ELECTRON TRACKING SIMULATIONS IN THE PRESENCE OF THE BEAM AND EXTERNAL FIELDS

The ionisation profile monitors installed in the CERN LHC and SPS make use of the ionisation of a small volume of the injected neon gas by the circulating beam. The electrons produced are guided towards the readout system using a combination of electric and magnetic fields. In the presence of the beam field their tracks are modified and the resulting profile is distorted. The Geant4 particle simulation package has been used to simulate the ionisation process, while the CERN developed PyECLOUD code has been used for tracking of the resulting ionised particles. In this paper the results of simulations are compared with observations and conclusions are presented concerning the accuracy of the reconstruction of high-intensity beam profiles.