Measurement of Intermediate Energy Gamma-Ray Cross Sections

Abstract

Gamma-ray cross sections for 30 well-distributed energies from 121 keV to 10.827 MeV in 9 target elements ranging from carbon to uranium have been measured with an accuracy of better than 1%. Deviations from recently quoted theoretical cross sections were observed in the energy region from 6–11 MeV, particularly for high-Z target materials. The approximately Z2 dependent deviations are certainly associated with the elastic pair-production process, the present opinion being that they arise from an overestimation of the effects of atomic–electron screening on the pair cross section in the intermediate energy region.