Selected problems in aging effects with gas proportional counters

Influence of aging on energy resolution, length of energy resolution plateau, counting characteristic and self-induced space charge effect has been measured. We report results of aging studies performed by irradiating brass sealed proportional wire counters, filled with Ar/CO2 (90/10), Ar/CO2/N2/iso-pentane, (70/10/10/10) mixtures. The counters had different anode radii (15, 25 and 50 μm, respectively). 90Sr and 109Cd were used as radiation sources. Our experience shows that the aging rate depends not only on the total collected charge but also on the radius of the anode wire and on the type of radiation source.