Increasing the background noise discrimination coefficient in proportional counter at the admixture of acetone vapors to the working gas

The results of the measurements of the background event discrimination coefficient on the pulse shape (Kd) are presented at fillings the proportional counters by the mixture Xe + GeH4 used for Ge-71 decay detection and the same mixture with a small acetone addition. It has been shown that the increasing Kd in the several times for the mixture Xe + GeH4 can be obtained by rising the concentration GeH4 (up to ≅70%) or adding (≅10 torr) acetone vapors (at the concentration GeH4 of 10 - 20%). The optimal magnitude of the time shaping constant is defined. 7 refs., 6 figs