LABORATORI NAZIONALI DI LEGNARO
Gamow-Teller (GT) transitions play key roles in the studies of nuclear structure as well as astrophysical processes. In the pf-shell nuclei, they are of importance in the core-collapse stage of supernovae and the rp-process. We report the study of GT transitions from the Tz=+3/2, 47Ti nucleus to the states in Tz=+1/2, 47V nucleus by the (3He,t) reaction. The experiment was carried out at the Research Center for Nuclear Physics (RCNP), Osaka [1] using a 3He beam of 140 MeV/nucleon [2-5]. An excellent energy resolution of 20 keV was achieved by applying the dispersion matching techniques. We could study GT transitions to individual states up to 12.5 MeV in 47V. In order to determine the strength of each transition, it was assumed that the GT transition strength B(GT) is proportional to the measured differential cross-section at 0° in the (3He,t) reaction [6]. Since a “standard B(GT) value” is available from the study of 47V b decay, B(GT) values were reliably derived. The observed GT strength spreads widely up to 12.5 MeV and are highly fragmented. These features were very different from the “compact” GT strength distribution observed in the 41K(3He,t)41Ca reaction having the same Tz=+3/2à+1/2 nature [7]. The GT strength distribution in 47V was well reproduced by the shell-model calculations. The GT transitions from the ground state of 47Ti to the three low-lying states in 47V and the M1 transitions from the isobaric analog state in 47V to the same low-lying states in 47V are analogous. It was found that the ratios of the strengths of these analogous GT and M1 transitions were similar.

DATA: 25-01-2013