Status of Angular Distribution Measurements of Photo-Neutron Yields from Cu, Sn, and Pb Targets Irradiated by 2 GeV Electrons

The study of differential photo-neutron yields by the irradiation of 2 GeV electrons has been carried out. In this extended study of previous measurements, which were done at the angle of 90° relative to incident electrons, the differential photo-neutron yield was obtained at two other angles of 48° and 140° to study its angular characteristics. The experimental setup was improved to reduce huge photon backgrounds in a linear accelerator tunnel. Photo-neutron spectra were measured using a pulsed beam time-of-flight method. The neutron energy range of reliably measuring was from 8 MeV to 250 MeV. The status of this measurement study and differential photo-neutron yields produced from thick Cu, Sn, and Pb targets were presented. These results show the angular characteristics obviously.