Neutron response functions and detection efficiency of a spherical proton recoil proportional counter

The neutron response function and detection efficiency of a spherical proton recoil proportional counter (SP) play key roles in precise measurement of neutron spectra of the interior materials. In this paper, the response functions and detection efficiency of three SPs developed at CAEP are simulated by Geant4. The simulated spectra are compared with pulse-height spectra measured at 0.165, 0.575, 1.4, and 14.1 MeV of incident neutrons. And the calculated detector efficiencies agree within 5% with the data obtained by neutron activation.