Physical Review Special Topics-accelerators and Beams最新文献

{"title":"First measurement and correction of nonlinear errors in the experimental insertions of the CERN Large Hadron Collider","authors":"E. Maclean, R. Tomás, M. Giovannozzi, T. Persson","doi":"10.1103/PHYSREVSTAB.18.121002","DOIUrl":"https://doi.org/10.1103/PHYSREVSTAB.18.121002","url":null,"abstract":"Nonlinear magnetic errors in low-β insertions can contribute significantly to detuning with amplitude, linear and nonlinear chromaticity, and lead to degradation of dynamic aperture and beam lifetime. As such, the correction of nonlinear errors in the experimental insertions of colliders can be of critical significance for successful operation. This is expected to be of particular relevance to the LHC’s second run and its high luminosity upgrade, as well as to future colliders such as the Future Circular Collider. Current correction strategies envisioned for these colliders assume it will be possible to calculate optimized local corrections through the insertions, using a magnetic model of the errors. This paper shows however, that reliance purely upon magnetic measurements of the nonlinear errors of insertion elements is insufficient to guarantee a good correction quality in the relevant low-β � regime. It is possible to perform beam-based examination of nonlinear magnetic errors via the feed-down to readily observed beam properties upon application of closed orbit bumps, and methods based upon feed-down to tune have been utilized at RHIC, SIS18, and SPS. This paper demonstrates the extension of such methodology to include direct observation of feed-down to linear coupling in the LHC. It is further shown that such beam-based studies can be used to complement magnetic measurements performed during LHC construction, in order to validate and refine the magnetic model of the collider. Results from first attempts of the measurement and correction of nonlinear errors in the LHC experimental insertions are presented. Several discrepancies of beam-based studies with respect to the LHC magnetic model are reported.","PeriodicalId":20072,"journal":{"name":"Physical Review Special Topics-accelerators and Beams","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89530301","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Compensation of the long-range beam-beam interactions as a path towards new configurations for the high luminosity LHC","authors":"S. Fartoukh, A. Valishev, Y. Papaphilippou, D. Shatilov","doi":"10.1103/PHYSREVSTAB.18.121001","DOIUrl":"https://doi.org/10.1103/PHYSREVSTAB.18.121001","url":null,"abstract":"Colliding bunch trains in a circular collider demands a certain crossing angle in order to separate the two beams transversely after the collision. The magnitude of this crossing angle is a complicated function of the bunch charge, the number of long-range beam-beam interactions, of β* and type of optics (flat or round), and possible compensation or additive effects between several low-β insertions in the ring depending on the orientation of the crossing plane at each interaction point. About 15 years ago, the use of current bearing wires was proposed at CERN in order to mitigate the long-range beam-beam effects [J. P. Koutchouk, CERN Report No. LHC-Project-Note 223, 2000], therefore offering the possibility to minimize the crossing angle with all the beneficial effects this might have: on the luminosity performance by reducing the need for crab-cavities or lowering their voltage, on the required aperture of the final focus magnets, on the strength of the orbit corrector involved in the crossing bumps, and finally on the heat load and radiation dose deposited in the final focus quadrupoles. In this paper, a semianalytical approach is developed for the compensation of the long-range beam-beam interactions with current wires. This reveals the possibility of achieving optimal correction through a careful adjustment of the aspect ratio of the β functions at the wire position. We consider the baseline luminosity upgrade plan of the Large Hadron Collider (HL-LHC project), and compare it to alternative scenarios, or so-called “configurations,” where modifications are applied to optics, crossing angle, or orientation of the crossing plane in the two low-β insertions of the ring. For all these configurations, the beneficial impact of beam-beam compensation devices is then demonstrated on the tune footprint, the dynamical aperture, and/or the frequency map analysis of the nonlinear beam dynamics as the main figures of merit.","PeriodicalId":20072,"journal":{"name":"Physical Review Special Topics-accelerators and Beams","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75031597","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Volume reflection and volume capture of