COHERENT AND INCOHERENT-SCATTERING OF 14.93, 17.44 AND 21.12 KEV PHOTONS FROM AL, CU, SR, CD, CE, PR, SM, PT, AU AND PB

Coherent and incoherent scattering cross sections for the elements Al, Cu, Sr, Cd, Pr, Ce, Sm, Pt, Au and Pb have been measured at 14.93, 17.44 and 21.12 KeV K-alpha X-ray energies. Measurements have been performed using an X-ray tube with a secondary exciter system as the excitation source instead of radioisotopes. Bremsstrahlung radiation from the X-ray tube has been used to excite nearly monoenergetic X-rays in secondary targets. In order to improve the efficiency of the detection system the excitation source detector and the target assembly were placed in a vacuum chamber and a pressure of 10(-2)mbar is maintained throughout the measurements. The coherently and incoherently scattered intensity by the sample into the detector has been detected at an angle of 90 degrees using low energy HP Ge and Si (Li) photon detectors. The present system considerably reduced the scattering and background effects and improved the monochromacy. Experimental scattering cross sections are compared with the normalised integrated cross section based on form factor and incoherent scattering approximations. The present experimental results do not strongly support any set of theoretical values. More accurate experimental results and extended exact calculations of atomic form factors at more closely spaced values of incident X-ray energies and scattering angles are clearly needed if more meaningful comparison between experiment and theory are to be possible.