摘要:

At the Large Hadron Collider (LHC) with nominal parameters at 7 TeV, each proton beam has an energy of more than 330 MJ threatening to damage accelerator equipment in case of uncontrolled beam loss. To prevent such damage, kickers are fired in case of failure deflecting the beams into dump blocks. The dump blocks are the only elements that can safely absorb the beams without damage. The time constant for particle losses depends on the specific failure and ranges from microseconds to several seconds. Starting with some typical failure scenarios, the strategy for the protection during LHC beam operation is illustrated. The systems designed to ensure safe operation, such as beam dump, beam instruments, collimators / absorbers and interlocks are discussed. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1638351

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

Dealing with beam loss due to abort kicker prefire is considered for hadron colliders. The prefires occured at Tevatron (Fermilab) during Run I and Run II are analyzed and a protection system implemented is described. The effect of accidental beam loss in the Large Hadron Collider (LHC) at CERN on machine and detector components is studied via realistic Monte Carlo calculations. The simulations show that beam loss at an unsynchronized beam abort would result in severe heating of conventional and superconducting magnets and possible damage to the collider detector elements. A proposed set of collimators would reduce energy deposition effects to acceptable levels. Special attention is paid to reducing peak temperature rise within the septum magnet and minimizing quench region length downstream of the LHC beam abort straight section. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1638352

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

Crystal Channeling occurs when an ion enters a crystal with a small angle with respect to the crystal planes, The electrostatic interaction between the incoming ion and the lattice causes the ion to follow the crystal planes. By mechanically bending a crystal, it is possible to use a crystal to deflect ions. One novel use of a bent crystal is to use it to channel beam halo particles into a collimator downstream. By deflecting the halo particles into a collimator with a crystal it may be possible to improve collimation efficiency as compared to a single collimator. A bent crystal is installed in the yellow ring of the Relativistic Heavy Ion Collider (RHIC). In this paper we discuss our experience with the crystal collimator, and compare our results to previous data, simulation, and theoretical prediction. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1638353

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

Simulation aspects of beam collimation are described along with a number of tools and methods developed and used within themars14 framework. The tools and methods were implemented in order to relieve the burden of simulations needed for reliable calculations required for design of efficient collimation systems at high‐intensity accelerators and colliders. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1638354

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

This report briefly describes studies performed in the framework of the Collimation Task Force organized to support the work of the second International Linear Collider Technical Review Committee. The post‐linac beam‐collimation systems in the TESLA, JLC/NLC and CLIC linear‐collider designs are compared using the same computer code under the same assumptions. Their performance is quantified in terms of beam‐halo and synchrotron‐radiation collimation efficiency. The performance of the current designs varies across projects, and does not always meet the original design goals. But these comparisons suggest that achieving the required performance in a future linear collider is feasible. Further work of the group is briefly described as well. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1638355

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

The collimation system of the Compact Linear Collider (CLIC) must fulfil a number of conflicting requirements, namely it should (1) remove beam halo to reduce the detector background, (2) provide a minimum distance between collimators and collision point for muon suppression, (3) ensure collimator survival and machine protection against errand beam pulses, (4) not be excessively long, and (5) not amplify incoming trajectory fluctuations via the collimator wake fields. Two optical systems have been designed — the first linear, the second non‐linear —, which promise to meet all these requirements for the design beam energy of 1.5 TeV. We decribe the various design criteria, a preliminary performance assessment, and outstanding questions. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1638356

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

To perform a‐proof‐of principle experiment of a SASE based Free Electron Laser a permanent magnet undulator has been installed in the TTF linac phase 1. The magnets used (NdFeB) are known to be sensitive to radiation damages if exposed to high energy electrons. Already beam losses in the order of 10−6of the nominal TTF beam current (64&mgr;A) are critical for the undulator and could have cause an irreversible damage of its magnets after a few months of operation. The protection of the undulator against radiation has been attacked twofold: first, a two stage spoiler‐absorber collimation system has been installed and second, a beam loss detection system of high sensitivity has been added to the machine protection system. The performance and the operational experience of the active and the passive protection system are discussed. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1638357

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

This paper summarizes the presentations and discussions of the Beam‐Beam’03 workshop, held in Montauk, Long Island, from May 19 to 23, 2003. Presentations and discussions focused on halo generation from beam‐beam interactions; beam‐beam limits, especially coherent limits and their effects on existing and future hadron colliders; beam‐beam compensation techniques, particularly for long‐range interactions; and beam‐beam study tools in theory, simulation, and experiment. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1638358

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

Current theoretical understanding of the coherent beam‐beam effect as well as its experimental observations are discussed: conditions under which the coherent beam‐beam modes may appear, possibility of their resonant interaction (coherent resonances), stability of beam‐beam oscillations in the presence of external impedances. A special attention is given to the coherent beam‐beam modes of finite length bunches: the synchro‐betatron coupling is shown to provide reduction in the coherent tuneshift and — at the synchrotron tune values smaller than the beam‐beam parameter — Landau damping by overlapping synchrotron satellites. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1638359

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

Beam‐beam effects in HERA were studied with a self‐consistent beam‐beam simulation by using the particle‐in‐cell method. A remarkable agreement between the experimental measurement and the simulation result was observed on the emittance growth, luminosity reduction, and coherent beam‐beam tune shifts. The simulation study also showed that the chaotic coherent beam‐beam instability could occur in HERA and this collective beam‐beam instability could be avoided with a slightly different tune. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1638360

出版商:AIP    

年代:1903

数据来源: AIP