Physical Review Accelerators and Beams最新文献

{"title":"From Compton scattering of photons on targets to inverse Compton scattering of electron and photon beams","authors":"Luca Serafini, Vittoria Petrillo","doi":"10.1103/physrevaccelbeams.27.080701","DOIUrl":"https://doi.org/10.1103/physrevaccelbeams.27.080701","url":null,"abstract":"We revisit the kinematics of Compton scattering (electron-photon interactions producing electrons and photons in the exit channel) covering the full range of energy/momenta distribution between the two colliding particles, with a dedicated view to statistical properties of secondary beams that are generated in beam-beam collisions. Starting from the Thomson inverse scattering, where electrons do not recoil and photons are backscattered to higher energies by a Lorentz boost effect (factor <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mn>4</mn><msup><mi>γ</mi><mn>2</mn></msup></math>), we analyze three transition points, separating four regions. These are in sequence, given by increasing the electron recoil (numbers are for transition points and letters for regions): (a) Thomson backscattering, (1) equal sharing of total energy in the exit channel between electron and photon, (b) deep recoil regime where the bandwidth/energy spread of the two interacting beams are exchanged in the exit channel, (2) electron is stopped, i.e., taken down at rest in the laboratory system by colliding with an incident photon of <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>m</mi><msup><mi>c</mi><mn>2</mn></msup><mo>/</mo><mn>2</mn></math> energy, (c) electron backscattering region, where incident electron is backscattered by the incident photon, and (3) symmetric scattering, when the incident particles carry equal and opposite momenta, so that in the exit channel they are backscattered with same energy/momenta, and (d) Compton scattering [<i>ála</i> Arthur Compton, see A. J. Compton, A quantum theory of the scattering of X-rays by light elements, <span>Phys. Rev.</span> <b>21</b>, 83 (1923)], where photons carry an energy much larger than the colliding electron energy. For each region and/or transition point, we discuss the potential effects of interest in diverse areas, like generating monochromatic gamma-ray beams in deep recoil regions with spectral purification, or possible mechanisms of generation and propagation of very high energy photons in the cosmological domain.","PeriodicalId":54297,"journal":{"name":"Physical Review Accelerators and Beams","volume":"4 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142177727","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Machine-learning approach for operating electron beam at KEK electron/positron injector linac","authors":"Gaku Mitsuka, Shinnosuke Kato, Naoko Iida, Takuya Natsui, Masanori Satoh","doi":"10.1103/physrevaccelbeams.27.084601","DOIUrl":"https://doi.org/10.1103/physrevaccelbeams.27.084601","url":null,"abstract":"In current accelerators, numerous parameters and monitored values are to be adjusted and evaluated, respectively. In addition, fine adjustments are required to achieve the target performance. Therefore, the conventional accelerator-operation method, in which experts manually adjust the parameters, is reaching its limits. We are currently investigating the use of machine learning for accelerator tuning as an alternative to expert-based tuning. In recent years, machine-learning algorithms have progressed significantly in terms of speed, sensitivity, and application range. In addition, various libraries are available from different vendors and are relatively easy to use. Herein, we report the results of electron-beam tuning experiments using Bayesian optimization, a tree-structured Parzen estimator, and a covariance matrix-adaptation evolution strategy. Beam-tuning experiments are performed at the KEK <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msup><mi>e</mi><mo>−</mo></msup><mo>/</mo><msup><mi>e</mi><mo>+</mo></msup></math> injector Linac to maximize the electron-beam charge and reduce the energy-dispersion function. In each case, the performance achieved is comparable to that of a skilled expert.","PeriodicalId":54297,"journal":{"name":"Physical Review Accelerators and Beams","volume":"1 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142177728","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Excitation of nonlinear second order betatron sidebands for knock-out slow extraction at the third-integer resonance","authors":"Philipp Niedermayer, Rahul Singh","doi":"10.1103/physrevaccelbeams.27.082801","DOIUrl":"https://doi.org/10.1103/physrevaccelbeams.27.082801","url":null,"abstract":"Radio frequency knock out resonant slow extraction is a standard method for extracting stored particle beams from synchrotrons by transverse excitation. Classically, the beam is excited with an rf field comprising a frequency band around one of the betatron sidebands. This article demonstrates that the third-integer resonance commonly used for the slow extraction induces nonlinear motion, resulting in the appearance of additional sidebands of higher order at multiples of the betatron tune. Measured and simulated beam spectra are presented, revealing these sidebands and the beam’s response to being excited at first and second order sidebands. The feasibility of using a second order sideband for the purpose of slow extraction is demonstrated. This results in a significant improvement in the temporal structure (spill quality) of the extracted beam, but at the cost of higher excitation power requirements. This is observed both experimentally and in tracking simulations. The mechanism behind the observed improvement is explained using beam dynamics simulations.","PeriodicalId":54297,"journal":{"name":"Physical Review Accelerators and Beams","volume":"16 