Speaker
Description
The Gupta-Meyer treatment of nuclei with long-lived isomers computes the effective internal equilibration rate by assuming that the higher-lying nuclear levels, through which the ground and isomeric states communicate, are in steady-statel [1]. The effective rate for transition between the ensemble of states associated with the ground state and the ensemble of states associated with the isomeric state then becomes a sum over probabilities of pathways between the ground and isomeric state. The treatment also permits the computation of nuclear partition functions for the ground-state and isomeric state ensembles. This allows the two ensembles to be included in the reaction network as separate species. This talk will present the Gupta-Meyer technique, discuss the nuclear physics data required for proper calculation of the reaction rates between the ensembles and between the ensembles and other network species, and illustrate some effects of isomers with network calculations of i-process and r-process nucleosynthesis. It will also present some open-source tools for computing relevant rates for nuclides with isomers and for incorporating those rates in a reaction network.
[1] Gupta, S. S. and Meyer, B. S. (2001) PRC, 64, 025805.
