Single Surface Barrier Detectors for Neutron Dosimetry and Associated Light-Ion Fluxes

Surface barrier detectors can measure the characteristics of neutron fields and related light-ion fluxes (LIF). Some of us have shown that a photodiode, with a suitably chosen radiator, can measure fluences of monoenergetic neutrons and have studied the shapes of a few continuous neutron spectra. Others have used silicon detectors to measure the energy of neutrons from reactions. We have attempted to perfect a simple, compact and inexpensive single surface barrier detection system to measure both the intensities and approximate spectral shape of continuous neutron and LIFs. We have measured such fluxes for three known collimated and uncollimated neutron beams with two geometrical configurations and with at least two different thicknesses of CH2 and CD2 radiators. All neutron flux data were obtained with a Au shield in front of the detector; this was removed for LIF measurements. The known shapes of the impinging neutron beams were used to calculate the expected recoil-particle spectra and such predictions have been compared with the experimental data. Also, data have been obtained with telescopes, with carbon foil and thin detector-grade silicon foil radiators. These data allow us to estimate contributions to the higher-energy portion of the recoil-particle spectra from reactions due to the carbon in the CH2 and CD2 radiators and due to the silicon in the detector. Corrections for rim effects in the detector and multiple scattering in the radiator are calculable.