A SIMPLE METHOD TO MEASURE THE TOTAL COHERENT SCATTERING CROSS-SECTIONS OF ELEMENTS

A new method has been developed to determine total coherent scattering cross sections of elements for gamma rays. An important feature of th e method is that the elemental cross sections can be directly obtained from the total attenuation cross sections of their simple chemical co mpounds. The sample cross sections were measured in a narrow beam with a good geometry, set up using a well type NaI(TI) detector by positio ning the sample inside and outside the well. Using the cross sections corresponding to the two positions, the total coherent scattering cros s sections of the elements were determined. In this paper, we report t he cross sections so obtained for the elements Bi, Pb, W and Ba at a g amma ray energy of 661.6 keV. The results are compared with the non-re lativistic Hartree-Fock values of Hubbell et al. and the relativistic Hartree-Fock values of Hubbell and Overbo. Possible conclusions are dr awn from the present study.