LAUSR

An analytical method for the a priori calculation of the thermal neutron die-way time was developed in order to optimize the detection of prompt and delayed gamma rays induced in the neutron activation of large samples irradiated in the facility MEDINA. The method was tested against experimental data collected in measurements of large homogeneous and heterogeneous samples using two different ways of calculating the neutron buckling value. The overall results are very satisfactory considering the simplifications performed to derive an analytical representation of the thermal neutron die-away time; the relative deviations for the experimental values are about 20%. However, when an effective buckling value is used the analytical die-away times show deviations not higher the 4% highlighting how the neutron buckling is the main source of error.