Measurement of neutron energy spectra behind shields for quasi-monoenergetic neutrons generated by 246-MeV and 389-MeV protons using a Bonner sphere spectrometer

Abstract

Neutron energy spectra behind concrete and iron shields were measured for quasi-monoenergetic neutrons above 200 MeV. Quasi-monoenergetic neutrons were produced by the 7 Li(p,xn) reaction with 246-MeV and 389-MeV protons. A Bonner sphere spectrometer was used to obtain the neutron energy spectra. Shielding materials are concrete blocks with thicknesses from 25 cm to 300 cm and iron blocks with thicknesses from 10 cm to 100 cm. The neutron energy spectra behind the concrete and iron shields were obtained by the unfolding method using the MAXED code. Ambient dose equivalents were obtained as a function of a shield thickness successfully. These experimental data will be useful to perform accurate shielding design, benchmark calculation codes and evaluate neutron cross section data.