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142177739","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Continuous Electron Beam Accelerator Facility at 12 GeV","authors":"P. A. Adderleyet al.","doi":"10.1103/physrevaccelbeams.27.084802","DOIUrl":"https://doi.org/10.1103/physrevaccelbeams.27.084802","url":null,"abstract":"This review paper describes the energy-upgraded Continuous Electron Beam Accelerator Facility (CEBAF) accelerator. This superconducting linac has achieved 12 GeV beam energy by adding 11 new high-performance cryomodules containing 88 superconducting cavities that have operated cw at an average accelerating gradient of <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>20</mn><mtext> </mtext><mtext> </mtext><mi>MV</mi><mo>/</mo><mi mathvariant=\"normal\">m</mi></mrow></math>. After reviewing the attributes and performance of the previous 6 GeV CEBAF accelerator, we discuss the upgraded CEBAF accelerator system in detail with particular attention paid to the new beam acceleration systems. In addition to doubling the acceleration in each linac, the upgrade included improving the beam recirculation magnets, adding more helium cooling capacity to allow the newly installed modules to run cold, adding a new experimental hall, and improving numerous other accelerator components. We review several of the techniques deployed to operate and analyze the accelerator performance and document system operating experience and performance. In the final portion of the document, we present much of the current planning regarding projects to improve accelerator performance and enhance operating margins, and our plans for ensuring CEBAF operates reliably into the future. For the benefit of potential users of CEBAF, the performance and quality measures for the beam delivered to each of the experimental halls are summarized in the Appendix.","PeriodicalId":54297,"journal":{"name":"Physical Review Accelerators and Beams","volume":"2 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142177540","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fabrication and testing of the transition section between modules of a wakefield accelerator","authors":"A. Zholents, S. Lee, B. Popovic, M. Fedurin, K. Kusche, W. Li, A. Nassiri, A. Siy, S. Sorsher, K. Suthar, E. Trakhtenberg, G. Waldschmidt","doi":"10.1103/physrevaccelbeams.27.081303","DOIUrl":"https://doi.org/10.1103/physrevaccelbeams.27.081303","url":null,"abstract":"The fabrication process is presented for a typical transition section located between each cylindrical corrugated waveguide structure comprising the wakefield accelerator module. The transition section includes couplers for extracting the 180 GHz <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mrow><mi>TM</mi></mrow><mrow><mn>01</mn></mrow></msub></mrow></math> accelerating mode and separate couplers for extracting the 190 GHz <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mrow><mi>HE</mi></mrow><mrow><mn>11</mn></mrow></msub></mrow></math> dipole mode, both modes induced by the electron bunch traversing the cylindrical corrugated waveguide structure. Extraction of the high-power accelerating mode reduces the heat load due to the subterahertz wave power dissipation within the corrugated accelerating structure. Extraction of the low-power dipole mode serves the purpose of detecting the electron bunch transverse oscillations within the wakefield accelerator and identifying the onset of beam breakup instability. Comprehensive testing of the fully functional transition section with an electron beam was done at the Accelerator Test Facility in Brookhaven National Laboratory which verified the functionality of the transition section.","PeriodicalId":54297,"journal":{"name":"Physical Review Accelerators and Beams","volume":"9 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142177741","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Collimator challenges at SuperKEKB and their countermeasures using nonlinear collimator","authors":"Shinji Terui, Yoshihiro Funakoshi, Takuya Ishibashi, Haruyo Koiso, Mika Masuzawa, Yu Morikawa, Akio Morita, Shu Nakamura, Hiroyuki Nakayama, Yukiyoshi Ohnishi, Kazuhito Ohmi, Kyo Shibata, Mitsuru Shirai, Yusuke Suetsugu, Makoto Tobiyama, Ryuichi Ueki, Demin Zhou, Katsunobu Oide, Andrii Natochii","doi":"10.1103/physrevaccelbeams.27.081001","DOIUrl":"https://doi.org/10.1103/physrevaccelbeams.27.081001","url":null,"abstract":"In SuperKEKB, movable collimators reduce the beam background noise in the Belle II particle detector and protect crucial machine components, such as final focusing superconducting quadrupole magnets (QCS), from abnormal beam losses. The challenges related to the collimator, which were not properly considered at the time of SuperKEKB design, have surfaced through experience with its operation. In this paper, we report the collimator operation strategy in SuperKEKB. In addition, a significant challenge of beam collimation due to the future increase in the beam background is highlighted. We also discuss another issue caused by unexpected and sudden beam losses in the machine that damage collimators, leading to weaker beam collimation performance and an increase in transverse impedance. Furthermore, we introduce a novel collimation approach called the nonlinear collimator (NLC) to address these challenges. We detail the concept of NLC and evaluate their effectiveness by assessing the collimator impedance, beam background reduction, and impact on the dynamic aperture. The possibility of using NLCs as absorber collimators to counteract events that damage the collimator is also shown to be helpful.","PeriodicalId":54297,"journal":{"name":"Physical Review Accelerators and Beams","volume":"9 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142177742","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Benchmarking of hydrodynamic plasma waveguides for multi-GeV