Mass Attenuation Coefficient and Effective Atomic Number for Cu, Zn and Ag Alloys by Attenuation of Compton Scattered 662 keV Gamma Rays

Abstract

The mass attenuation coefficients (μ/ρ) and effective atomic numbers (Zeff) of Cu–Ag, Cu–Zn and Ag-Zn alloys were experimentally studied with Compton-scattered gamma photons from a 662 keV ¹³⁷Cs source. By changing the angle of scattering from 45° to 0°, we had scattered photon energies in the range of (479−662) keV. Spectra were accumulated as an attenuated spectra with a resolution exceeding 256 channels using the NaI (Tl) scintillation detector coupled to the multichannel analyser (8K). FLUKA simulation and maximum-likelihood expectation-maximization (MLEM) deconvolution were used for photopeak reconstruction and peak discrimination enhancement. Mass attenuation coefficients were determined both experimentally by the Beer–Lambert law, and theoretically through the mixture rule and reference attenuation values. Then, atomic and electronic cross-sections were calculated in order to estimate Zeff for each alloy composition. The measured attenuation coefficients exhibited a decreasing trend with increasing photon energy and were in good agreement with theoretical values. Results validate the utility of MLEM-complemented Compton-scattering measurements in describing photon attenuation in metallic alloy and suggest applicability to radiation-interaction, shielding and nondestructive-evaluation studies.