Evaluation of response matrix of a multisphere neutron spectrometer with water moderator

Abstract

Neutron energy responses of water sphere spectrometers (WSS) to 30 MeV have been calculated by means of Monte Carlo calculations, using the computer code MCNP4C with ENDF/ B-VI.0 neutron cross-section. The calculations have been performed for 3 He detector (typical SP9) placed inside 2, 3, 5, 8, 12 and 18-inch diameter moderating spheres composed of water in aluminum shell. These simulations included a detailed description of the geometry of the system. The newly calculated responses have been compared to polyethylene sphere responses.