LAYOUT OF THE BPM SYSTEM FOR P-LINAC AT FAIR AND THE DIGITAL METHODS FOR BEAM POSITION AND PHASE MONITORING

At the planned Proton LINAC at the FAIR facility four-fold button Beam Position Monitor (BPM) will be installed at 14 locations along the LINAC. Four of these BPMs will be mounted only about 40 mm upstream of the CH cavities. The coupling of the rf accelerating field to those BPMs was numerically investigated. The properties of a digital I/Q demodulation scheme were characterized by detailed lab-based tests. The performance was investigated by a 80 μA Ca 10+ beam at 1.4 MeV / u at GSI UNILAC for beam position and phase determination. The I/Q phase results were compared to a time-domain approach as well as successive FFT calculation. A significant deviation between the methods were observed and further investigations to understand the reason are ongoing.