Determination of effective resonance energies for the185Re(n,)186Re and187Re(n,)188Re reactions by cadmium ratio method

Abstract

The effective resonance energy (Ēr) values for the 185 Re(n, γ) 186 Re and 187 Re(n, γ) 188 Re reactions were measured by using the cadmium ratio method. 197 Au and 98 Mo isotopes were selected as dual monitors to determine the epithermal neutron spectrum shape factor in the irradiation sites of a 37 GBq 241 Am-Be neutron source. The analytical grade rhenium(VII) oxide samples were diluted with Al 2 O 3 powder to reduce neutron self-shielding effects, and they were put into 1-mm thick small cylindrical polytetrafluoroethylene (PTFE) boxes. Samples were irradiated in a 241 Am-Be neutron source. The activation produced in the irradiated samples was measured in close-counting geometry on the end cap of a Ge detector in order to obtain better counting statistics. The correction factors for gamma-ray self-absorption (Fs) , thermal neutron self-shielding (G th) , and epithermal neutron self-shielding (Gepi) effects were determined with suitable approaches. Consequently, the experimentalĒr-values were measured to be 3.49 ± 0.54 eV for 185 Re and 41.77 ± 6.79 eV for 187 Re target nuclide, respectively. Furthermore, theĒr-values were theoretically computed through up-to-date resonance data obtained from the ENDF/B VII library using two different approaches. Since there is no experimental data available in the literature for theĒr-values of these isotopes, the results were compared with the theoretical values in the literature.