Neutron spectrum measurements from 1–16 MeV in beryllium assemblies with a central D–T neutron source

Beryllium has been proposed as both a neutron multiplier and as a plasma facing material for fusion reactors, and its neutron cross section up to 15 MeV or so is consequently of con- siderable importance, particularly for the (n, 2n) reaction. This paper reports on the results of a series of 14 MeV neutron transmission measurements using an NE213 scintillation spectro- meter with three di€erent thicknesses of beryllium shells. The experimental results are then compared with MCNP Monte Carlo calculations using the ENDF/B-VI data set. For all three shells the experimental results lie above those calculated for neutron energies between 8 and 11 MeV, whilst between 1 and 4 MeV they lie below. It is concluded that there are continuing uncertainties in the data