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Turkish Journal of Physics

DOI

10.3906/fiz-1808-19

Abstract

The effective resonance energy ($\bar{E}_{r})$ values for the $^{185}$Re(n,$\gamma )^{186}$Re and $^{187}$Re(n,$\gamma )^{188}$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 ($F_{s})$, thermal neutron self-shielding ($G_{th})$, and epithermal neutron self-shielding ($G_{epi})$ effects were determined with suitable approaches. Consequently, the experimental $\bar{E}_{r}$-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, the $\bar{E}_{r}$-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 the $\bar{E}_{r}$-values of these isotopes, the results were compared with the theoretical values in the literature.

Keywords

Effective resonance energy, neutron activation, cadmium ratio, epithermal spectrum shape factor, rhenium

First Page

147

Last Page

155

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