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Abstracts Brochure - CERN

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MOPLS — Poster Session 26-Jun-06 16:00 - 18:00<br />

thresholds for quenches. Further simulations of beam losses caused by collimation and electromagnetic interactions<br />

peculiar to heavy ion collisions determine the positions of extra BLMs needed for ion operation in the LHC.<br />

Beam Halo on the LHC TCDQ Diluter System and Thermal Load on the Downstream Superconducting<br />

Magnets<br />

The moveable single-jawed graphite TCDQ<br />

diluter must be positioned very close to the<br />

circulating LHC beam in order to prevent<br />

damage to downstream components in the<br />

B. Goddard, R.W. Assmann, A. Presland, S. Redaelli, G. Robert-<br />

Demolaize, L. Sarchiapone, Th. Weiler, W.J.M. Weterings (<strong>CERN</strong>)<br />

event of an unsynchronised beam abort. A two-jawed graphite TCS collimator forms part of the TCDQ system. The<br />

requirement to place the TCDQ and TCS jaws close to the beam means that the system can intercept a substantial<br />

beam halo load. Initial investigations indicated a worryingly high heat load on the Q4 coils. This paper presents the<br />

updated load cases, shielding and simulation geometry, and the results of simulations of the energy deposition in the<br />

TCDQ system and in the downstream superconducting Q4 magnet. The implications for the operation of the LHC<br />

are discussed.<br />

The LHC as a Proton-nucleus Collider<br />

Following its initial operation as a proton-proton<br />

(p-p) and heavy-ion (208Pb J.M. Jowett, C. Carli (<strong>CERN</strong>)<br />

82+ -<br />

208Pb 82+ ) collider, the LHC is expected to<br />

operate as a p-Pb collider. Later it may collide protons with other lighter nuclei such as 40Ar 18+ or 16O 8+ . We show<br />

how the existing proton and lead-ion injector chains may be efficiently operated in tandem to provide these hybrid<br />

collisions. The two-in-one magnet design of the LHC main rings imposes different revolution frequencies for the two<br />

beams in part of the magnetic cycle. We discuss and evaluate the consequences for beam dynamics and estimate the<br />

potential performance of the LHC as a proton-nucleus collider.<br />

Measurement of Ion Beam Losses Due to Bound-free Pair Production in RHIC<br />

When the LHC operates as a Pb 82+ ion collider,<br />

losses of Pb 81+ ions, created through<br />

Bound-free Pair Production (BFPP) at the collision<br />

point, and localized in cold magnets,<br />

J.M. Jowett, S.S. Gilardoni (<strong>CERN</strong>) R. Bruce (MAX-lab) K.A. Drees,<br />

W. Fischer, S. Tepikian (BNL) S.R. Klein (LBNL)<br />

are expected to be a major luminosity limit. With Au 79+ ions at RHIC, this effect is not a limitation because the Au 78+<br />

production rate is low, and the Au 78+ beam produced is inside the momentum aperture. When RHIC collided Cu 29+<br />

ions, secondary beam production rates were lower still but the Cu 28+ ions produced were predicted to be lost at a welldefined<br />

location, creating the opportunity for the first direct observation of BFPP effects in an ion collider. We report<br />

on measurements of localized beam losses due to BFPP with copper beams in RHIC and comparisons to predictions<br />

from tracking and Monte Carlo simulation.<br />

109<br />

MOPLS008<br />

MOPLS009<br />

MOPLS010

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