A Distributed Beam Loss Monitor for the Australian Synchrotron

A distributed beam loss monitoring system, named the optical fibre Beam Loss Monitor, has been installed at the Australian Synchrotron. Relativistic charged particles produced in beam loss events generate photons via the Cherenkov mechanism in four silica fibres that run parallel to the beam pipe and cover the majority of the accelerator's length. These photons are then guided by the fibres to detectors located outside of the accelerator tunnel. By measuring the time of flight of these photons, the locations of beam losses can be reconstructed. Based on this method a calibration was produced, mapping the time of flight to a position along the accelerator. This calibration was applied to loss signals collected on the first pass of the beam through the accelerator and the locations of prominent losses were determined. Using this system it was possible to investigate the effect, on the location and intensity of losses, in response to changes in the lattice parameters on a shot-by-shot basis. This system is now used in routine operations and has resulted in a 40 % increase in the capture efficiency of the booster ring.