Experimental Setup for Measurements of High Energy Photo-neutron Spectra from Thick Targets

Photo-neutron spectra produced by 2.04 GeV electron incident on thick A1, Cu, Sn and Pb targets were measured by TOF method. An efficiency of used detector PILOT-U was calculated by SCINFUL and Cecil’s code. The efficiency was also measured for neutron energies at 14.9, 33, 66.0, 86.5, and 132.0 MeV to confirm the calculated results. However, there is a discrepancy between those two results. A Pb attenuator was placed at the middle point of the flight path to suppress γ-flash signals. The thickness of the attenuator was changed from 10 cm to 30 cm for each target, and the effects of the attenuator on the neutron spectra were calculated by a combination of small changed LAHET code and ENDF-HE/VI data. Obtained neutron spectra from each attenuator case were agreed with each other for neutron energy from 10 MeV to 300 MeV.