Tatsuya Adachi

Gamow–Teller transitions in exotic pf-shell nuclei relevant to supernova explosion

Gamow–Teller (GT) transitions starting from unstable pf-shell nuclei are of interest not only in nuclear physics, but also in astrophysics, e.g. in violent neutrino induced reactions at the core-collapse stage of type II supernovae. In the β-decay study of these pf-shell nuclei, half-lives can be measured rather accurately. On the other hand, in high-resolution (3He, t) charge-exchange reactions at 0°, individual GT transitions up to high excitations can be studied. Assuming the isospin symmetry for the strengths of Tz = ±1 → 0 analogous GT transitions, we present a unique merged analysis for the determination of absolute B(GT) values.

Gamow-Teller transitions in the Ni-64(He-3, t)Cu-64 reaction

In order to study the Gamow–Teller (GT) transitions in the fp-shell nucleus 64Cu, the 64Ni(3He, t)64Cu charge-exchange reaction was investigated at MeV/nucleon [1]. The outgoing tritons were momentum analysed by the Grand Raiden spectrometer at 0°. The very high energy resolution of 35 keV (FWHM) allowed the separation of individual levels in the excitation energy region from 0 to 3.5 MeV. An angular distribution analysis was performed for the observed transitions to these states. In addition to the ground state (g.s.), known to be a Jπ = 1+ GT state, several excited states showed L = 0 nature, making them candidates of GT states. At higher excitation energies, the level density becomes very high and a bump-like structure, the so-called GT Giant Resonance, dominates the spectrum.