Development of beam transverse profile and emittance monitors for the CERN LINAC 4

LINAC4 is part of the CERN Large Hadron Collider injector chain upgrade (LIU) and will accelerate H− ions from 45 keV to 160 MeV, it will be the first step of the upgrade with the replacement of LINAC2 in 2018. In order to measure beam profiles along the LINAC, several SEM grid and wire beam scanner (WS) monitors will be installed between the RF cavities from 50 MeV to 160 MeV. This thesis covers all monitor design aspects intended to cope with the required specifications. In particular, the overall measurement robustness, accuracy and sensitivity must be satisfied for different commissioning and operational scenarios. The physics mechanisms generating the wire signals and the wire resistance to beam induced thermal loads have been considered in order to determine the most appropriate monitor design in terms of wire material and dimensions. In addition, for the commissioning phase, a movable diagnostics test bench will be used to adjust the machine parameters during different stages of installation. One of the main instruments on this movable bench is a transverse emittance meter. This thesis presents the different studies done for the mechanical design of the slit and for the estimation of the systematical error on the measurement due to space charge and multiple scattering. To complete this section, the first results of the commissioning of the LINAC4 ions source and LEBT are presented, together with results form emittance measurement taken at the Spallation Neutron Source in Oak Ridge (Tennessee, USA). This last part ot the thesis presents different studies done for a beam profiles and emittance measurements with a laser wire, with a large input from the SNS beam diagnostic group. te l-0 07 00 60 6, v er si on 1 23 M ay 2 01 2