On using CF2 as working gas for drift tubes

The results of studying the characteristics of the drift tubes with a cathode diameter 29 mm, filled with pure freon CF4, are presented. With the anode diameter of 100 μm and detection threshold of 2.0 μA, the detection efficiency for minimal ionizing particles is 93%. In the case of the anode diameter 40 μm at a distance between the particle track and the tube axis less than 10 mm the detection efficiency is not less than 99%. The amplitude spectra, space-time dependences are presented and the space resolution has been determined. The maximum electron drift time is 161 ± 3 ns, the coordinate resolution σx is equal to 0.5 mm. No deterioration of the tube performances was observed on passing 2 x 1011 minimal ionizing particles through 1 cm of the anode length. (orig.)