MACHINE-MODE AWARE BEAM LOSS MONITORING*

Beam-loss level monitoring is a powerful diagnostic tool concerning accelerator health. Particles leave the vacuum pipe for various reasons, such as intrabeam scat-tering (Touschek effect), residual gas molecules, closed orbit distortions or mechanical obstacles (aperture restric-tions, installation errors). These can be identified by ap-propriate measurements. The steady-state beam loss level varies throughout the machine and has to be measured and documented for further reference. Besides general radia-tion safety purposes, changes (especially increases) occur-ring after machine upgrades are of special interest. When simple monitoring of average beam loss fluctuations is insufficient, problem diagnostics should be further en-hanced by correlating beam loss monitor (BLM) detector readout with events in the machine. For best flexibility, pulses should only be counted at certain conditions and during well defined time slots synchronized with the cur-rent machine operation cycle. In cooperation with Cosy-lab, such an advanced BLM acquisition system was de-veloped for the Electron Stretcher Accelerator ELSA (University of Bonn, Germany), allowing various opti-mized acquisition modes