We have performed the measurement of neutron emiSSIOn spectra from 238 U using a timeof-flight technique, and deduced the following data; (1) the prompt fission neutron spectra for 2 MeV incident neutrons at two emission angles of goo and 135o, (2) the double-differential neutron emission cross sections at the incident energies of 1.2, 2.0, 4.2, 6.1 and 14.1 MeV. The emission spectra and the cross sections for scattering process were also deduced by subtracting the fission neutrons from the experimental spectra. The experimental results were compared with other experiments and the evaluations of JENDL-3 and ENDF/B-IV. From the fission spectrum data ranging from 2 to 12 MeV, we have derived the best fit parameters for the Maxwellian and Watt type distribution functions. The experimental spectra are described with the Maxwellian spectrum with temperature of 1.24-1.26 MeV and are softer than both evaluations. The spectra and cross sections for inelastic-scattering showed substantial disagreement with the evaluations concerning the discrete levels between 0.5 and 1.2 MeV, and continuum neutrons due to evaporation and pre-equilibrium processes. The secondary neutron angular distributions at 14 MeV incident energy were reproduced fairly well with the systematics.
We performed measurements of neutron elastic scattering cross sections of carbon, silicon, iron, zirconium and lead at 75 MeV using a 7 Li(p,n) quasi-monoenergetic neutron source at TIARA of JAERI. Neutron spectra at 25 laboratory angles between 2.6° and 53.0° were measured by a time-of-flight method (TOF) using five liquid scintillation detectors. The data were corrected for the inelastic scattering neutrons and sample size effects. The experimental data were compared with the neutron cross section libraries (DLCI I 9/HIL086, LA 150) and systematics used in cascade/transport codes (HETC-KFA2, NMTC/JAERI). The DLC 119 data and sytematics show large discrepancy from the present data, while the LA 150 data are in fair agreement.
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