Neutron scattering studies and optical model calculations in the 20 MeV region

Differential cross sections for elastic scattering of 21.6 MeV neutrons have been measured for 13 elements from Mg to Bi with an energy resolution of 0.5 MeV. The measured cross sections cover the angular range from 100 to 160O. The data have been analysed in terms of a conventional spherical optical model potential with and without a volume absorption term. Furthermore parametrizations of geometry and potential depths for cross section calculations are presented. Volume integrals for the real and imaginary potential parts have been calculated with the best fit parameters. The values of the integrals have been compared with results obtained from microscopic calculations according to Jeukenne, Lejeune, and Mahaux. The microscopic volume integrals agree well with those derived from the phenomenological potential