Design of 3He-Filled Fast Proportional Counters

Abstract
Electron drift velocity measurements have been made on helium, helium‐CO2, and helium‐CH4 mixtures in order to determine the optimum design parameters for 3He‐filled proportional counters. It is shown that small (<1‐in.‐diam) counters with neutron detecting efficiencies of greater than 1% at 1 keV and with jitter times of less than 1 μsec are practical. Calculated and measured jitter times for several counters are compared.