Determination of effective resonance energies for the ${}^{185}Re(n,y){}^{186}Re$ and ${}^{187}Re(n,y){}^{188}Re$ reactions by cadmium ratio method

Özet

The effective resonance energy ( Er) values for the 185 Re(n,)186 Re and 187 Re(n,)188 Re reactions weremeasured by using the cadmium ratio method. 197 Au and 98 Mo isotopes were selected as dual monitors to determine theepithermal neutron spectrum shape factor in the irradiation sites of a 37 GBq 241 Am-Be neutron source. The analyticalgrade rhenium(VII) oxide samples were diluted with Al2 O3 powder to reduce neutron self-shielding effects, and they wereput into 1-mm thick small cylindrical polytetrafluoroethylene (PTFE) boxes. Samples were irradiated in a 241 Am-Beneutron source. The activation produced in the irradiated samples was measured in close-counting geometry on the endcap of a Ge detector in order to obtain better counting statistics. The correction factors for gamma-ray self-absorption(Fs) , thermal neutron self-shielding (Gth) , and epithermal neutron self-shielding (Gepi) effects were determined withsuitable approaches. Consequently, the experimental Er -values were measured to be 3.49 ± 0.54 eV for 185 Re and41.77 ± 6.79 eV for 187 Re target nuclide, respectively. Furthermore, the Er -values were theoretically computed throughup-to-date resonance data obtained from the ENDF/B VII library using two different approaches. Since there is noexperimental data available in the literature for the Er -values of these isotopes, the results were compared with thetheoretical values in the literature.