LHC Collimation: Design and Results from Prototyping and Beam Tests

Abstract

The problem of collimation and beam cleaning is one of the most challenging aspects of the LHC project. A collimation system must be designed, built, installed and commissioned with parameters that extend the present state-of-the-art by 2-3 orders of magnitude. Problems include robustness, cleaning efficiency, impedance and operational aspects. A strong design effort has been performed at CERN over the last two years. The adopted phased approach is described. Robust and precisely controllable collimators have been designed. Several LHC prototype collimators have been built and tested with the highest beam intensities that are presently available at CERN. The successful beam tests are presented, including beam-based setup procedures, a 2 MJ robustness test and measurements of the collimator-induced impedance. Finally, an outlook is presented on the challenges that are ahead in the coming years. Large Hadron Collider Project AbstractThe problem of collimation and beam cleaning is one of the most challenging aspects of the LHC project. A collimation system must be designed, built, installed and commissioned with parameters that extend the present state-of-the-art by 2-3 orders of magnitude. Problems include robustness, cleaning efficiency, impedance and operational aspects. A strong design effort has been performed at CERN over the last two years. The adopted phased approach is described. Robust and precisely controllable collimators have been designed. Several LHC prototype collimators have been built and tested with the highest beam intensities that are presently available at CERN. The successful beam tests are presented, including beam-based setup procedures, a 2 MJ robustness test and measurements of the collimator-induced impedance. Finally, an outlook is presented on the challenges that are ahead in the coming years.

The LHC collimator controls architecture - design and beam tests

“…The beam experiments included (1) tests with circulating proton beams at the SPS, performed with the full scale collimator prototype already used in 2004 [7], and (2) tests with extracted LHC-type beams in the TT40 line during a collimator material robustness experiment.…”

Geometric efficiency of a two-stage fully absorbing collimation system in single-pass linacs

“…Collimation systems are used both on linear [2][3][4][5][6][7] and on circular accelerators [8][9][10] to minimize background in physics detectors, to avoid quench magnets in superconducting machines, and to limit the irradiation of equipment, possibly leading to demagnetization of undulator permanent magnets. The need of high luminosities in colliders and in linac-based free electron lasers (FELs) obtained with high beam intensities makes these problems even more serious.…”

“…Particle tracking plays a role also in [7,8,17] where the inefficiency c is defined as the ratio of the number N i ðA cut Þ of particles traveling at amplitudes larger than the cut amplitude A cut over the number N imp of particles impacting the collimator; A cut is given by the vacuum chamber aperture downstream of the CS:…”

Performance of the CERN SPS Fast Extraction for the CNGS Facility

“…After the implementation of the modifications described above the kicker system was re-commissioned in spring 2004 and used during periods of CNGS low intensity extraction, the commissioning of the new LHC transfer line TI 8 and the LHC collimator tests [5][6][7]. The kick field was measured with capacitive pick-ups (permitting a kick measurement in the SPS) and an inductive probe (as a field calibration reference, not useable in the SPS Step 2" after adding magnet damping resistors (laboratory result), "…”