Proportional Counter Proton-Recoil Spectrometer with Gamma Discrimination

Abstract

A proton‐recoil methane proportional counter has been used as a neutron energy spectrometer in the presence of conversion electrons from background gamma rays. A difference in the rise time of the voltage profile for conversion‐electron and recoil‐proton events of the same total ionization was made the basis for an electronic gamma‐neutron discrimination technique. Use of the gamma rejection technique was equivalent to an effective reduction in gamma sensitivity of the detector by a factor of 450. Spectroscopic information on a broad incident neutron spectrum was extended from the region above 350 keV to that above 80 keV.