ultrarelativistic particles in bent single crystals","authors":"S. Bellucci, Y. Chesnokov, V. Maisheev, I. Yazynin","doi":"10.1103/PHYSREVSTAB.18.114701","DOIUrl":"https://doi.org/10.1103/PHYSREVSTAB.18.114701","url":null,"abstract":"The paper is devoted to the study of volume reflection and volume capture of high energy particles moving in planar fields of bent single crystals. The influence of volume capture on the process of volume reflection was considered analytically. Relations describing various distributions of particles involved in the process, the probability of volume capture and the behavior of channeling and dechanneling fractions of a beam were obtained. Results of the study will be useful in the realization of multicrystal devices for collimation and extraction of beams on modern and future accelerators.","PeriodicalId":20072,"journal":{"name":"Physical Review Special Topics-accelerators and Beams","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89271952","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Simple modification of Compton polarimeter to redirect synchrotron radiation","authors":"J. Benesch, G. Franklin, B. Quinn, K. Paschke","doi":"10.1103/PHYSREVSTAB.18.112401","DOIUrl":"https://doi.org/10.1103/PHYSREVSTAB.18.112401","url":null,"abstract":"Synchrotron radiation produced as an electron beam passes through a bending magnet is a significant source of background in many experiments. Using modeling, we show that simple modifications of the magnet geometry can reduce this background by orders of magnitude in some circumstances. Specifically, we examine possible modifications of the four dipole magnets used in Jefferson Lab’s Hall A Compton polarimeter chicane. This Compton polarimeter has been a crucial part of experiments with polarized beams and the next generation of experiments will utilize increased beam energies, up to 11 GeV, requiring a corresponding increase in Compton dipole field to 1.5 T. In consequence, the synchrotron radiation (SR) from the dipole chicane will be greatly increased. Three possible modifications of the chicane dipoles are studied; each design moves about 2% of the integrated bending field to provide a gentle bend in critical regions along the beam trajectory which, in turn, greatly reduces the synchrotron radiation within the acceptance of the Compton polarimeter photon detector. Each of the modifications studied also softens the SR energy spectrum at the detector sufficiently to allow shielding with 5 mm of lead. Simulations show that these designs are each capable of reducing the background signal duemore » to SR by three orders of magnitude. The three designs considered vary in their need for vacuum vessel changes and in their effectiveness.« less","PeriodicalId":20072,"journal":{"name":"Physical Review Special Topics-accelerators and Beams","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85009701","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Conceptual designs of two petawatt-class pulsed-power accelerators for high-energy-density-physics experiments","authors":"W. Stygar, T. Awe, J. E. Bailey, N. Bennett, E. Breden, E. M. Campbell, R. E. Clark, R. A. Cooper, M. Cuneo, J. B. Ennis, D. Fehl, T. Genoni, M. R. Gomez, G. Greiser, F. Gruner, M. C. Herrmann, B. Hutsel, C. A. Jennings, D. Jobe, B. M. Jones, M. C. Jones, P. A. Jones, P. F. Knapp, J. Lash, K. LeChien, J. Leckbee, R. Leeper, S. Lewis, F. Long, D. Lucero, E. Madrid, M. R. Martin, M. Matzen, M. Mazarakis, R. D. McBride, G. R. McKee, C. Miller, J. K. Moore, C. Mostrom, T. Mulville, K. Peterson, J. L. Porter, D. Reisman, G. Rochau, G. Rochau, D. Rose, D. Rovang, M. E. Savage, M. Sceiford, P. Schmit, R. F. Schneider, J. Schwarz, A. Sefkow, D. Sinars, S. Slutz, R. Spielman, B. Stoltzfus, C. Thoma, R. Vesey, P. Wakeland, D. Welch, M. Wisher, J. Woodworth","doi":"10.1103/PHYSREVSTAB.18.110401","DOIUrl":"https://doi.org/10.1103/PHYSREVSTAB.18.110401","url":null,"abstract":"Here, we have developed conceptual designs of two petawatt-class pulsed-power accelerators: Z 300 and Z 800. The designs are based on an accelerator architecture that is founded on two concepts: single-stage electrical-pulse compression and impedance matching [Phys. Rev. ST Accel. Beams 10, 030401 (2007)]. The prime power source of each machine consists of 90 linear-transformer-driver (LTD) modules. Each module comprises LTD cavities connected electrically in series, each of which is powered by 5-GW LTD bricks connected electrically in parallel. (A brick comprises a single switch and two capacitors in series.) Six water-insulated radial-transmission-line impedance transformers transport the power generated by the modules to a six-level vacuum-insulator stack. The stack serves as the accelerator’s water-vacuum interface. The stack is