Calculation of Attenuation Parameter for Ir-192 Gamma Source in Shielding Materials.

Purpose:Calculation of photon attenuation is necessary for the selection of shielding materials for an irradiation facility. Methods and Materials:In this work, a Monte Carlo simulation was utilized to assess the effectiveness of clay-polyethylene mixture and clay as the radiation shielding materials for high-energy gamma sources (Ir-192). Ordinary concrete was also studied as the benchmark. Results:The calculated linear attenuation values for ordinary concrete are within 0.44% of the standard XCOM value for 380 keV photon. In the case of a multienergy Ir-192 gamma source, the calculated linear attenuation coefficient (μ) for ordinary concrete is 15.5% and 7.25% higher than clay and fabricated clay-polyethylene, respectively. Meanwhile, the μ value for fabricated clay-polyethylene is 8.3% higher than that of clay. Conclusion:In conclusion, a 10 cm thickness of clay and clay-polyethylene mixture is sufficient to attenuate 87% and 89% of photons from Ir-192 source. The calculated linear attenuation coefficients for the three shielding materials are also consistently higher, about 7.5%, than that of the XCOM value for 380 keV photon.