Determination of Neutron Scattering Cross Sections of ~9Be at Energies between 7.10 MeV and 9.97 MeV

摘要

Differential cross sections of elastic and inelastic neutron scattering on ~9Be were determined in the energy range from 7.10 MeV to 9.97 MeV at four incident energies. The data were derived by comparing the net time-of-flight spectra with calculated spectra using a realistic Monte Carlo simulation. The time-of-flight measurement was accompanied by extensive and careful calibrations. The beryllium cross sections have been normalized to hydrogen scattering. The disturbing breakup scattering fraction of the non-monoenergetic DD neutron source can be subtracted after having been calculated by a Monte Carlo simulation. The data for such a calculation are checked using an additional pure breakup neutron source based an the ~4He(d, np)~4He reaction. By proper subtraction of the breakup fractions, double-differential cross sections can be obtained for neutron emission energies down to 1.5 MeV. Partial inelastic cross sections could be determined for one low-lying level at excitation energy 2.43 MeV. Angle-integrated cross sections were derived by fitting Legendre polynomial expansions to the measured angular distributions using least-squares methods. The results of this work have been compared with those of other authors and with the ENDF/B-VI evaluation.