Calculation of the thermal neutron flux perturbation factor for foil detectors in various media using the code PERTURB.D

The code PERTURB.D computes the thermal neutron flux perturbation factor, K, due to circular foils located in an isotropic neutron field. The calculation is based on the expression K = G.E.F, where G denotes the neutron self-shielding in the foil, E the edge correction factor and F the flux depression in the diffusing medium surrounding the foil. By comparison with published experimental results is was found that, for 66% (85%) of the sample cases, calculated K-values agree to better than 1% (2%) with the experimental ones. As an application of the code PERTURB.D, tables of K-values for different materials, including Mn, Co, In and Au, for diameters in the range 0.5 to 2 cm, and various practical thicknesses, both in water and graphite, are calculated and presented. (Auth.)