Nuclear Cross Sections for 765 Mev Neutrons

Abstract

Total cross sections have been measured for the elements H, D, Li, C, O, Al, Cu, Sb and Pb and absorption cross sections for C, Al, Cu and Pb for neutrons of an effective energy of 765 ± 30 Mev. The neutrons were detected by observing the Cerenkov light from charged secondaries produced in a cylinder of Perspex. Large corrections must be applied to the measured absorption cross sections and these are strongly dependent upon the differential cross section assumed. The results are compared with an optical model with a potential distribution indicated by electron scattering measurements, and with an imaginary central potential and a real spin-orbit potential. The results can be adequately represented by assuming that at this energy the imaginary potential is given by the free nucleon-nucleon total cross sections and that the nuclear potential size and shape agree with the charge density size and shape. The spin-orbit coupling parameter required to fit the results is somewhat less than that found at lower energies.