Attenuation Cross Sections for 860-Mev Protons

Abstract

Integral angular distributions of 860-Mev protons scattered by Be, C, Al, Cu, Sn, and Pb nuclei have been measured in a transmission experiment in which the half-angle subtended at the absorber by the detector was varied from 1.5° to 20°. A counter telescope technique employing plastic scintillation counters and a fast-coincidence circuit was used. From the cross sections measured with poor geometry it is possible to deduce the inelastic cross section for the heavy elements and, less unambiguously, also for the light elements. Agreement with 1.4-Bev neutron data from a concurrent experiment is good. Total cross sections could not be obtained for the heavy elements because of Coulomb effects, but for the light elements rough estimates could be made. The data are consistent with an interpretation in terms of the "optical" model of the nucleus with constant nuclear density. If the nucleon-nucleon cross section at this energy is taken to be 45 mb, these measurements yield a nuclear absorption constant $K$ of 0.56×${10}^{13}$ ${\mathrm{cm}}^{-1\mathrm{}}$ and a nuclear radius of the form $R=(1.25\mathrm{}\pm 0.02)A^{\frac{1}{3}}\times {10}^{-13\mathrm{}}$ cm.