Comments on the ageing effect of gas-filled proportional counters

Abstract

A number of experiments are described which verify the suggestion that the changes occurring in the pulse-height distribution of proportional counters after 108-1010 counts can be explained by assuming the accumulation of a deposit on the anode wire. The counters were irradiated with monochromatic radiation of 2·1, 5·4 and 8·34 Å. Ar-10% CH4 and Ar-20% CO2 were used as counter gases; the changes were less pronounced with CO2 than with CH4. An X-ray fluorescence analysis of the deposit on the wires of some of the CH4 counters showed the presence of carbon. Some possible sources for the deposit material are discussed.