Experimental Evidence of an Equilibrium Property in Gamma-Ray Angular Spectra Penetrating Bulk Shields

Angular penetration gamma-ray spectra have been measured from a ⁶⁰Co source in point and plane geometries with both homogeneous and heterogeneous combinations of various thicknesses of iron and concrete slabs. The results are presented in the form of angular flux as a function of angle of deviation for particular secondary energies. The pseudoequilibrium behavior, with regard to penetration depth, of the angular spectra from certain source geometries was observed, and methods are suggested as to how this property could be incorporated in a gamma-ray transport code.