Six UK institutes are engaged in a collaborative R&D programme with CERN aimed at demonstrating key aspects of technology feasibility for the Compact Linear Collider (CLIC). We give an overview and status of: 1) Drive-beam components:... more
Six UK institutes are engaged in a collaborative R&D programme with CERN aimed at demonstrating key aspects of technology feasibility for the Compact Linear Collider (CLIC). We give an overview and status of: 1) Drive-beam components: quadrupole magnets and the beam phase feed-forward prototype. 2) Beam instrumentation: stripline and cavity beam position monitors, an electro-optical longitudinal bunch profile monitor, and laserwire and diffraction and transition radiation monitors for transverse beam-size determination. 3) Beam delivery system and machinedetector interface design, including beam feedback/control systems and crab cavity design and control. 4) RF structure design. In each case we report on the status of prototype systems and performance tests with beam at the CTF3, ATF2 and CESRTA test facilities, including plans for future experiments.
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In 2017, AWAKE demonstrated the seeded self-modulation (SSM) of a 400 GeV proton beam from the Super Proton Synchrotron at CERN. The angular distribution of the protons deflected due to SSM is a quantitative measure of the process, which... more
In 2017, AWAKE demonstrated the seeded self-modulation (SSM) of a 400 GeV proton beam from the Super Proton Synchrotron at CERN. The angular distribution of the protons deflected due to SSM is a quantitative measure of the process, which agrees with simulations by the two-dimensional (axisymmetric) particle-in-cell code LCODE to about 5%. The agreement is achieved in beam population scans at two selected plasma densities and in the scan of longitudinal plasma density gradient. The agreement is reached only in the case of a wide enough simulation box (several plasma wavelengths) that is closer to experimental conditions, but requires more computational power. Therefore, particle-in-cell codes can be used to interpret the SSM physics underlying the experimental data.
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SIGLEAvailable from British Library Document Supply Centre- DSC:3642.46(EATL/M--2659) / BLDSC - British Library Document Supply CentreGBUnited Kingdo
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The ILC Crab Cavity is positioned close to the IP and delivered luminosity is very sensitive to the wakefields induced in it by the beam. A set of couplers were designed to couple to and damp the spurious modes of the crab cavity. As the... more
The ILC Crab Cavity is positioned close to the IP and delivered luminosity is very sensitive to the wakefields induced in it by the beam. A set of couplers were designed to couple to and damp the spurious modes of the crab cavity. As the crab cavity operates using a dipole mode, it has different damping requirements from an accelerating cavity. A separate coupler is required for the monopole modes below the operating frequency of 3.9 GHz (known as the LOMs), the opposite polarization of the operating mode (the SOM), and the modes above the operating frequency (the HOMs). Prototypes of each of these couplers have been manufactured out of copper and measured attached to an aluminum nine cell prototype of the cavity and their external Q factors were measured. The results were found to agree well with numerical simulations.
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A large crossing angle ( ~ 20 mrad) for electron and positron bunches through the beam delivery system of International Linear Collider (ILC) is currently a favoured option of the Global Design Effort (GDE). For crossing angles greater... more
A large crossing angle ( ~ 20 mrad) for electron and positron bunches through the beam delivery system of International Linear Collider (ILC) is currently a favoured option of the Global Design Effort (GDE). For crossing angles greater than about 2 mrad, matching crab cavity systems are required on the electron and positron beam lines to impart an angular kick to the bunches so that they become aligned at the interaction point (I.P.). The avoidance of differential transverse deflection of electron and positron bunches at the I.P. requires almost perfect matching of the RF phase of the crab cavity system on the positron beam line to the crab cavity system on the electron beam line. In this paper the effects of phase and amplitude errors in the ILC crab cavity have been calculated, and these have been used to estimate the tolerances on the crab system.
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Effect of altering the cavity shape in infinitely periodic dipole cavities
The International Linear Collider (ILC) has a 14 mrad crossing angle in order to aid extraction of spent bunches. As a result of the bunch shape at the interaction point, this crossing angle at the collision causes a large luminosity loss... more
The International Linear Collider (ILC) has a 14 mrad crossing angle in order to aid extraction of spent bunches. As a result of the bunch shape at the interaction point, this crossing angle at the collision causes a large luminosity loss which can be recovered by rotating the bunches prior to collision using a crab cavity. The ILC baseline crab cavity is a 9-cell superconducting dipole cavity operating at a frequency of 3.9 GHz. In this paper the design of the ILC crab cavity and its phase control system, as selected for the RDR 1 in February 2007 is described in fuller detail. 1.
