Radiation protective characteristics of some selected tungstates

The mass attenuation coefficients (μ/ρ) of calcium tungstate, ammonium tungsten oxide, bismuth tungsten oxide, lithium tungstate, cadmium tungstate, magnesium tungstate, strontium tungsten oxide and sodium dodecatungstophosphate hydrate were measured at 14 photon energies in the energy range of 81–1333 keV using 22Na, 54Mn, 57Co, 60Co, 133Ba and 137Cs radioactive sources. The measured μ/ρ values were compared with those obtained from WinXCOM program and the differences between the experimental and theoretical values were very small. The bismuth tungsten oxide has the highest μ/ρ among the present samples in the studied energy region. From the μ/ρ values, we calculated the half value layer, tenth value layer and mean free path, and the results showed that ammonium tungsten oxide (which has the lowest density) and bismuth tungsten oxide (which has the highest density) possess the highest and lowest values of these three parameters, respectively. Additionally, from the incident and transmitted photon intensities, we calculated the radiation protection efficiency (RPE). The bismuth tungsten oxide was found to have RPE 98.53 % at 81 keV, which has the maximum value among the present samples and this suggested that bismuth tungsten oxide is the best to be chosen as the γ radiation shielding material candidate among the selected samples.