Efficiency calibration of a cylindrical BC418 neutron detector at neutron energies between 135 and 800 MeV

The neutron detection efficiency of a cylindrical (5.08 cm diameter by 5.08 cm long) BC418 detector has been measured for neutrons at 780 MeV, using the time-of-flight technique to identify the transition to the ground and first excited states in the 7Li(p, n01)7Be reaction of 0deg. For energies between 135 and 800 MeV, and energy-dependent efficiency was also derived using published values of the zero-degree differential cross section for the Pb(p, n) reaction. Differences between the two approaches point to inconsistencies between the 7Li(p, n) and Pb(p, n) cross-section data. A comparison with predictions from a standard Monte Carlo code is given. For reference, also given are the attenuation length for 800 MeV neutrons in heavy concrete shielding and the total cross section in iron for neutrons from 110-725 MeV. (orig.)