Thermal Equilibration of 176-Lu via K-Mixing

Abstract

In astrophysical environments, the long-lived (\T_1/2 = 37.6 Gy) ground state of 176-Lu can communicate with a short-lived (T_1/2 = 3.664 h) isomeric level through thermal excitations. Thus, the lifetime of 176-Lu in an astrophysical environment can be quite different than in the laboratory. We examine the possibility that the rate of equilibration can be enhanced via K-mixing of two levels near E_x = 725 keV and estimate the relevant gamma-decay rates. We use this result to illustrate the effect of K-mixing on the effective stellar half-life. We also present a network calculation that includes the equilibrating transitions allowed by K-mixing. Even a small amount of K-mixing will ensure that 176-Lu reaches at least a quasi-equilibrium during an s-process triggered by the 22-Ne neutron source.

9 pages, 6 figures

References in corpus (3)

• Nuclear Ground-State Masses and Deformations
• Survival of Nature's Rarest Isotope 180Ta under Stellar Conditions
• Properties of the 5- state at 839 keV in 176Lu and the s-process branching at A = 176

Cited by in corpus (4)

• The Branchings of the Main s-process: Their Sensitivity to alpha-induced Reactions on 13C and 22Ne and to the Uncertainties of the Nuclear Network
• Opportunities to constrain astrophysical reaction rates for the s-process through determination of the ground state cross sections
• Modification of nuclear transitions in stellar plasma by electronic processes: K-isomers in 176Lu and 180Ta under s-process conditions
• Nucleosynthesis of ${}^{92}$Nb and the relevance of the low-lying isomer at 135.5 keV