MEASUREMENT OF K-SHELL PHOTOELECTRIC CROSS-SECTIONS USING A DIRECT METHOD

K-shell photoelectric cross sections are determined by the direct method at 661. 65 keV in Au at 30 degree and 40 degree and in Yb, Ta and U at 40 degree . A high resolution HPGe detector is used to detect both the X-ray and incoherently scattered gamma ray intensities simultaneously. The superiority of the direct method over the indirect method at higher energies is discussed. The results are showing a good agreement with the available theoretical and other experimental values. A close observation shows that the measured values are in a better agreement with the accurate and recently reported data of Scofield.