connected to six conical outer magnetically insulated vacuum transmission lines (MITLs), which are joined in parallel at a 10-cm radius by a triple-post-hole vacuum convolute. The convolute sums the electrical currents at the outputs of the six outer MITLs, and delivers the combined current to a single short inner MITL. The inner MITL transmits the combined current to the accelerator’s physics-package load. Z 300 is 35 m in diameter and stores 48 MJ of electrical energy in its LTD capacitors. The acceleratormore » generates 320 TW of electrical power at the output of the LTD system, and delivers 48 MA in 154 ns to a magnetized-liner inertial-fusion (MagLIF) target [Phys. Plasmas 17, 056303 (2010)]. The peak electrical power at the MagLIF target is 870 TW, which is the highest power throughout the accelerator. Power amplification is accomplished by the centrally located vacuum section, which serves as an intermediate inductive-energy-storage device. The principal goal of Z 300 is to achieve thermonuclear ignition; i.e., a fusion yield that exceeds the energy transmitted by the accelerator to the liner. 2D magnetohydrodynamic (MHD) simulations suggest Z 300 will deliver 4.3 MJ to the liner, and achieve a yield on the order of 18 MJ. Z 800 is 52 m in diameter and stores 130 MJ. This accelerator generates 890 TW at the output of its LTD system, and delivers 65 MA in 113 ns to a MagLIF target. The peak electrical power at the MagLIF liner is 2500 TW. The principal goal of Z 800 is to achieve high-yield thermonuclear fusion; i.e., a yield that exceeds the energy initially stored by the accelerator’s capacitors. 2D MHD simulations suggest Z 800 will deliver 8.0 MJ to the liner, and achieve a yield on the order of 440 MJ. Z 300 and Z 800, or variations of these accelerators, will allow the international high-energy-density-physics community to conduct advanced inertial-confinement-fusion, radiation-physics, material-physics, and laboratory-astrophysics experiments over heretofore-inaccessible parameter regimes.« less","PeriodicalId":20072,"journal":{"name":"Physical Review Special Topics-accelerators and Beams","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81548703","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High power test of an injector linac for heavy ion cancer therapy facilities","authors":"L. Lu, T. Hattori, Huanyu Zhao, K. Kawasaki, Liangting Sun, Yuan He, Hongwei Zhao","doi":"10.1103/PHYSREVSTAB.18.111002","DOIUrl":"https://doi.org/10.1103/PHYSREVSTAB.18.111002","url":null,"abstract":"A hybrid single cavity (HSC) linac, combined with radio frequency quadrupole and drift tube structure in a single interdigital-H cavity, operates with high rf power as a prototype injector for cancer therapy synchrotron. The HSC adopts a direct plasma injection scheme (DPIS) with a laser ion source. The input beam current of the HSC is designed to be 20 mA ${mathrm{C}}^{6+}$ ions. According to simulations, the HSC can accelerate a 6-mA ${mathrm{C}}^{6+}$ beam which meets the requirement of the particle number for cancer therapy ($1{0}^{8ensuremath{sim}9}text{ }text{ions}/text{pulse}$). The HSC injector with DPIS makes the existing multiturn injection system and stripping system unnecessary; what is more, it can also bring down the size of the beam pipe in existing synchrotron magnets, which can reduce the whole cost of the synchrotron. Details of the field measurements of the HSC linac and results of the high power test are reported in this paper.","PeriodicalId":20072,"journal":{"name":"Physical Review Special Topics-accelerators and Beams","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73552517","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cyclotron radiation cooling of a short electron bunch kicked in an undulator with guiding magnetic field","authors":"I. Bandurkin, I. Osharin, A. Savilov","doi":"10.1103/PHYSREVSTAB.18.110702","DOIUrl":"https://doi.org/10.1103/PHYSREVSTAB.18.110702","url":null,"abstract":"We propose to use of an undulator with the guiding axial magnetic field as a ``kicker'' forming a bunch of electron gyro-oscillators with a small spread in the axial velocity. The cyclotron emission from the bunch leads to losing oscillatory velocity of electron gyrorotation, but it does not perturb the axial electron velocity. This effect can be used for transformation of minimization of the spread in electron axial velocity in the undulator section into minimization of the spread in electron energy in the cyclotron radiation section.","PeriodicalId":20072,"journal":{"name":"Physical Review Special Topics-accelerators and Beams","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86897502","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Polarization of x-gamma radiation produced by a Thomson and Compton inverse