Measurement Of Secondary Neutron Double-differential Cross Section For ~9Be Induced By Neutrons

This experiment is conducted to measure time-of-flight spectra of secondary neutron in 8.19 MeV and 21.94MeV in the range of 20-150 degree for 9Be and 20-50 degree for polyethylene, by using equipments of China institute of atomic energy (CIAE), including HI-13 Tandem Accelerator, Reaction pulse neutron source D(d,n)3He and T(d,n)4 and multi detector fast neutron TOF spectrometer. The results were normalized to n-p scattering measurement.In the process of data analyses, a special Monte-Carlo code STREUER which was validated with the MCNP-4C code was employed to simulate the TOF spectra produced by the interaction between neutron and polyethylene. Factors such as the channel width of TAC, the differential nonlinearity, the true gamma peak position and the time response function of detector were taken into account as transforming the simulative spectra, the normalization factor and the broaden factor were acquired by comparing with the experimental net spectra which were applied to the analysis of 9Be experimental measurement. The TOF spectra of the interaction between neutron and 9Be were simulated by code STREUER, and differential cross section and double-differential cross section of two energy points were attained by comparing and iterating with experimental net spectra. To avoid the influence caused by neutron flux attenuation, multiple scattering and finite geometry, some necessary corrections were adopted when data analysis. Results from the measurement were compared and analyzed with evaluated data and other measurements.The theoretical calculation was performed with the code LUNF which was based on the Hauser-Feshbach and the exciton model. The DDX for 9Be induced by 21.94 MeV neutrons was calculated and compared with the experimental data. Proposals to improve the theoretical models were pointed out.