Abstrakt
Partial gamma-ray production cross sections and the total radiative thermal-neutron capture cross section for the Re-185(n,gamma) Re-186 reaction were measured using the Prompt Gamma Activation Analysis facility at the Budapest Research Reactor with an enriched Re-185 target. The Re-186 cross sections were standardized using well-known Cl-35(n,gamma) Cl-36 cross sections from irradiation of a stoichiometric (ReCl3)-Re-nat target.
The resulting cross sections for transitions feeding the Re-186 ground state from low-lying levels below a cutoff energy of E-c = 746 keV were combined with a modeled probability of ground-state feeding from levels above E-c to arrive at a total cross section of sigma(0) = 111(6) b for radiative thermal-neutron capture on Re-185. A comparison of modeled discrete-level populations with measured transition intensities led to proposed revisions for seven tentative spin-parity assignments in the adopted level scheme for Re-186.
Additionally, 102 primary gamma rays were measured, including 50 previously unknown. A neutron-separation energy of S-n = 6179.59(5) keV was determined from a global least-squares fit of the measured gamma-ray energies to the known Re-186 decay scheme.
The total capture cross section and separation energy results are comparable to earlier measurements of these values.