MSci Project Proposal Form 2010-2011
Project Code: HEP-Hall-1
Project title: LHC Beam Collimation using crystal channeling
Supervisor:
Prof. G. Hall
Assessor: Dr. M. Raymond
Telephone: x47800
Telephone: x 47799
E-mail:
E-mail: m.raymond@imperial.ac.uk
g.hall@imperial.ac.uk
Research Group: HEP
Research Group: HEP
Project Summary:
The CERN Large Hadron Collider has recently started operation. It aims to reach a luminosity (the
interaction rate per unit of cross-section) of 1034 cm-2.s-1, and this is crucial to obtain the event
statistics needed to investigate the physics in the TeV energy range. The present machine can
probably achieve 1033 cm-2.s-1 but to get beyond that requires improvement in the collimation system,
which “cleans” the proton beams so that halo particles do not impinge on the superconducting
magnets and cause them to quench (i.e. revert to a normal conducting state). This is a far from trivial
issue because multi-TeV protons cannot be absorbed easily and they undergo various types of
interaction process in mechanical collimators which scatter them into the downstream magnets.
One of the most promising techniques to improve this is to take advantage of a phenomenon known
as “crystal channelling”. In a highly symmetric crystal lattice, charged particles can propagate along
the planes separating the fixed nuclei in a confining potential well and experience much less
scattering than normal. By bending the crystal, protons can be steered utilising the enormous electric
field within the crystal. The phenomenon has been used for some years to extract beams from the
synchrotron in Protvino, Russia, where most of the theory has been developed. However, the
experimental results which would allow this to be utilised at the LHC are so far insufficient. Such
things as dependence on proton energy, crystal dimensions and quality, tolerance to high radiation
levels, mechanical and thermal tolerances need careful characterisation.
A project is under way in CERN to study this more systematically and already shown promising
results. Later this year, a significant period of data taking will be allocated to beam tests with a
readout system which will be provided by the Imperial College CMS group. There should be a
significant amount of data to analyse from October 2010.
The project work should include developing a sound understanding of the physics of crystal
channelling, understanding the essential experimental equipment used to take data, gaining expertise
with computing tools needed to look at the data and analysis of the data. If it can be agreed with the
department, it is possible that an opportunity to visit CERN to see the experiment and participate in
collaboration meetings could be arranged.
Experimental component: 33%
Computational component: 33%
Theoretical component:
33%
Is the MSci Project eligible for students on the MSci
Physics with Theoretical Physics Degree It could be considered.
Suggested reading (at least one relevant reference):
V Biryukov, Y. Chesnokov, V . Kotov. Crystal channelling and Its Application at High Energy Accelerators.
Springer 1997 (available from Imperial College Library)
W. Scandale et al. Apparatus to study crystal channeling and volume reflection phenomena at the SPS H8
beamline. Review of Scientific Instruments 79, 023303 2008
V Biryukov et al. Crystal collimation as an option for the large hadron colliders. Nuclear Instruments and
Methods in Physics Research B 234 (2005) 23–30
Imperial College of Science, Technology, and Medicine