IEEE Nuclear Science Symposium, California, United States Of America, 4 - 10 November 2001, pp.525-529
We demonstrated experimentally that the main breakdown-triggering mechanism in most gaseous detectors, including micropattern gaseous detectors, is sporadic electron jets from the cathode surfaces. Each jet may, depending on conditions, contain randomly between a few up to 10(5) primary electrons being emitted in a time interval of 0.1 mus up to the range of ms. After the emission these primary electrons experience a full gas multiplication in the detector and create spurious pulses. The rate of these jets increases with applied voltage and very sharply at voltages close to the breakdown limit. We found that these jets are responsible for the breakdown-triggering at any counting rates used in our measurements, from 10(-2) Hz/mm(2) up to 10(8) Hz/mm(2).