PHOTON-ATOM SCATTERING OF 26.4 AND 59.5 KEV GAMMA-RAYS IN MO, NB AND ZR

Differential coherent scattering cross-sections have been experimental ly determined with 0 (10%) error for the photon energies 26.4 and 59.5 keV, using an annular 100 mCi Am-241 source. The source is housed in a stainless steel holder fabricated to contain heavy tungsten alloy sh ielding and capped with a beryllium window. The measurements were perf ormed using a standard back-scattering geometry set up to obtain scatt ering angles of 145 degrees and 165 degrees. Mo, Nb and Zr (Aldrich Ch emical Company, Inc.) foils of better than 99.9% purity were used as t argets in conjunction with a Hyper-pure Germanium detector. Measuremen ts using another prominent line at 17.8 keV are not presented due to t he fact that the intense fluorescence X-ray peaks overlap significantl y with the coherent scatter peaks from the Mo and Zr targets and the i ncoherent peak due to the Nb target. Experimental data have been compa red with theoretical predictions.