Progress in CsI wire chamber imaging photomultipliers and single electron counters

Electrons photoproduced by UV photons on a CsI photocathode or deposited by ionizing particles and ultrasoft X-rays in low-pressure gas media can be efficiently detected in low-pressure multistep avalanche electron multipliers. A solid photocathode avalanche chamber (SPAC) imaging photomultiplier was coupled to a Xe-filled gas scintillation detector. Its performance when exposed to 60-keV X-rays is presented, and the stability of the CsI photocathode is discussed in detail. The latest experimental results from primary ionization cluster counting of charged particles and ultrasoft X-rays are presented. UV-laser-induced ionization and Monte Carlo simulations are used to study the processes involved.<
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