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In the present paper, a universal analytical dependence of effective atomic number on the composition of matter and radiation energy is proposed. This enables one to consider the case of a strong difference in the elemental composition with respect to their atomic numbers over a wide energy range. The contribution of photoelectric absorption and incoherent and coherent scattering during the interaction between radiation and matter is considered. For energy values over 40 keV, the contribution of coherent scattering does not exceed approximately 10% that can be neglected at a further consideration. The effective atomic numbers calculated on the basis of the proposed relationships are compared to the results of calculations based on other methods considered by different authors on the basis of experimental and tabulated data on mass and atomic attenuation coefficients. The examination is carried out for both single-element (e.g., 6 C, 14 Si, 28 Cu, 56 Ba, and 82 Pb) and multi-element materials. Calculations are performed for W 1−x Cu x alloys (x = 0.35; x = 0.4), PbO, ther moluminescent dosimetry compounds ( 56 Ba, 48 Cd, 41 Sr, 20 Ca, 12 Mg, and 11 Na), and SO 4 in a wide energy range. A case with radiation energy between the K- and L 1 -absorption edges is considered for 82 Pb, 74 W, 56 Ba, 48 Cd, and 38 Sr. This enables to substantially simplify the calculation of the atomic number and will be useful in technical and scientific fields related to the interaction between X-ray/gamma radiation and matter. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this work was to develop a method to correct the absorbed radiation (the mass attenuation coefficient curve) in low energy (E <30keV) applied to a biological matrix based on the Rayleigh to Compton scattering ratio and the effective atomic number. For calibration, scattering measurements were performed on standard samples of radiation produced by a gamma-ray source of 241Am (59.54keV) also applied to certified biological samples of milk powder, hay powder and bovine liver (NIST 1557B). In addition, six methods of effective atomic number determination were used as described in literature to determinate the Rayleigh to Compton scattering ratio (R/C), in order to calculate the mass attenuation coefficient. The results obtained by the proposed method were compared with those obtained using the transmission method. The experimental results were in good agreement with transmission values suggesting that the method to correct radiation absorption presented in this paper is adequate for biological samples. [Copyright &y& Elsevier]