Measurement of the neutron spectrum by the irradiation of a 2.04-GeV electron beam into thick targets

Inclusive neutron spectra produced by the irradiation of a 2.04-GeV electron beam into thick Al, Cu, Sn and Pb targets were measured by the TOF method. For such a high-energy region, it was the first experiment to measure the inclusive neutron spectra. A lead shield was placed at the middle point of the flight path to suppress any strong photon or electron background. The effects of the shield on the neutron spectra were calculated by the LAHET2.7 code with a small modification. The measured neutron energy in the experiments was from 10 to 200 MeV. The measured spectra were used for a benchmark test of our modified PICA95. It was found that the neutron spectra predicted by a combination of EGS4, our modified PICA95 and LAHET2.7 codes, tend to underestimate the measured ones.