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.