LOW-MOMENTUM-TRANSFER INCOHERENT GAMMA-RAY SCATTERING BY MODERATE-ATOMIC-NUMBER TO HIGH-ATOMIC-NUMBER ELEMENTS

We focus on the question of accuracy of prediction in the application of nonrelativistic wave functions for deriving incoherent scattering functions for photons. The present investigation involves the measurement of incoherent scattering intensity using an annular-target arrangement for momentum-transfer values in the range 1.5 up to 7.5 angstrom-1. Extrapolation of measurements performed using a minimum of three target weights for each angle of scattering provides both a means for correction of target attenuation and a system for monitoring departures from systematic experimental procedures. Results of measurements, good to within a conservative experimental uncertainty of 10%, reveal no systematic trend in departure from agreement with tabulated incoherent-scattering-function predictions based upon nonrelativistic wave functions. We also compare measured total-atom, total-scatter (coherent plus incoherent) differential cross sections with the best available predictions.