Angular anisotropy of neutron inelastic scattering on Se nuclei and a role of direct mechanism of the reaction at Esub(n) approximately 1 MeV

The results of measurement of differential cross sections of elastic and inelastic scattering (ES and IS) of neutrons on sup(76, 78, 80, 82)Se nuclei at the neutron energy exceeding the threshold of excitation of the first levels 2+ by 525 keV for each nuclide. For measurements the time-of-flight neutron spectrometer has been used. The targets represent metallic selenium samples of 50-100 g weight enriched by sup(76, 78, 80, 82)Se isotopes up to 92-99%. For obtaining absolute values of scattering cross sections a normalization over cross section of np-scattering known with 1% error has been performed. Full error of cross sec-- tions measurement constitutes +-8% for IS and 7-9% for ES. From the angular distributions obtained ES and IS integral cross sections as well as total neutron scattering cross sections are derived. With the purpose of phenomenological description of experimental data calculations within the framework of the optical model with coupled channels are performed. Experimental and calculation cross sections are given in the table. It follows from the angular dependence (AD) of differential cross sections that the substantial contribution into IS is given by the p-wave outlet channel. The highest AD anisotropy is pointed out for 76Se and 82Se. The observed in the experiment character of cross sections angular dependence (AD) and the phenomenological analysis results confirm the previous conclusions on substantial role of the direct reaction mechanism in IS neutrons with Esub(n) approximately 1 MeV on Se nuclei and possibilities of considerable correlation of partial neutron widths of p-resonances