Shielding Experiments at High Energy Accelerators of Fermilab (II) —Spatial distribution measurement of reaction rate behind the shield and its application for Moyer model—

Abstract

JASMIN - Japanese and American Study of Muon Interaction and Neutron detection - a program for studies of shielding and irradiation effect around high energy accelerators has been started until 2007 using high energy proton accelerators located in Fermi National Accelerator Laboratory (FNAL) as a collaboration of JAPAN and FNAL. The series of the presentations entitled Shielding experiments at high energy accelerators of Fermilab describes the part of the results of this collaboration regarding transport of secondary particles, neutron and muon, from 120 GeV proton induced reactions through experimental data and simulation. In this study, the spatial distribution of reaction rate of activation samples which were placed on pbar anti proton target station were obtained. The measured data shows that the reaction rates on the outer surfaces of the iron and concrete shields increases toward the downstream of the target. The attenuation length for iron were obtained from depth distribution of reaction rates in iron shield. The obtained reaction rates were also fitted to Moyer's formula. The shape of angular distribution of fitted reaction rates agree with that of measured reaction rates for �� = 60 - 120 degrees.