Beam Collimation at Hadron Colliders

Mokhov, N.

doi:10.1063/1.1638313

Cited by 10 publications

(14 citation statements)

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“…Suppressing the out-scattered particles can be quite difficult. A more sophisticated way to handle the out-scattered particles is to go to a two-stage collimation system 1 . A thin primary target is used to scatter the beam out by increasing the amplitude of the betatron oscillations of the halo particles and thereby increasing the impact parameters on to secondary collimators during the next turns without influencing the unscattered beam.…”

Section: The Challenge Of Collider Collimationmentioning

confidence: 99%

<title>Channeling collimation studies at the Fermilab Tevatron</title>

et al. 2007

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Bent crystal channeling has promising advantages for accelerator beam collimation at high energy hadron facilities such as the LHC. This significance has been amplified by several surprising developments including multi-pass channeling and the observation of enhanced deflections over the entire arc of a bent crystal. The second effect has been observed both at RHIC and recently at the Tevatron. Results are reported showing channeling collimation of the circulating proton beam halo at the Tevatron. Parenthetically, this study is the highest energy proton channeling experiment ever carried out. The study is continuing.Keywords: Channeling, collimation, accelerator, Tevatron THE CHALLENGE OF COLLIDER COLLIMATIONDuring the design of the Superconducting Super Collider (SSC) it was recognized that collimating the intense proton beams required for high luminosity posed daunting challenges. A halo develops around any circulating beam due to many effects such as beam-gas and beam-beam interactions. Superconducting magnets can be quenched or destroyed if they scrape even a tiny portion of the beam. Collider detector devices such as silicon strip detectors are even more sensitive.In so-called single stage conventional collimation the beam halo is scraped by a collimator moved into the halo. Typically the collimator is a 1.5 m long block of steel or other medium or high-Z material. A certain fraction of the halo will survive, either by traversing the length of the collimator or by scattering out of the collimator block. Suppressing the out-scattered particles can be quite difficult. A more sophisticated way to handle the out-scattered particles is to go to a two-stage collimation system 1 . A thin primary target is used to scatter the beam out by increasing the amplitude of the betatron oscillations of the halo particles and thereby increasing the impact parameters on to secondary collimators during the next turns without influencing the unscattered beam.At the SSC, Mokhov and his colleagues 2 proposed an innovative solution to the collimation problem. In their arrangement an aligned, bent single crystal is used to deflect the beam out into a collimator much as a magnetic septum would. However, using the crystal results in a much higher deflection per unit length with little effective septum width. Since the SSC design there have been several developments that have made crystal collimation even more promising. One was a fuller understanding of so-called crystal multi-pass extraction first observed at CERN 3 . The other was the development of several approaches at the Institute for High Energy Physics (IHEP) and the Petersburg Nuclear Physics Institute (PNPI) for producing very short crystal bending lengths characteristically using anticlastic crystal deformations 4 . In view of the promise for both extraction and collimation the SSC sponsored a research program on crystal extraction at the Tevatron. That experiment, E853 5 , showed that extraction was possible in the context of a superconducting accelerator. FERMILA...

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Section: The Challenge Of Collider Collimationmentioning

confidence: 99%

<title>Channeling collimation studies at the Fermilab Tevatron</title>

et al. 2007

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“…Halo transverse diffusion velocities in Colliders are typically in the range of 1.5 micron/sec [2] which is on the order of 10 6 smaller than due to motion of an un-captured particle. The small transverse diffusion velocity in Colliders give rise to impact parameters of .1 to .15 micron.…”

Section: Imapct Parametermentioning

confidence: 99%

“…This difference in momentum between the un-captured beam and the change in momentum of the captured beam due to the ramp is given by (2) where p u is the momentum of the un-captured particle and p c is the momentum of the synchronous particle during the ramp. The time dependence of this momentum deviation is determined by the MI ramp structure.…”

Section: Uncaptured Beammentioning

confidence: 99%

“…The creation of non-zero dispersion in a long straight section could lead to increased collimation efficieny and momentum selectiveness for either a two stage collimation scheme [2] or a single stage collimation scheme.…”

Section: Utility For Collimationmentioning

confidence: 99%

“…In the Tevatron, the impact parameter grows linearly with transverse difusion velocity. [2] ) ( ) ( )…”

Section: Imapct Parametermentioning

confidence: 99%

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A dynamic dispersion insert in the Fermilab Main Injector for momentum collimation

Johnson

2007

2007 IEEE Particle Accelerator Conference (PAC)

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The Fermilab Main Injector (MI) accelerator is designed as a FODO lattice with zero dispersion straight sections. A scheme will be presented that can dynamically alter the dispersion of one of the long straight sections to create a non-zero dispersion straight section suitable for momentum collimation. During the process of slip stacking DC beam is generated which is lost during the first few milliseconds of the ramp. A stationary massive primary collimator/absorber with optional secondary masks could be utilized to isolate beam loss due to uncaptured beam. MAIN INJECTOR LATTICE Ring LatticeThe MI is 3.3 km in circumference and was designed as a pure FODO lattice with eight dispersion free straight sections of either 3, 4, or 8 half-cells in length.

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