Investigation of some nuclear engineering materials in terms of gamma ray buildup factors at experimental energies used in nuclear physics experiments

ABSTRACT

In shielding studies, the gamma ray buildup factor is referred to an attenuation correction when the narrow beam transmission geometry conditions are not met. This is the case if there is a beam divergence and a considerably thick material is used as shield. In the present work, a linear logarithmic interpolation based on five parameter geometric progression (G-P) fitting method was used to calculate energy absorption (EABF) and exposure buildup factors (EBF) at discrete energies for some standard nuclear engineering materials (SNEM) such as concrete, Pb glass, brass, bronze and stainless steel, and for some recently developed shielding alloys and glasses. Calculations were made at different penetration depths (1–20?mfp) using photons emitted from the standard radioactive sources such as ¹³³Ba (0.356 MeV), ¹³⁷Cs (0.662 MeV), ⁶⁰Co (1.173, 1.332 MeV) and ²²Na (0.511, 1.275 MeV). Results have been compared with MCNP6.1 Monte Carlo simulation code wherever possible and a reasonable agreement (Relative difference around 10% up to 10?mfp except for Pb glass) has been achieved. Results also showed that the gamma ray buildup correction is necessarily required since buildup factors are greater than unity even at lowest penetration depth, i.e. 1?mfp. The reported data on EABF and EBF for the energy values of radioactive sources may be of practical use in shielding calculations and estimations.