Recent research activities of division of nuclear physics.

I review the recent development of research groups of the Division of Nuclear Physics (DNP) in the Korean Physical Society (KPS) during the 2000s for commemorating the 50 year history of the DNP in the KPS. Since detailed research activities in each field of the DNP are introduced in other papers of this special issue, this review is focused on the main research groups, RISP (Rare Isotope Science Project) for the RAON accelerator, CENS (Center for Exotic Nuclear Studies) in the IBS (Institute of Basic Science) for the application of the RAON accelerator, CENuM (Center for Extreme Nuclear Matters) by the SRC (Scientific Research Center) Program, OMEG (Origin of Matter and Evolution of Galaxy) Institute by the Key Research Center in Universities Program, and other international research activities.

Short-Lived Radioisotope

The isotope ^{98}Tc decays to ^{98}Ru with a half-life of 4.2×10^{6} yr and could have been present in the early Solar System. In this Letter, we report on the first calculations of the production of ^{98}Tc by neutrino-induced reactions in core-collapse supernovae (the ν process). Our predicted ^{98}Tc 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 ^{98}Tc 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 ^{98}Tc ν-process nucleosynthesis is the large contribution (∼20%) from charged current reactions with electron antineutrinos. This means that ^{98}Tc becomes a unique new ν-process probe of the temperature of the electron antineutrinos.