X-Ray attenuation coefficients at different energies and the validity of the mixture rule for compounds around the absorption edge

The total mass attenuation coefficients for the elements Co, Mn and Co2O3, compounds CoCl2.6H2O, CoSO4, CoSO4.7H2O, MnCO3, KMnO4, MnCl2.2H2O, and MnCl2.4H2O were measured at different energies between 4.508 and 11.210 keV using a secondary excitation method. Ti, Co, Ni, Cu, Zn, As, Se were chosen as secondary exciter. Gamma rays (59.5 keV) emitted from an 241Am annular source were used to excite a secondary exciter and Kα (K–L3, L2) lines emitted of a secondary exciter were counted by a Si(Li) detector with a resolution of 160 eV at 5.9 keV. It was observed that the mixture rule method is not suitable for determination of the mass attenuation coefficients of compounds, especially at energy that is near the absorption edge. Obtained values were compared with theoretical values.