TOTAL CROSS SECTION MEASUREMENTS FOR HIGH ENERGY NEUTRONS UP TO 75 MeV AND TRANSMISSION EXPERIMENT FOR THE NEUTRONS THROUGH CONCRETE SHIELD
Department of Nuclear Engineering, Kyoto University
Yoshida-honmachi, Sakyo-ku, Kyoto 606, Japan
Institute of Nuclear Study, University of Tokyo
Midori-cho 3-2-1, Tanashi, Tokyo 188, Japan
Research Center for Nuclear Physics, Osaka University
Mihogaoka 10-1, Ibaraki, Osaka 567, Japan
Shimizu Construction Co. Ltd.
Etchujima 3-4-17, Koto-ku, Tokyo 135, Japan
This paper reports measurements of high energy (i.e., En ≤ 75 MeV) neutron spectra transmitted through concrete shields. A collimated beam of neutrons induced by 75-MeV protons in a thick Cu target was utilized in the measurements. The beam was injected to concrete shields of 40 cm by 40 cm in cross section and 20, 50 and 100 cm in thickness and neutrons transmitted through the shields were detected by an NE-213 scintillator.
Monte Carlo calculations by MORSE were carried out with the DLC-87 Hilo multigroup cross sections. It was found in the comparison between the measured and calculated spectra that the calculation with the above data gave overestimation to the measured data by a factor of two to three, whereas the shape of the spectrum was reproduced well.
Total cross sections of C, O, Si, Fe, Mo and Pb were measured in the energy range 25-70 MeV by the same neutron beam. The obtained data agreed well with other measured data. Slight disagreement was observed between the DLC-87 data and the measured data.
KEYWORDS: high energy neutron, transmission, concrete, benchmark test, accelerator shielding