Abstracts Brochure - CERN

TUPLS018
TUPLS019
TUPLS020
27-Jun-06 16:00 - 18:00 TUPLS — Poster Session
LHC Collimation Efficiency during Commissioning
C.B. Bracco, R.W. Assmann, A. Ferrari, S. Redaelli, G. Robert-
Demolaize, M. Santana-Leitner, V. Vlachoudis, Th. Weiler (CERN)
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The design of the LHC collimation system
naturally focused on understanding and
maximizing the ultimate performance with
all collimators in place. However, for the
commissioning of the LHC it is important to analyze the collimation efficiency with certain subsets of collimators,
with increased collimation gaps and relaxed set-up tolerances. Special studies on halo tracking and energy deposition
have been performed in order to address this question. The expected cleaning performance and intensity limits are
discussed for various collimation scenarios as they might be used during commissioning and initial operation of the
LHC.
Critical Halo Loss Locations in the LHC
G. Robert-Demolaize, R.W. Assmann, C.B. Bracco, S. Redaelli, Th.
Weiler (CERN)
The requirements on cleaning efficiency in
the LHC are two to three orders of magnitude
beyond the needs at existing super-conducting
colliders. The LHC will therefore operate
in unknown territory, which can only be assessed by powerful simulation tools. Such tools have been developed at
CERN over the last years, making it possible to perform detailed simulations of the LHC cleaning processes and
multi-turn loss patterns around the LHC ring. The simulation includes all collimators, diluters and absorbers in
the LHC. Proton loss maps are generated with a 10 cm resolution, which allows performing advanced studies for
quenches of super-conducting magnets along with the analysis of the deposited energy in the machine elements. The
critical locations of beam halo losses are discussed, both for the ideal machine and for various scenarios of closedorbit
distortion and beta-beating. From these results it can be shown that it is sufficient to use a limited number of
BLM’s for the setup and optimization of the LHC collimation system.
Simulations for the Protection of Warm and Superconducting Elements at IR7 Insertion of
LHC
The beam cleaning insertion IR7 of the fu-
M. Santana-Leitner (CERN)
ture Large Hadron Collider (LHC), collimates
part of the primary beam halo as well
as the secondary radiation. The transverse energy and intensity carried by the beam lays three orders of magnitude
above the values of current facilities, thereby requiring careful calculations of the heat deposition in the collimators
and in other fragile units. This report includes a detailed study of the energy deposition in the coils of the most
critical magnets. Special attention is paid to the coil insulators, where a dose surpassing 4 MGy/y could start to
severely reduce the lifetime of the magnet. The project inherits the complex geometry layout and beam loss input
used for previous shielding studies and inserts passive absorber blocks in key positions to maintain the doses below
breakup threshold. Finally, the tertiary halo is tracked through the passive absorbers down to the cold arc through
the formerly optimized active absorber scheme, in order to verify that no quenches take place in the superconducting
coils.