Production of ⁹⁷Tc in Core-Collapse Supernovae

Core-collapse supernovae are known to produce the short-lived radionuclide ⁹⁸Tc (half life of 4.2 Myr).  This production is enhanced by charged-current neutrino capture reaction ν_e + ⁹⁸Mo -> ⁹⁸Tc + e^- [1]. Such supernovae also produce ⁹⁷Tc (half life of 4.21 Myr), and we point out that this production can be also be enhanced by the reaction ν_e + ⁹⁸Mo -> ⁹⁷Tc + e^- + n.  We have computed cross sections for charged-current neutrino capture on ⁹⁸Tc and have estimated the branching ratio for neutron emission.  We apply these cross sections to a supernova nucleosynthesis model with the result that neutrino reactions on ⁹⁸Mo can increase production of ⁹⁷Tc by a factor of roughly four. This enhancement may have implications for the presence of live ⁹⁷Tc in the early Solar System.

[1] Hayakawa et al. (2018), PRL, 121, 102701