Effective Atomic Number Determination of Rare Earth Oxides with Scattering Intensity Ratio

Effective atomic numbers ( ) of scientific samples (rare earth) were determined experimentally by scattering of 59.54？keV gamma photons from 5？Ci 241Am annular radioactive source. The scattered gamma photons were collected by using a high-resolution HPGe semiconductor detector placed at to the incident beam. This experiment was carried out on several elements in the atomic range for 59.54？keV incident photons. Photopeak efficiency and air and sample absorption corrections were performed on Rayleigh to Compton scattering intensity ratio; then the ratio was plotted as a function of atomic number and a fit curve was constituted. The effective atomic numbers of rare earth oxide samples were determined by this fit curve. Also, related parameters were determined by absorption technique with the same incident photon energy. Obtained values from this fit curve were compared to theoretical values and were found to closely agree with theoretical calculations. 1. Introduction Effective atomic number is an important parameter that should be determined for materials in composite, alloy, and mixture form. Reliable data on the effective atomic numbers were used in radiation biology, medical physics, radiation dosimetry, nuclear industry, and space research programs. Also, the effective atomic number is used for determining the X- and γ-ray absorption fraction of materials. There are a few techniques (particle induced X-ray emissions (PIXE), proton induced gamma ray emission (PIGE), fast neutron activation analysis (FNNA), induced coupled plasma (ICP), electrical impedance methods, XRF, chemical analysis, and atomic absorption spectroscopy) to define the effective atomic number of composite materials that was created by two or more constituents. One of these techniques is total photon interaction calculation by using transmission experiments. In addition to these techniques, intensity ratio of scattered photons, emerging from suitable sample-source and detector arrangement, was a significant experimental method to determine effective atomic number in a nondestructive way. The scattered intensity ratio method is regardless of density of the sample and depends on the mixture of composite material. The above-mentioned research techniques used in a present study are subapplication of the XRF technique. Rare earth oxides of lanthanids are widely used in scientific, industrial, commercial, and medical applications. For example, praseodymium oxide in solid solution with ceria or ceria-zirconia is used as oxidation catalysis; europium oxide is used in nuclear reactor as a