Short-Lived Radioisotope Tc 98 Synthesized by the Supernova Neutrino Process

The isotope Tc98 decays to Ru98 with a half-life of 4.2×106 yr and could have been present in the early Solar System. In this Letter, we report on the first calculations of the production of Tc98 by neutrino-induced reactions in core-collapse supernovae (the ν process). Our predicted Tc98 abundance at the time of solar system formation is not much lower than the current measured upper limit raising the possibility for its detection in the not too distant future. We show that, if the initial abundance were to be precisely measured, the Tc98 nuclear cosmochronometer could be used to evaluate a much more precise value of the duration time from the last core-collapse supernova to the formation of the solar system. Moreover, a unique and novel feature of the Tc98 ν-process nucleosynthesis is the large contribution (∼20%) from charged current reactions with electron antineutrinos. This means that Tc98 becomes a unique new ν-process probe of the temperature of the electron antineutrinos.