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Title: Interaction point backgrounds from the CLIC post collision line
Author: Salt, Michael David
ISNI:       0000 0004 2729 7246
Awarding Body: University of Manchester
Current Institution: University of Manchester
Date of Award: 2012
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The proposed CLIC accelerator is designed to collide electrons and positrons at a centre of mass energy of 3 TeV, and a luminosity of 5.9 x 10^(34) cm^(−2) s^(−1) at the interaction point (IP). Being a single-pass machine, luminosity must be maximised by minimising the beam spot size to the order of a few nanometres. The effects of the final focussing and the intense beam-beam effects lead to a high production cross section of beamstrahlung photons, and highly divergent outgoing beams, both spatially and in energy. Pair-production of the beamstrahlung photons leads to coherent pairs. The proposed CLIC post-collision line must transport electrons, positrons and photons from the IP to their respective dumps with minimal losses and background contribution. It is favourable to separate the particle species for diagnostic purposes, and thus the proposed post-collision line contains vertically bending magnets to separate based on charge. This process introduces dispersion to the energetically divergent beam, requiring the vertical apertures of the accelerator components to increase with distance from the IP. Particles in the low energy extreme of the beam cannot realistically pass through the components, which must therefore be protected by carbon-based absorbers. Losses in these absorbers and in the various dumps of the accelerator lead to electromagnetic showering within the material, some of which may be directed onto the IP. Optimisation of the apertures and positions of these components is presented as original research in this thesis. It is the purpose of this thesis to study the CLIC post-collision line, beam transport and the production and effects of secondary particles at the IP. Primarily, the backscattered photons are evaluated, with an introduction to the effect of neutrons. Photonsincident on silicon detectors have the potential to produce false hits, and neutrons to degrade the detectors. The effect of losses on the accelerator components is studied and the survivability of these components discussed.
Supervisor: Appleby, Robert Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: CLIC ; Post-Collision