Study on the shielding materials for low-energy gamma sources

Abstract

Photon dosimetry is indispensable in designing an irradiation facilities shielding. Monte Carlo simulation was utilized to investigate the efficiency of relatively new developed clay and Gadolinum (Gd)-doped polymer as a radiation shielding material for low energy gamma sources (Am-241 and Co-57). The calculated linear attenuation coefficient () of Am-241 and Co-57 for clay is higher within 6.6 % and 0.9 % compared to ordinary concrete, respectively. The value for Gd-doped polymer is higher by a factor of 9 and 5 compared to clay for Am-241 and Co-57, respectively. A thickness of 2 cm and 5 cm from both clay and concrete were adequate to attenuate almost 90 % incident photons from Am-241 and Co-57, respectively. The same thickness of 2 cm by Gd-doped polymer could attenuate almost 95 % of Co-57 photons. 3 cm thickness of clay and concrete could shield the gamma source dose rate of Am-241 (1 MBq) down to 0.05 Sv/hr, while almost 10 cm needed for Co-57 source. Gd-doped polymer with thickness of 2 cm could shield almost 94 % the dose rate from Co-57 source. For higher energy gamma sources, clay and ordinary concrete need to be doped with a higher Z element to ensure safety of the radiation.