The gas proportional scintillation counter/microstrip gas chamber hybrid detector with argon filling

We present the results of a study of an argon gas proportional scintillation counter instrumented with a CsI-coated microstrip plate placed in the argon envelope. Although the measured light amplification gain and the photoelectron collection efficiency are 70% and 30–40% higher than those obtained in a similar xenon detector, the charge gain achieved in argon for the avalanches produced by the photoelectrons at the microstrip anodes is a factor of ten lower than in xenon. In both cases, these gains are limited by optical positive feedback. The energy resolution achieved for 5.9 keV X-rays was 14.8% compared to 12% in xenon.