M , Bosco F , Faillace L , Ficcadenti L , Fukasaway A , Giuliano L , Mostacci A , Migliorati M , Spataro B , Rosenzweig J , Palumbo L 
Published: January 2023

Abstract
Beam dynamics studies are performed in the context of a C-Band hybrid photo-injector project developed by a collaboration between UCLA/Sapienza/INFN-LNF/RadiaBeam [1, 2]. These studies aim to explain beam behaviour through the beam-slice evolution, using analytical and numerical approaches. An understanding of the emittance oscillations is obtained starting from the slice analysis, which allows correlation of the position of the emittance minima with the slope of the slices in the transverse phase space (TPS). At the end, a significant reduction in the normalized emittance is obtained by varying the transverse shape of the beam while assuming a longitudinal Gaussian distribution. Indeed, the emittance growth due to nonlinear space-charge fields has been found to occur immediately after moment of the beam emission from the cathode, giving insight into the optimum laser profile needed for minimizing the emittance.
Modeling and mitigation of long-range wakefields for advanced linear colliders
Authors: Bosco F , Camacho O , Carillo M , Chiadroni E , Faillace L , Fukasawa A , Giribono A , Giuliano L , Majernik N , Mostacci A , Palumbo L , Rosenzweig J , Spataro B , Vaccarezza C , Migliorati M 
Published: January 2023

Abstract
The luminosity requirements of TeV-class linear colliders demand use of intense charged beams at high repetition rates. Such features imply multi-bunch operation with long current trains accelerated over the km length scale. Consequently, particle beams are exposed to the mutual parasitic interaction due to the long-range wakefields excited by the leading bunches in the accelerating structures. Such perturbations to the motion induce transverse oscillations of the bunches, potentially leading to instabilities such as transverse beam break-up. Here we present a dedicated tracking code that studies the effects of long-range transverse wakefield interaction among different bunches in linear accelerators. Being described by means of an efficient matrix formalism, such effects can be included while preserving short computational times. As a reference case, we use our code to investigate the performance of a state-of-the-art linear collider currently under design and, in addition, we discuss possible mitigation techniques based on frequency detuning and damping.
Lattice design of the UVSOR-IV storage ring
Authors: Salehi E , Taira Y , Fujimoto M , Guo L , Katoh M. 
Published: January 2023

Abstract
We are designing a storage ring lattice for the future plan of UVSOR. As a candidate, we have designed a storage ring of 1 GeV electron energy, which is higher than the present value, 750 MeV. The magnetic lattice is based on a compact double bend achromat cell, which consists of two bending magnets and four focusing magnets, all of which are of combined function. The circumference is 82.5 m. The emittance is 4 nm in the achromatic condition, which becomes lower in the non-achromatic condition. The lattice has moderately large dynamic aperture with four sextupole families. The lattice of 6-fold symmetry has six straight sections of 4 m long and six of 1.5 m long. Undulators can radiate nearly diffraction-limited light in VUV. If we install high field multipole wigglers at the short straight sections, they can provide high flux tender X-rays. We are expecting usage of a laser-based accelerator as the injector, which might be developed in the next decade. As an alternative plan, we have designed a traditional injector, which consists of a linear accelerator and a booster synchrotron that can be constructed inside of the storage ring.
A method for obtaining 3D charge density distribution of a self-modulated proton bunch
Authors: Nechaeva T , Verra L , Porta G Zevi Della , Muggli P 
Published: January 2023

Abstract
The Advanced Wakefield Experiment (AWAKE) at CERN is the first plasma wakefield accelerator experiment to use a proton bunch as driver. The long bunch undergoes seeded self-modulation (SSM) in a 10 m-long plasma. SSM transforms the bunch into a train of short micro-bunches that resonantly drive high-amplitude wakefields. We use optical transition radiation (OTR) and a streak camera to obtain time-resolved images of the bunch transverse charge density distribution in a given plane. In this paper we present a method to obtain 3D images of the bunch by scanning the OTR across the entrance slit of the streak camera. Reconstruction of the 3D distribution is possible because with seeding self-modulation is reproducible. The 3D images allow for checking the axi-symmetry of SSM and for detecting the possible presence of the non-axi-symmetric hosing instability (HI).
Surrogate-based Bayesian inference of transverse beam distribution for non-stationary accelerator systems
Authors: Fujii H , Fukunishi N , Yamakita M 
Published: January 2023

Abstract
Constraints on the beam diagnostics available in real-time and time-varying beam source conditions make it difficult to provide users with high-quality beams for long periods without interrupting experiments. Although surrogate model-based inference is useful for inferring the unmeasurable, the system states can be incorrectly inferred due to manufacturing errors and neglected higher-order effects when creating the surrogate model. In this paper, we propose to adaptively assimilate the surrogate model for reconstructing the transverse beam distribution with uncertainty and underspecification using a sequential Monte Carlo from the measurements of quadrant beam loss monitors. The proposed method enables sample-efficient and training-free inference and control of the time-varying transverse beam distribution.
Online optimization of NSLS-II dynamic aperture and injection transient
Authors: Yang X , Wang G , Smaluk V , Yu L H , Shaftan T , Li Y , Plassard F , Buda S , Hidaka Y , Durfee D , Tian Y , Hu Y , Ha K , Derbenev A , Bacha B , Danneil C , Padrazo D 
Published: January 2023

Abstract
The goal of the NSLS-II online optimization project is to improve the beam quality for the user experiments. To increase the beam lifetime and injection efficiency, we have developed a model-independent online optimization of nonlinear beam dynamics using advanced algorithms, such as Robust Conjugate-Gradient Algorithm (RCDS). The optimization objective is the injection efficiency and optimization variables are the sextupole magnet strengths. Using the online optimization technique, we increased the NSLS-II dynamic aperture and reduced the amplitude-dependent tune shift. Recently, the sextupole optimization was successfully applied to double the injection efficiency up to above 90% for the high-chromaticity lattice being developed to improve the beam stability and to increase the single-bunch beam intensity. Minimizing the beam perturbation during injection is the second objective in this project, realized by online optimization of the injection kickers. To optimize the full set of kicker parameters, including the trigger timing, amplitude, and pulse width, we upgraded all kicker power supplies with the capability of tunable waveform width. As a result, we have reduced the injection transient by a factor of 29, down to the limit of 60 μm.
Ultra-fast generator for impact ionization triggering
Authors: del Barrio Montañés A A , Senaj V , Kramer T , Dutheil Y , Sack M 
Published: January 2023

Abstract
Impact ionization triggering can be successfully applied to standard thyristors, thus boosting their dI/dt capability by up to 1000x. This ground-breaking triggering requires applying significant overvoltage on the anode-cathode of a thyristor with a slew rate > 1 kV/ns. Compact pulse generators based on commercial off-the-shelf (COTS) components would allow the spread of this technology into numerous applications, including fast kicker generators for particle accelerators. In our approach, the beginning of the triggering chain is an HV SiC MOS with an ultra-fast super-boosting gate driver. The super boosting of a 1.7 kV rated SiC MOS allows to reduce the MOS rise time by a factor of > 26 (datasheet tr = 20 ns vs. measured tr < 800 ps), resulting in an output voltage slew rate > 1 kV/ns and an amplitude > 1 kV. Additional boosting is obtained by a Marx generator with GaAs diodes, reaching an output voltage slew rate > 11 kV/ns. The final stage will be a Marx generator with medium size thyristors triggered in impact ionization mode with sufficient voltage and current rating necessary for the triggering of a high power thyristor. This paper presents the impact ionization triggering of a small size thyristor.