Transmission of medium energy neutrons through concrete shields

Transmission measurements of medium energy neutrons through concrete shields are described. Neutrons which were produced by the bombardment of 75 MeV protons on a thick Cu target, were collimated to a 7.5cm diameter beam, and injected onto concrete shields of 20, 50 and 100cm thickness. Neutrons transmitted through the shields were measured by an NE-213 scintillator. The Monte Carlo simulation of the neutron transport was made using the MORSE code based on the DLC-87 Hilo multigroup cross sections. It was seen from the comparison between the calculated and measured fluence that the attenuation profile of the integrated fluence above 20 MeV, as well as the penetrated neutron spectra, were well reproduced by the DLC-87. The usefulness of the DLC-87 cross section data was verified for the concrete shield calculation. (author)