STUDIES OF RADIATION AGING OF THE STRAW PROPORTIONAL TUBES WITH XE-CO2-CF4 GAS-MIXTURE

We have investigated the radiation aging caused by 20 Kev X-rays of th e straw proportional tubes, which are supposed to be used in a transit ion radiation and tracking detector (TRT) in the ATLAS experiment at t he LHC. The main result of these investigations is that no observable drop in gas gain has been found up to the doses 5 C/cm. Still it has b een found that at certain experimental conditions the gas gain of a st raw transient, and dm value of gas gain returnes slowly to its initial value after the X-ray irradiation is switched off. The value of the g as gain decrease depends strongly on the dose rate and on the gas how rate. The results show that the observed transient aging of the straw proportional tubes will be quite negligible at the experimental condit ions expected for TRT at the LHC.