BEAM PHASE DETECTORS FOR SPALLATION NEUTRON SOURCE LINAC

An ability to measure the beam phase accurately – within a fraction of a degree – is a requirement to the Spallation Neutron Source (SNS) linac diagnostics. Electromagnetic simulations and measurements have demonstrated a strong dependence of the measured beam phase on the transverse beam position inside a probe, when signals are picked up from individual electrodes. Two candidates for the beam phase detectors for the SNS linac – capacitive probes and beam positions monitors, either with signals from individual electrodes or with summed signals – are studied and compared using MAFIA simulations with an ultra-relativistic beam.