KIT, Karlsruhe
CERN, Geneva
NCP, Islamabad
Fermilab, Batavia
We report about generic halo and tail simulations and estimates. Previous studies were mainly focused on very high energies as relevant for the beam delivery systems of linear colliders. We have now studied, applied and extended these simulations to lower energies as relevant for the CLIC drive beam.
CERN, Geneva
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
IN2P3-LAPP, Annecy-le-Vieux
DESY, Hamburg
SLAC, Menlo Park, California
The CLIC BDS is experiencing the careful revision from a large number of world wide experts. This was particularly enhanced by the successful CLIC'08 workshop held at CERN. Numerous new ideas, improvements and critical points are arising, establishing the path towards the Conceptual Design Report by 2010.
CERN, Geneva
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
IHEP Beijing, Beijing
LAL, Orsay
KEK, Ibaraki
UMAN, Manchester
SLAC, Menlo Park, California
The CLIC Final Focus System has considerably larger chromaticity than those of ILC and its scaled test machine ATF2. We propose to reduce the IP betas of ATF2 to reach a CLIC-like chromaticity. This would also allow to study the FFS tuning difficulty as function of the IP beam spot size. Both the ILC and CLIC projects will largely benefit from the ATF2 experience at these ultra-low IP betas.
CERN, Geneva
NSC/KIPT, Kharkov
IN2P3 IPNL, Villeurbanne
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
LAL, Orsay
ANL, Argonne
KEK, Ibaraki
HU/AdSM, Higashi-Hiroshima
BNL, Upton, Long Island, New York
Hiroshima University, Graduate School of Science, Higashi-Hiroshima
The CLIC polarized positron source is based on a positron production scheme in which polarized photons are produced by Compton process. Compton backscattering happens in a so-called "Compton ring" where an electron beam of 1.06 GeV interacts with a powerful laser beam amplified in an optical resonator. The circularly-polarized gamma rays are sent on to a target, producing pairs of longitudinally polarized electrons and positrons. An Adiabatic Matching Device maximizes the capture of the positrons. A normal-conducting 2 GHz Linac accelerates the beam up to 2.424 GeV before injection into the Pre-Damping Ring (PDR). The nominal CLIC bunch population is 4.4x109 particles per bunch. Since the photon flux coming out from a "Compton ring" is not sufficient to obtain the requested charge, a stacking process is required in the PDR. Another option is to use a "Compton Energy Recovery Linac" where a quasi-continual stacking in the PDR could be achieved. A third option is to use a "Compton Linac" which would not require stacking. We describe the overall scheme as well as advantages and constraints of the three different options.
Ankara University, Faculty of Engineering, Tandogan, Ankara
CERN, Geneva
Funding: Turkish Atomic Energy Authority
CLIC study aims at a center-of-mass energy for electron-positron collisions of 3TeV using room temperature accelerating structures at high frequency (12GHz) which are likely to achieve 100 MV/m gradient. Due to conventional high frequency RF sources do not provide sufficient RF power for 100MV/m gradient, CLIC relies upon a two-beam-acceleration concept: The 12GHz RF power is generated by a high current electron beam (Drive Beam) running parallel to the main beam with deceleration in special Power Extraction Structures (PETS) and the generated RF power is transferred to the main beam. In order to obtain very high RF power at 12GHz frequency, injected beam into PETS should have 2.37GeV energy, 101A pulse current and pulse length around 240ns. Drive beam accelerator (DBA) accelerates the beam up to 2.37GeV in almost fully-loaded structures and the pulse after DBA contains more than 70000 bunches, has a length around 140μs and 4.2A pulse current. After some modifications in delay loop and in combiner rings the beam has 101A pulse current and 240ns pulse length. In this study simulations of some transverse beam parameters for different options for the lattice of the DBA are presented.
IHEP Beijing, Beijing
CERN, Geneva
A new design of the 6.6GeV Booster linac for CLIC which is based on the FODO lattice is presented in this note. Particle tracking studies using PLACET [1] are performed in order to estimate the single-bunch and multi-bunch emittance growth. First, the studies of optics are introduced. Then, the sing-bunch effects and multi-bunch effects are studied in the last two part of this note.
CERN, Geneva
In the main linac of the compact linear collider (CLIC) the beam induced wakefield and dispersive effects will be strong. In the paper the reference beam-based alignment procedure for the new CLIC parameters is specified and the resulting tolerances for static imperfections are detailed.
CERN, Geneva
In the compact linear collider (CLIC) the tolerances on dynamic imperfections are tight in the main linac. In particular the limited beam delivery system bandwidth requires very good RF phase and amplitude stability. Transverse motion of the beam line components is also of concern. The resulting tolerances are detailed in the paper.
