An argon gas proportional scintillation counter with UV avalanche photodiode scintillation readout

An uniform-field argon-filled gas proportional scintillation counter, using a large-area avalanche photodiode, is presented. The excitation and ioniza tion thresholds for argon were found to be approximately 0.7 and 3.7 V cm(- 1) torr(-1), respectively. An upper limit of 0.30 +/- 0.04 was measured for the argon Fano factor for 5.9-keV X-rays. An energy resolution of 12.5% fu ll-width-at-half-maximum was achieved for 5.9-keV X-rays. The ultraviolet l arge-area avalanche photodiode proved to be suitable for reading the scinti llation light of an argon-filled gas proportional scintillation counter, pr oviding a quantum efficiency of about 50 % at 128 run. Good photodiode perf ormance is already achieved for gains about 100.