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MPINP:
Research group A. Pálffy – Division C. H. Keitel
Abstract:
In the process of slow neutron capture nucleosynthesis, one often has to take into
account that nuclei undergoing neutron capture and beta decay may not be only in
their ground states, but also in long-lived excited states, known as nuclear isomers.
Such isomers might not be thermally equilibrated with the nuclear ground states. In
this thesis, we theoretically investigate the efficiency of nuclear excitation by electron
capture (NEEC) to deplete such isomeric states in dense stellar plasmas under the sprocess
conditions. Due to the high charge states available in such plasmas, NEEC is
not always accompanied by its detailed-balance counterpart, the inverse process internal
conversion, and reaction rates can be considered separately. We investigate the cases
of 58m Co, 99mTc, 121mSn, 121mSb and 152mEu and compare the NEEC depletion rates
with relevant beta and gamma decay rates of the isomeric states. The results for 58mCo,
121mSb and 152mEu show that NEEC should be considered as relevant isomer depletion
channel in astrophysical plasmas.
