Spatial distribution measurement of neutrons produced by 120-GeV proton beam in concrete shield

The shielding experiment was performed at the anti-proton (pbar) production target station in Fermi National Accelerator Laboratory to obtain benchmark data for various transport calculation codes. At the pbar target station, an antiproton production target, consisted of Inconel and copper disks, were irradiated by 120 GeV proton beam. The beam intensity was 2.3 x 10¹² proton per second. The iron and concrete shields were placed on the upper side of the target. The thickness of iron and concrete shields were 188 and 122 cm, respectively. Aluminum, bismuth, and indium samples were placed in the concrete shields to measure the neutron energy spectra in the concrete shields. After irradiation, induced activities in samples were measured by using HPGe detector. The reaction rate spatial distributions of ²⁷Al (n, α) ²⁴Na, ²⁰⁹Bi (n, xn) ^{203,204,205,206}Bi, and ¹¹⁵In (n, n') ^115mIn reactions were measured in the concrete shields. The neutron energy spectra in the concrete shields were also obtained by unfolding the measured reaction rates with the aid of neutron induced reaction cross sections. (author)