Photo‐nuclear astrophysics in NewSUBARU γ‐ray source

A laser Compton scattering (LCS) γ‐ray source has been installed at an electron storage ring NewSUBARU at SPring‐8. We have studied the nuclear physics using this LCS g‐ray source. The half‐lives of unstable isotopes, $184Re$ and $164Hom,$ produced by photo‐induced reactions have been measured. These half‐lives are shorter than previous recommended values by 7% and 3%, respectively. These changes of the half‐lives affects to evaluation of cross‐sections using the activation method. We have discussed a problem of the residual ratio of an isomer in $180Ta$ in supernova explosions. The unstable ground state and the metastable isomer are linked by (γ, γ’) reactions. We have developed a new time‐dependent model to calculate the isomer ratio in supernovae. The solar abundance of $180Ta$ is reproduced by the supernova neutrino process with the present calculated isomer ratio.