A MODEL OF BREAKDOWN IN PARALLEL-PLATE DETECTORS

Parallel-plate avalanche chambers (PPAC's) have many desirable propert ies, such as a fast, large area particle detector, However, the maximu m gain is limited by a form of violent breakdown that limits the usefu lness of this detector, despite its other evident qualities, The exact nature of this phenomenon is not yet sufficiently clear to sustain po ssible improvements, A previous experimental study is complemented in the present work by a quantitative model of the breakdown phenomenon i n PPAC's, based on the ''streamer theory.'' The model reproduces well the peculiar behavior of the external current observed in PPAC's and r esistive-plate chambers, Other breakdown properties measured in PPAC's are also well reproduced.