CERN, Geneva
Uppsala University, Uppsala
Fermilab, Batavia
Prior to acceleration in the main linac, the particle beams created in the centrally located injector have to be transported to the outer ends of the CLIC site. This transport should not only preserve the beam quality but also shape, characterize and tune the phase space distribution to match the requirements at the entrance of the main linac. Hence, the performance of the transport downstream of the damping rings up to the main linac, the so called RTML, is crucial for the overall performance of CLIC. The RTML consists of a variety of components like bunch compressors, accelerating cavities, spin rotators, collimators, diagnostics sections, feedback and feedforward systems, each serving a distinct function. We discuss the different parts of the RTML and the beam dynamics challenges connected to them. Their status is outlined and results of beam dynamics simulations are presented.
CERN, Geneva
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
The emission of Synchrotron Radiation in the CLIC BDS is one of the major limitations of the machine performance. An extensive revision of this phenomenon is presented with special emphasis on the IP solenoid.
CERN, Geneva
The specification for vacuum pressure in the CLIC electron Main Linac critically depends on the fast ion instability. In fact, the maximum tolerable pressure value in the pipe of the Main Linac is dictated by the threshold above which the fast ion instability sets in over a CLIC bunch train. Previous calculation based on ion generation from residual gas ionization alone showed that, due to the loss of the trapping along the linac caused by the beam size shrinking from acceleration, a pressure as high as 10 nTorr could be accepted, higher than the tolerable value in the long transfer line. However, since the accelerated beam becomes transversely very small, its electric field can reach values above the field ionization threshold. When this happens, the whole space region with a sufficiently high electric field gets instantly fully ionized by the first bunch and the effect on the bunch train could be severe. We have modeled field ionization in our simulation code FASTION and re-evaluated the onset of fast ion instability in the Main Linac.
CERN, Geneva
In the main linac of the compact linear collider (CLIC) , wakefield induced multi-bunch effects are important. They have a strong impact on the choice of accelerating structure design. The paper presents the limit for the wakefield that one bunch exerts on the next. It also gives estimates for the allowed level of persistent wake fields and on the resistive wall wakefield.
SLAC, Menlo Park, California
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
JAI, Oxford
KEK, Ibaraki
IHEP Beijing, Beijing
LAL, Orsay
Royal Holloway, University of London, Surrey
IN2P3-LAPP, Annecy-le-Vieux
OXFORDphysics, Oxford, Oxon
ATOMKI, Debrecen
CERN, Geneva
DESY, Hamburg
Fermilab, Batavia
Kyungpook National University, Daegu
PAL, Pohang, Kyungbuk
Kyoto ICR, Uji, Kyoto
ICEPP, Tokyo
University of Tokyo, Tokyo
UCL, London
BNL, Upton, Long Island, New York
Tohoku University, Graduate School of Science, Sendai
UMAN, Manchester
Hiroshima University, Graduate School of Science, Higashi-Hiroshima
Cockcroft Institute, Warrington, Cheshire
ATF2 is a final-focus test beam line that attempts to focus the low-emittance beam from the ATF damping ring to a beam size of about 37 nm, and at the same time to demonstrate nm beam stability, using numerous advanced beam diagnostics and feedback tools. The construction is well advanced and beam commissioning of ATF2 has started in the second half of 2008. ATF2 is constructed and commissioned by ATF international collaborations with strong US, Asian and European participation.
CERN, Geneva
N.U, Nigde
Cockcroft Institute, Warrington, Cheshire
Ankara University, Faculty of Sciences, Tandogan/Ankara
The University of Liverpool, Liverpool
KEK, Ibaraki
TOBB ETU, Ankara
BNL, Upton, Long Island, New York
Sub-atomic physics at the energy frontier probes the structure of the fundamental quanta of the Universe. The Large Hadron Collider (LHC) at CERN opens for the first time the “terascale” (TeV energy scale) to experimental scrutiny, exposing the physics of the Universe at the sub-attometric (~10-19 m, 10-10 as) scale. The LHC will also take the science of nuclear matter to hitherto unparalleled energy densities (low-x physics). The hadron beams, protons or ions, in the LHC underpin this horizon, and also offer new experimental possibilities at this energy scale. A Large Hadron electron Collider, LHeC, in which an electron (positron) beam of energy (70 to 140 GeV) is in collision with one of the LHC hadron beams, makes possible terascale lepton-hadron physics. The LHeC is presently being evaluated in the form of two options, “ring-ring” and “linac-ring”, either of which operate simultaneously with pp or ion-ion collisions in other LHC interaction regions. Each option takes advantage of recent advances in radio-frequency, in linear acceleration, and in other associated technologies, to achieve ep luminosity as large as 1033 cm-2s-1.