Absolute Neutron Spectrum Measurements in a Lithium Fluoride Integral Assembly for Fusion Reactor Data Assessment

A miniature NE-213 scintillation counter and hydrogen proportional counters have been used in conjunction with a calibrated 14-MeV deuterium-tritium neutron source to measure the neutron flux per source neutron per second at a number of positions in a 1.25-m-diam sphere of lithium fluoride. The experimental techniques used are discussed, and the resulting neutron spectra are compared with those from one-dimensional S_n calculations using the ENDF/B-IV data set, allowance being made both for neutron yield anisotropy and for the variation in source neutron energy with angle of emission.