Measurement of proton inelastic cross sections between 77 MeV and 133 MeV

Abstract

The proton inelastic cross sections of carbon, aluminium, copper, silver and lead have been measured in the energy range from 77 to 133 MeV using the external beam of the Harvard cyclotron. The measurements are made with a specially designed range telescope located in the external beam of the cyclotron. The cross sections are nearly constant in the energy range covered and average 0.225±0.005b for carbon, 0.423±0.009b for aluminium, 0.763±0.021b for copper, 1.060±0.025b for silver and 1.743±0.040b for lead. The lead and to some extent the silver inelastic cross sections seem to be decreasing with increasing energy within the 3% experimental error. The proton inelastic cross sections of the heavier elements, when corrected for the Coulomb repulsion of the nucleus, are significantly higher than the neutron inelastic cross sections. Optical model calculations can be interpreted as indicating a difference in the spatial distribution of protons and neutrons in these nuclei.