Response matrix evaluations of a passive Bonner sphere system used for neutron spectrometry at pulsed, intense and complex mixed fields

In the present work, the general purpose radiation transport MCNPX code (version 2.5.0) was used to evaluate the neutron fluence response matrix of the passive Bonner sphere spectrometer recently developed in our laboratory. The calculations were performed for an extended neutron incidence energy range (from 10 −9 MeV to 1 GeV). Afterward, a sensitivity analysis of the main parameters affecting the neutron fluence response of each detector-sphere assembly has been undertaken and complementary MCNPX simulations of bare gold foils considering normal , parallel and isotropic neutron incidence directions are also presented. Finally, the simulated response matrix was experimentally validated with a 252 Cf standard radioactive source available in our facilities.