An improved scattering routine for collimation tracking studies at LHC

The present Master thesis work has been carried out at CERN in the framework of the LHC (Large Hadron Collider) Collimation project. The LHC accelerates proton beams up to 7 TeV colliding in the experiment detectors installed in four points of the accelerator ring. The LHC is built to store a energy of 360MJ for each beam. The energy deposition induced by local beam losses could quench the superconducting magnets located around the accelerator beam pipes. To prevent and keep under control dangerous beam losses, an efficient collimation system is required. In addition, the achievable LHC beam intensity is related to the beam loss rate and, consequently, to the cleaning efficiency of the collimation system. Collimation studies at LHC are carried out also by means of simulations by using SixTrack, a dedicated simulation tool that tracks a large numbers of particles for many turns around the ring. The SixTrack code includes a scattering routine to model proton interactions with the material of the collimators jaws. It is based on a Monte Carlo method that simulates the nuclear and the electromagnetic processes between the incoming proton and the collimator material nuclei. This study presents an update of this routine by using new recent experimental data to better describe the interaction processes at higher energy. In order to introduce effective modifications able to provide a better approximation of the experimental data a deep investigation on the physics model underlying the scattering routine has been carried out. As result of this study several changes have been considered and then implemented in the scattering routine regarding both the electromagnetic and nuclear processes. The effects of the changes are also taken into account by means of comparison between experimental data and simulations at 3.5 TeV proton energy. In addition, simulations with the updated routine at 7 TeV proton energy are performed and the collimation cleaning efficiency investigated. These results will be provided as an input for collimation studies at higher energy.