Neutron Scattering Angular Distributions in ²³⁹Pu at 570 and 700 keV

Neutron elastic and inelastic scattering in ²³⁹Pu have been studied via the time-of-flight technique. Neutrons were generated by the ⁷Li(p, n)⁷Be reaction at the University of Massachusetts Lowell 5.5-MV Van de Graaff Accelerator Laboratory. Angular distributions were measured at 570 and 700 keV for two level groups, ground state plus first excited state, and second plus third excited state. The plutonium sample was disk-shaped with a mass of 28.7 g. The angle-integrated cross sections obtained for the two scattered neutron groups, one corresponding to the elastic plus 7.9 keV level and the other corresponding to the inelastic 57 keV plus 76 keV levels, were 5864 ± 264 mb and 570 ± 42 mb, respectively, for 570-keV incident neutrons and 5060 ± 308 mb and 518 ± 62 mb, respectively, for 700-keV incident neutrons. The results are compared with ENDF/B-VI and with the measurement of Haouat et al. at 700 keV.