A comparative study of empirical formulas for gamma-ray dose build-up factor in iron and lead materials

To analyse the difference between different empirical formulas for calculating gamma-ray dose build-up factors, we compared the gamma-ray dose build-up factors calculated according to Taylor's formula and Berger's formula for iron and lead materials. The results show that the differences between the two formulas are related to energies of gamma-ray, shield thicknesses and types of shielding materials. When the energy of gamma-ray and thickness of shield are determined, the gamma-ray dose build-up factor calculated by Taylor's formula is higher than that by Berger's formula for iron material. For lead material, the gamma-ray dose build-up factor calculated by Taylor's formula is lower than that by Berger's formula. Generally speaking, the higher the gamma-ray energy and the thicker the shield material, the greater the difference between the gamma-ray dose build-up factors calculated according to the two empirical formulas.