Investigation of the aging of gas-discharge detectors of particles with the use of nuclear reaction analysis

Abstract

This paper reports on the results of an investigation into the aging of drift tubes with anodes fabricated from gold-plated tungsten wires under continuous irradiation with a 90Sr beta source. The accumulated charge is as high as 9 C cm−1. The process of aging is studied in a gaseous mixture containing Ar, CO2, and CF4. It is revealed that the aging brings about a severe damage of the gold coating on a tungsten wire and an increase in the diameter of the wire in the irradiated zone from 35 to 42 μm. The observed swelling of the anode wire under forces applied from the inside is apparently a new mechanism of aging of anode wires. The swelling effect is assumed to be caused by the oxidation of the tungsten wire. It is demonstrated using the nuclear reaction analysis that the deposits containing tungsten, oxygen, carbon, and fluorine are distributed along the anode wire in the direction of the gas flow. The oxygen and fluorine distributions over the depth and along the length of the anode wire are determined.