scattering","authors":"V. Petrillo, A. Bacci, C. Curatolo, I. Drebot, A. Giribono, C. Maroli, A. Rossi, L. Serafini, P. Tomassini, C. Vaccarezza, A. Variola","doi":"10.1103/PHYSREVSTAB.18.110701","DOIUrl":"https://doi.org/10.1103/PHYSREVSTAB.18.110701","url":null,"abstract":"V. Petrillo, A. Bacci, C. Curatolo, I. Drebot, A. Giribono, C. Maroli, A. R. Rossi, L. Serafini, P. Tomassini, C. Vaccarezza, and A. Variola Università degli Studi di Milano, via Celoria 16, 20133 Milano, Italy INFN-Sezione di Milano, via Celoria 16, 20133 Milano, Italy INFN Laboratori Nazionali di Frascati,Via E. Fermi 44, 00044 Frascati, Roma, Italy Università La Sapienza, Via Antonio Scarpa, 14 00161 Roma, Italy and INFN-Roma1, Piazzale Aldo Moro, 2 00161 Rome, Italy (Received 24 June 2015; published 19 November 2015)","PeriodicalId":20072,"journal":{"name":"Physical Review Special Topics-accelerators and Beams","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85686765","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Long bunch trains measured using a prototype cavity beam position monitor for the Compact Linear Collider","authors":"F. Cullinan, S. Boogert, W. Farabolini, T. Lefevre, A. Lunin, A. Lyapin, L. Soby, J. Towler, M. Wendt","doi":"10.1103/PHYSREVSTAB.18.112802","DOIUrl":"https://doi.org/10.1103/PHYSREVSTAB.18.112802","url":null,"abstract":"electromagnetic resonant modes excited by the beam in the two cavities of the pickup, the position cavity and the reference cavity. The mode that is measured in each cavity resonates at 15 GHz and has a loaded quality factor that is below 200. Analytical expressions for the amplitude, phase and total energy of signals from long trains of bunches have been derived and the main conclusions are discussed. The results of the beam tests are presented. The variable gain of the receiver electronics has been characterized using beam excited signals and the form of the signals for different beam pulse lengths with the 2=3 ns bunch spacing has been observed. The sensitivity of the reference cavity signal to charge and the horizontal position signal to beam offset have been measured and are compared with theoretical predictions based on laboratory measurements of the BPM pickup and the form of the resonant cavity modes as determined by numerical simulation. Finally, the BPM was calibrated so that the beam position jitter at the BPM location could be measured. It is expected that the beam jitter scales linearly with the beam size and so the results are compared to predicted values for the latter.","PeriodicalId":20072,"journal":{"name":"Physical Review Special Topics-accelerators and Beams","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75122640","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Design of the large hadron electron collider interaction region","authors":"E. Cruz-Alaniz, D. Newton, R. Tomás, M. Korostelev","doi":"10.1103/PHYSREVSTAB.18.111001","DOIUrl":"https://doi.org/10.1103/PHYSREVSTAB.18.111001","url":null,"abstract":"The large hadron electron collider (LHeC) is a proposed upgrade of the Large Hadron Collider (LHC) within the high luminosity LHC (HL-LHC) project, to provide electron-nucleon collisions and explore a new regime of energy and luminosity for deep inelastic scattering. The design of an interaction region for any collider is always a challenging task given that the beams are brought into crossing with the smallest beam sizes in a region where there are tight detector constraints. In this case integrating the LHeC into the existing HL-LHC lattice, to allow simultaneous proton-proton and electron-proton collisions, increases the difficulty of the task. A nominal design was presented in the the LHeC conceptual design report in 2012 featuring an optical configuration that focuses one of the proton beams of the LHC to β∗=10 cm in the LHeC interaction point to reach the desired luminosity of L=1033 cm−2 s−1. This value is achieved with the aid of a new inner triplet of quadrupoles at a distance L∗=10 m from the interaction point. However the chromatic beta beating was found intolerable regarding machine protection issues. An advanced chromatic correction scheme was required. This paper explores the feasibility of the extension of a novel optical technique called the achromatic telescopic squeezing scheme and the flexibility of the interaction region design, in order to find the optimal solution that would produce the highest luminosity while controlling the chromaticity, minimizing the synchrotron radiation power and maintaining the dynamic aperture required for stability.","PeriodicalId":20072,"journal":{"name":"Physical Review Special Topics-accelerators and Beams","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80745577","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}