Off-momentum cleaning simulations and measurements at the Large Hadron Collider

Abstract

The Large Hadron Collider is designed to collide proton beams with unprecedented energy in order to extend the frontiers of high-energy physics. Particles that have an energy different from the nominal one follow dispersive orbits and, if the energy offset is large enough, could be lost on the cold aperture and cause quenches of superconducting magnets. Therefore, particles with large energy offsets must be removed from the beam by the collimation system. Although the dynamics of such particles is well understood and the efficiency of the momentum cleaning is evaluated in measurements, in the past, there were not general simulations tools available for predicting the efficiency of the collimation system in scenarios where off-momentum particles are involved. In this paper we present a new set of tools to simulate off-momentum losses, the benchmarking of these tools with measurements and the evaluation of off-momentum losses in the future LHC upgrade, the HL-LHC. These new simulation tools are applied for simulating two of the main scenarios where off-momentum particles play an important role in the LHC: particles lost at the start of the energy ramp and simulations of the momentum cleaning at 6.5 TeV energy. In this study, the collimation process during dynamic changes in the machine is simulated, as opposed to previous studies in static conditions. This is the first time that this sort of comparison between different simulation methods and measurements is performed. The results are used to provide a better understanding the dynamics of such particles and, finally, these tools are used to estimate the influence of off-momentum losses in the future High-Luminosity LHC.