Simple expression of doses for X-rays below 1 MeV grazing incident on shields of concrete and iron backed by lead

Abstract

Doses for broad x-rays obliquely incident on slabs of concrete and iron backed by lead were calculated using photon/electron transport Monte Carlo codes. The results showed that the dose transmission in concrete with a thickness t can be expressed as D = D0e-μ′t at cos 0 = 0.01 and 0.1 between 0.2 and 1 MeV where 0 is the incident angle, D0 is the assumed source strength at the scattering point, and ft is almost equal to the attenuation coefficient for the nearly vertically scattered x-rays. The values of D0, which were dependent on θ, were tabulated for the two incident angles. For iron backed by lead between 0.08 and 1 MeV when θ was 88°, the attenuation slope gradually changed and converged to the rate corresponding to the energies of the nearly vertically scattered x-rays. The same experiment was also performed for a stainless steel pipe wrapped with lead foils of 0-2 mm thickness and white narrow x-rays with a peak energy of 0.09 MeV incident at 85°. The results reproduced the doses predicted by the Monte Carlo calculations at the maximum point.