Calculation of resonance self-shielding factors in a round disk using the enlarged Doppler Broadening Function

摘要

The activation technique allows much more precise measurements of neutron intensity, relative or absolute. This technique requires the knowledge of the Doppler Broadening Function to determine the resonance self-shielding factors in the epithermal range. In this technical note the influence of considering the enlarged Doppler Broadening Function proposed by Palma et al. in the calculation of the self-shielding factors in the epithermal range in round disks is evaluated. Although the enlarged Doppler Broadening Function version shows considerable deviations from the conventional Doppler Broadening Function when xi <= 0.06 it has been shown that the effect is not fully transmitted to the calculation of the self-shielding factors in the epithermal range of Th-232, Pu-240, and U-238 isotopes. Thus, it is possible to conclude that there is no measurable gain in using enlarged Doppler Broadening Function instead of conventional Doppler Broadening Function in the activation technique and the conventional version is recommended in this application. For applications involving higher temperatures and consequently lower values of parameter xi, there may be a gain depending on the degree of precision required in the calculations. (C) 2017 Elsevier Ltd. All rights reserved.