Neutron and gamma albedo characteristics for two-layer aluminium-air scatterers

Different neutron and gamma albedo characteristics for two-layer aluminium-air reflectors have been studied by the Monte Carlo method applied to unidirectional sources. Thus calculated integral spectral and differential numerical albedo for different neutron energy groups as functions of the incidence angle THETA0 and the scattering angle THETA are presented. The strongest azimuthal variations of the albedo were found for neutrons at E>=2 MeV, they lessening with decreasing E. The calculated numerical gamma albedo as a function of the source energy (1-6 MeV) and THETA 0 are also presented. As THETA 0 increases, the gamma albedo increases as well as the ''hardness'' of the reflected spectrum. The pattern of the angular dependence of the numerical gamma albedo is reminiscent of that for neutrons