laser-driven electron acceleration","authors":"B. Miao, E. Rockafellow, J. E. Shrock, S. W. Hancock, D. Gordon, H. M. Milchberg","doi":"10.1103/physrevaccelbeams.27.081302","DOIUrl":"https://doi.org/10.1103/physrevaccelbeams.27.081302","url":null,"abstract":"Hydrodynamic plasma waveguides initiated by optical field ionization have recently become a key component of multi-GeV laser wakefield accelerators. Here, we present the most complete and accurate experimental and simulation-based characterization to date, applicable to current multi-GeV experiments and future 100 GeV-scale laser plasma accelerators. Crucial to the simulations is the correct modeling of intense Bessel beam interaction with meter-scale gas targets, the results of which are used as initial conditions for hydrodynamic simulations. The simulations are in good agreement with our experiments measuring evolving plasma and neutral hydrogen density profiles using two-color short pulse interferometry, enabling realistic determination of the guided mode structure for application to laser-driven plasma accelerator design.","PeriodicalId":54297,"journal":{"name":"Physical Review Accelerators and Beams","volume":"43 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142177740","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Electron diffusion in microbunched electron cooling","authors":"W. F. Bergan","doi":"10.1103/physrevaccelbeams.27.084402","DOIUrl":"https://doi.org/10.1103/physrevaccelbeams.27.084402","url":null,"abstract":"Coherent electron cooling is a novel method to cool dense hadron beams on timescales of a few hours. This method uses a copropagating beam of electrons to pick up the density fluctuations within the hadron beam in one straight section and then provides corrective energy kicks to the hadrons in a downstream straight, cooling the beam. Microbunched electron cooling is an extension of this idea, which induces a microbunching instability in the electron beam as it travels between the two straights, amplifying the signal. However, initial noise in the electron bunch will also be amplified, providing random kicks to the hadrons downstream which tend to increase their emittance. In this paper, we develop an analytic estimate of the effect of the electron noise and benchmark it against simulations. We also discuss how this effect has impacted the cooler design.","PeriodicalId":54297,"journal":{"name":"Physical Review Accelerators and Beams","volume":"5 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141943783","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Demonstration of high-efficiency microwave heating producing record highly charged xenon ion beams with superconducting electron cyclotron resonance ion sources","authors":"X. Wang, J. B. Li, V. Mironov, J. W. Guo, X. Z. Zhang, O. Tarvainen, Y. C. Feng, L. X. Li, J. D. Ma, Z. H. Zhang, W. Lu, S. Bogomolov, L. Sun, H. W. Zhao","doi":"10.1103/physrevaccelbeams.27.083401","DOIUrl":"https://doi.org/10.1103/physrevaccelbeams.27.083401","url":null,"abstract":"Intense highly charged ion beam production is essential for high-power heavy ion accelerators. A novel movable Vlasov launcher for superconducting high charge state electron cyclotron resonance ion source has been devised that can affect the microwave power effectiveness by a factor of about 4 in terms of highly charged ion beam production. This approach based on a dedicated microwave launching system instead of the traditional coupling scheme has led to new insight on microwave-plasma interaction. With this new understanding, the world record highly charged xenon ion beam currents have been enhanced by up to a factor of 2, which could directly and significantly enhance the performance of heavy ion accelerators and provide many new research opportunities in nuclear physics, atomic physics, and other disciplines.","PeriodicalId":54297,"journal":{"name":"Physical Review Accelerators and Beams","volume":"23 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141943909","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Bayesian optimization algorithms for accelerator physics","authors":"Ryan Rousselet al.","doi":"10.1103/physrevaccelbeams.27.084801","DOIUrl":"https://doi.org/10.1103/physrevaccelbeams.27.084801","url":null,"abstract":"Accelerator physics relies on numerical algorithms to solve optimization problems in online accelerator control and tasks such as experimental design and model calibration in simulations. The effectiveness of optimization algorithms in discovering ideal solutions for complex challenges with limited resources often determines the problem complexity these methods can address. The accelerator physics community has recognized the advantages of Bayesian optimization algorithms, which leverage statistical surrogate models of objective functions to effectively address complex optimization challenges, especially in the presence of noise during accelerator operation and in resource-intensive physics simulations. In this review article, we offer a conceptual overview of applying Bayesian optimization techniques toward solving optimization problems in accelerator physics. We begin by providing a straightforward explanation of the essential components that make up Bayesian optimization techniques. We then give an overview of current and previous work applying and modifying these techniques to solve accelerator physics challenges. Finally, we explore practical implementation strategies for Bayesian optimization algorithms to maximize their performance, enabling users to effectively address complex optimization challenges in real-time beam control and accelerator design.","PeriodicalId":54297,"journal":{"name":"Physical Review Accelerators and Beams","volume":"197 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141943784","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}