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R. Calaga , A. Alekou, F. Antoniou, R. B. Appleby, L. Arnaudon, K. Artoos, G. Arduini, V. Baglin, S. Barriere, H. Bartosik, P. Baudrenghien, I. Ben-Zvi, T. Bohl, A. Boucherie, O. S. Brüning, K. Brodzinski, A. Butterworth, G. Burt, O.... more
R. Calaga , A. Alekou, F. Antoniou, R. B. Appleby, L. Arnaudon, K. Artoos, G. Arduini, V. Baglin, S. Barriere, H. Bartosik, P. Baudrenghien, I. Ben-Zvi, T. Bohl, A. Boucherie, O. S. Brüning, K. Brodzinski, A. Butterworth, G. Burt, O. Capatina, S. Calvo, T. Capelli, M. Carlà, F. Carra, L. R. Carver, A. Castilla-Loeza, E. Daly, L. Dassa, J. Delayen, S. U. De Silva, A. Dexter, M. Garlasche, F. Gerigk, L. Giordanino, D. Glenat, M. Guinchard, A. Harrison, E. Jensen, C. Julie, T. Jones, F. Killing, A. Krawczyk, T. Levens, R. Leuxe, B. Lindstrom, Z. Li, A. MacEwen, A. Macpherson, P. Menendez, T. Mikkola, P. Minginette, J. Mitchell, E. Montesinos, G. Papotti, H. Park, C. Pasquino, S. Pattalwar, E. C. Pleite, T. Powers, B. Prochal, A. Ratti, L. Rossi, V. Rude, M. Therasse, R. Tomás, N. Stapley, I. Santillana, N. Shipman, J. Simonin, M. Sosin, J. Swieszek, N. Templeton, G. Vandoni, S. Verdú-Andrés, M. Wartak, C. Welsch, D. Wollman, Q. Wu, B. Xiao, E. Yamakawa, C. Zanoni, F. Zimmermann, and A....
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Crab cavities have been proposed for a wide number of accelerators and interest in crab cavities has recently increased after the successful operation of a pair of crab cavities in KEK-B. In particular crab cavities are required for both... more
Crab cavities have been proposed for a wide number of accelerators and interest in crab cavities has recently increased after the successful operation of a pair of crab cavities in KEK-B. In particular crab cavities are required for both the ILC and CLIC linear colliders for bunch alignment. Consideration of bunch structure and size constraints favour a 3.9 GHz superconducting, multi-cell cavity as the solution for ILC, whilst bunch structure and beam-loading considerations suggest an X-band copper travelling wave structure for CLIC. These two cavity solutions are very different in design but share complex design issues. Phase stabilisation, beam loading, wakefields and mode damping are fundamental issues for these crab cavities. Requirements and potential design solutions will be discussed for both colliders.
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Plasma wakefield dynamics over timescales up to 800 ps, approximately 100 plasma periods, are studied experimentally at the Advanced Wakefield Experiment (AWAKE). The development of the longitudinal wakefield amplitude driven by a... more
Plasma wakefield dynamics over timescales up to 800 ps, approximately 100 plasma periods, are studied experimentally at the Advanced Wakefield Experiment (AWAKE). The development of the longitudinal wakefield amplitude driven by a self-modulated proton bunch is measured using the external injection of witness electrons that sample the fields. In simulation, resonant excitation of the wakefield causes plasma electron trajectory crossing, resulting in the development of a potential outside the plasma boundary as electrons are transversely ejected. Trends consistent with the presence of this potential are experimentally measured and their dependence on wakefield amplitude are studied via seed laser timing scans and electron injection delay scans.
A precise characterization of the incoming proton bunch parameters is required to accurately simulate the self-modulation process in the Advanced Wakefield Experiment (AWAKE). This paper presents an analysis of the parameters of the... more
A precise characterization of the incoming proton bunch parameters is required to accurately simulate the self-modulation process in the Advanced Wakefield Experiment (AWAKE). This paper presents an analysis of the parameters of the incoming proton bunches used in the later stages of the AWAKE Run 1 data-taking period. The transverse structure of the bunch is observed at multiple positions along the beamline using scintillating or optical transition radiation screens. The parameters of a model that describes the bunch transverse dimensions and divergence are fitted to represent the observed data using Bayesian inference. The analysis is tested on simulated data and then applied to the experimental data.
