PHOTON-ATOM SCATTERING OF 13.95-KEV, 17.75-KEV, 26.36-KEV, AND 59.54-KEV PHOTONS BY CU, ZN, ZR, NB, MO, AG, CD, IN, SN, TA, AND W

Differential coherent scattering cross sections for 11 moderate-to hig h-atomic-number elements have been experimentally determined with O(10 %) error at the photon energies 13.95, 17.75, 26.36, and 59.54 keV, co rresponding to major photon-emission intensities of the radionuclide A m-241. The measurements were performed using a standard backscattering geometry setup to obtain scattering angles of 145 degrees, 154 degree s, and 165 degrees, with resulting photon momentum transfers in the ra nge 1.07 less than or equal to x less than or equal to 4.76 Angstrom(- 1). High-purity (better than 99%) foils of Cu, Zn, Zr, Nb, Mo, Ag, Cd, In, Sn, Ta, and W were used as targets. A hyperpure germanium detecto r completed the arrangement. Measurements for Mo and Zr using the 17.7 5-keV photon-energy emission of Am-241 were not possible due to the fa ct that for these targets at this photon energy, intense fluorescence overlapped significantly with the coherent scatter. At 26.36 keV the c oherent scatter from Cd was similarly dominated by fluorescence. Exper imental data have been compared with predictions from relativistic for m factors (RFFs), modified relativistic form factors (MRFFs), and coun terpart RFF and MRFF approximations with anomalous corrections using a ngle-independent scattering factors.