Investigation of γ-ray attenuation coefficients, effective atomic number and electron density for ZnO/HDPE composite

Abstract

Bulk and nano ZnO/HDPE composite with different weight fractions (10, 20, 30 and 40%) of ZnO as a filler were prepared and studied for radiation shielding properties against γ-ray. The structural, morphological and functional properties of the composites were identified using x-ray diffraction (XRD), scanning electron microscope (SEM) and Fourier transform infrared specrtroscopy (FTIR). The results confirmed the formation of ZnO nanoparticles with crystallite size of 27 nm and revealed their good dispersion within the polymer matrix compared to bulk ZnO as well as interaction mechanism between the filler and the polymer matrix. The mass attenuation coefficient (μm) for the composite was measured experimentally using a well calibrated high purity germanium cylindrical detector (HPGe) at energies (59.54, 356.01, 661.66, 1173.33 and 1332.50 keV) for different radioactive point sources (241Am, 133Ba, 137Cs and 60Co). The obtained attenuation coefficients were used to determine the values of total molecular cross section σmol, the total atomic cross section σatm (cm2/atom), total electronic cross-section σel (cm2/electron) effective atomic number Zeff, and effective electron number Neff. Using NIST XCOM photon cross section database, the theoretical radiation parameters were calculated for bulk ZnO/HDPE composite and compared with the experimental results of both bulk and nano ZnO/HDPE composite. The obtained results revealed good agreement compared to theoretical values. μm, σmol, and σatm values decreased with incident photon energy and increased with weight percentage of both bulk and nano ZnO filler. However, these values were greater for nano ZnO/HDPE composite compared to bulk ZnO/HDPE composite with the same weight percentage. Whereas, σel, Zeff and Neff values decreased with weight percentage and revealed a plateau region which appeared with further increase in energy.