Which Gaseous Detector Is the Best at High Rates?

We report results from a systematic study of breakdown limits for various high rate gaseous detectors: PPAC’s, MGC’s, diamond-coated MSGC’s, MICROMEGAS, CAT. It was found that for all these detectors, the maximum achievable gain, before breakdown appears, drops dramatically with incident flux, and is sometimes inversely proportional to it. Further, in the presence of alpha particles, typical of the backgrounds in high-energy experiments, additional gain drops by 1-2 orders of magnitude were observed for some detectors. We discovered that breakdowns at high rates occur through what we have termed an “accumulative mechanism”, which does not seem to have been previously reported in the literature. Results of these studies may help to choose the optimum detector for given experimental conditions