Determination of saturation depth in aluminium and lead for 662 keV gamma rays

摘要

Compton scattering process is a powerful tool for determining electron distribution in an atom, non-destructive testing of a sample and reactor shielding. There is a significant radiation dose arising from the gamma rays backscattered from the surface of the shielding material. Present experiment is performed to study the contribution of multiply scattered photons as a function of thickness of the scatterer in the backscattering geometry. For this purpose a 137{sup left}Cs radioactive source of strength 110 mCi is used to obtain 662 keV gamma rays. The incident gamma rays irradiates the samples of aluminium and lead of different thicknesses in the backscattered geometry. The backscattered photons are detected by a Na1 (T1) scintillation detector of dimensions 51 mm diameter and 51 mm thickness at a scattering angle of 120°. To extract the contribution of the multiply scattered photons from the measured spectrum, a singly scattered photon spectrum is reconstructed analytically. Saturation depth is determined from experimental data and it comes out to be 90 mm and 9 mm for aluminium and lead respectively.