The Stilbene Scintillation Crystal as a Spectrometer for Continuous Fast-Neutron Spectra

A method is described for measuring neutron spectra in the energy range 1 to 10 Mev. The pulse-height spectrum of scintillations produced in a stilbene crystal by recoil protons originating in the crystal is analyzed to yield the incident neutron energy distribution. Insensitivity to gamma rays and electrons is achieved by utilizing differences in the pulse shapes of light pulses produced by electrons and protons. This spectrometer is useful for both group and continuous spectra and has been tested by measurement of the spectra from a Pu-Be neutron source and from the spontaneous fission of Cf252. Both measurements are consistent with previous data. The Pu-Be data definitely confirm a peak at 9.7 Mev that was suggested by previous data.