On spectrometric properties of transmission avalanche counters at moderate specific ionization

The purpose of this investigation is to determine the energy resolution of transmission avalanche counters at moderate specific ionization. Parallel-plate avalanche counters (PPAC) with an electrode spacing d from 0.1 to 0.4 cm have been used to register alpha particles emitted by 241Am, at n-heptane vapour pressures of p⩾5Torr. An analysis of complex spectral distributions was carried out for the detected particles to determine the effect of such a fine energy structure of the recorded spectrum upon the properties of the counters under investigation. The derived empirical curves of PPAC energy resolution have a plateau range that gets longer with the increase in p and d. The absolute values of the actual gas gain corresponding to the plateau ranges amounted from 4.6×10 to 2.91×104, while d=0.2-0.3 cm and p⩽30Torr. The obtained results have been discussed with respect to both veracity and conclusions involved with fluctuations of the charge generated in the interelectrode space of the detector.