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The Compact Linear Collider (CLIC) is a multi-TeV high-luminosity linear e+e- collider under development. For an optimal exploitation of its physics potential, CLIC is foreseen to be built and operated in a staged approach with three... more
The Compact Linear Collider (CLIC) is a multi-TeV high-luminosity linear e+e- collider under development. For an optimal exploitation of its physics potential, CLIC is foreseen to be built and operated in a staged approach with three centre-of-mass energy stages ranging from a few hundred GeV up to 3 TeV. The first stage will focus on precision Standard Model physics, in particular Higgs and top-quark measurements. Subsequent stages will focus on measurements of rare Higgs processes, as well as searches for new physics processes and precision measurements of new states, e.g. states previously discovered at LHC or at CLIC itself. In the 2012 CLIC Conceptual Design Report, a fully optimised 3 TeV collider was presented, while the proposed lower energy stages were not studied to the same level of detail. This report presents an updated baseline staging scenario for CLIC. The scenario is the result of a comprehensive study addressing the performance, cost and power of the CLIC accelerat...
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The beam requirements result from the known parameters of the LHC upgrade lattice and the expected LHC beam parameters at ultimate bunch intensity. There are boundary conditions imposed by certain beam parameters such as the bunch length... more
The beam requirements result from the known parameters of the LHC upgrade lattice and the expected LHC beam parameters at ultimate bunch intensity. There are boundary conditions imposed by certain beam parameters such as the bunch length and intensity and by the machine ...
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Deflecting cavities are used in particle accelerators for the manipulation of charged particles by deflecting or crabbing (rotating) them. For short deflectors, the effect of the power coupler on the deflecting field can become... more
Deflecting cavities are used in particle accelerators for the manipulation of charged particles by deflecting or crabbing (rotating) them. For short deflectors, the effect of the power coupler on the deflecting field can become significant. The particular power coupler type can introduce multipole rf field components and coupler-specific wakefields. Coupler types that would normally be considered like standard on-cell coupler, waveguide coupler, or mode-launcher coupler could have one or two rf feeds. The major advantage of a dual-feed coupler is the absence of monopole and quadrupole rf field components in the deflecting structure. However, a dual-feed coupler is mechanically more complex than a typical single-feed coupler and needs a splitter. For most applications, deflecting structures are placed in regions where there is small space hence reducing the size of the structure is very desirable. This paper investigates the multipole field components of the deflecting mode in single...
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G. Burt 1 , P. Ambattu 1 , P. Goudket 2 , B. Hall 1 , P. McIntosh 2 , A. Dexter 1 , C. Beard 1,2 , I. Tahir 1 , R. ... Carter 1 , R. Jones 3 , M. Dykes 2 , A. Kalinin 2 , L. Ma 2 , ... 1 Cockcroft Institute, Lancaster University,... more
G. Burt 1 , P. Ambattu 1 , P. Goudket 2 , B. Hall 1 , P. McIntosh 2 , A. Dexter 1 , C. Beard 1,2 , I. Tahir 1 , R. ... Carter 1 , R. Jones 3 , M. Dykes 2 , A. Kalinin 2 , L. Ma 2 , ... 1 Cockcroft Institute, Lancaster University, Lancaster, UK, LA1 4YR 2 ASTeC, Daresbury Laboratory, ...
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Neutrino oscillations have implications for the Standard Model of particle physics. The CERN Beta Beam has outstanding capabilities to contribute to precision measurements of the parameters governing neutrino oscillations. The FP7... more
Neutrino oscillations have implications for the Standard Model of particle physics. The CERN Beta Beam has outstanding capabilities to contribute to precision measurements of the parameters governing neutrino oscillations. The FP7 collaboration EUROnu (2008-2012) is a design study that will review three facilities (Super-Beams, Beta Beams and Neutrino Factories) and perform a cost assessment that, coupled with the physics performance,
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... [5] The MAFIA Collaboration, CST GmbH, Darmstadt, 1994 [online] http://www.cst.com/. [6] G. Burt, Analysis of Damping Requirements for Dipole Wake-Fields in RF Crab Cavities, Vol 54, Issue 5, Part 2 of TNS (October 2007) [7] P.... more
... [5] The MAFIA Collaboration, CST GmbH, Darmstadt, 1994 [online] http://www.cst.com/. [6] G. Burt, Analysis of Damping Requirements for Dipole Wake-Fields in RF Crab Cavities, Vol 54, Issue 5, Part 2 of TNS (October 2007) [7] P. Goudket, Impedance Measurements on a Test ...
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A. Seryi † , J. Amann, R. Arnold, F. Asiri, K. Bane, A. Fasso, L. Keller, K. Ko, Z. Li, T. Markiewicz, T. Maruyama, K. Moffeit, S. Molloy, Y. Nosochkov, S. Smith, C. Spencer, P. Tenenbaum, D. Walz, G. White, M. Woodley, M. Woods, ...