Parallel ionization multiplier : A gaseous detector dedicated to the tracking of minimum ionization particles

Abstract We report gain and discharge rate measurements with micropattern gaseous detectors using micromeshes. Some geometrical configurations of parallel ionization multiplier (PIM) and MICROMEGAS, operated with Ne+10% CO 2 gas mixture, are considered. Tests have been performed on the T9 proton–pion beam facility at CERN (PS). For MICROMEGAS configurations, the discharge rate, when greater than 3×10 −7 , is correlated to the thickness of the amplification gap. On the other side, for lower probabilities, the amplification gap thickness does not seem to be discriminatory, suggesting that some particularly interesting physic interactions are observed. With the PIM structure operated at a gain of 5000, the best configuration allows to achieve a rate of discharges lower than 10 −9 . Some elements are now understood to reduce this discharge rate with only two amplification stages, such as using ions with greater velocities or thinner amplification gap. R&D activities are under progress in order to complete this study.