High-resolution study of Gamow-Teller transitions in the ${}^{47}$Ti(${}^3\mathrm{He},t$)${}^{47}$V reaction

Given the importance of Gamow-Teller (GT) transitions in nuclear structure and astrophysical nuclear processes, we have studied $T_z=+3/2\to +1/2$, GT transitions starting from the ${}^{47}$Ti nucleus in the (${}^3\mathrm{He},t$) charge-exchange reaction at $0^{\circ }$ and at an intermediate incident energy of 140 MeV/nucleon. The experiments were carried out at the Research Center for Nuclear Physics (RCNP), Osaka, using the high-resolution facility with a high-dispersion beam line and the Grand-Raiden spectrometer. With an energy resolution of 20 keV, individual GT transitions were observed and GT strength was derived for each state populated up to an excitation energy ($E_x$) of 12.5 MeV. The GT strength was widely distributed from low excitation energy up to 12.5 MeV, where we had to stop the analysis because of the high level density. The distribution of the GT strengths was compared with the results of shell model calculations using the GXPF1 interaction. The calculations could reproduce the experimental GT distributions well. The GT transitions from the ground state of ${}^{47}$Ti and the $M1$ transitions from the isobaric analog state in ${}^{47}$V to the same low-lying states in ${}^{47}$V are analogous. It was found that the ratios of GT transition strengths to the ground state, the 0.088-MeV state, and the 0.146-MeV state are similar to the ratios of the strengths of the analogous $M1$ transitions from the isobaric analog state (IAS) to these states. The measured distribution of the GT strengths was also compared with those starting from the $T_z=+3/2$ nucleus ${}^{41}$K to the $T_z=+1/2$ nucleus ${}^{41}$Ca.

Figure 1

The ${}^{47}$Ti(${}^3\mathrm{He},t$)${}^{47}$V spectrum at $0^{\circ }$. Events with scattering angles $\Theta \le 0.5^{\circ }$ are included. Prominent states populated in $\Delta L=0$ transitions are indicated by their excitation energies.

Figure 2

Part of the ${}^{47}$Ti(${}^3\mathrm{He},t$)${}^{47}$V spectrum shown in Fig. 1 for $0\le$ $E_x$ $\le$ 4 MeV. Prominent states populated in $\Delta L=0$ transitions are indicated by their excitation energies. States in ${}^{48}$V are also indicated.

Figure 3

Part of the ${}^{47}$Ti(${}^3\mathrm{He},t$)${}^{47}$V spectrum shown in Fig. 1 for 4 $\le$ $E_x$ $\le$ 8 MeV. Prominent states populated in $\Delta L=0$ transitions are indicated by their excitation energies. In the region $E_x$ $\le$ 6.7 MeV, newly observed states that are clearly populated in $\Delta L=0$ transitions are indicated by arrows. States of ${}^{48}$V are also shown.

Figure 4

Part of the ${}^{47}$Ti(${}^3\mathrm{He},t$)${}^{47}$V spectrum shown in Fig. 1 for 8 $\le$ $E_x$ $\le$ 12 MeV. Prominent states populated in $\Delta L=0$ transitions are indicated by their excitation energies.

Figure 5

A comparison of the experimental and theoretical $B$(GT) strength distributions with (a) the $B$(GT) distribution derived from the ${}^{47}$Ti(${}^3\mathrm{He},t$)${}^{47}$V measurement and (b) the $B$(GT) distribution from the SM calculation.

Figure 6

A comparison of the summed $B$(GT) strengths from the ${}^{47}$Ti(${}^3\mathrm{He},t$)${}^{47}$V measurement (solid line) and the SM calculation using the GXPF1 interaction (dotted line) as a function of excitation energy.

Figure 7

Schematic view of the isospin analog states and analogous transitions in the $A=47$, $T_z=+3/2$ and $+1/2$ isobaric system. The Coulomb displacement energies are removed so that the isospin symmetry of the states and transitions becomes clearer. The type of the reaction or decay is shown alongside the arrow indicating the transition.

Figure 8

Comparison of (a) the ${}^{41}$K(${}^3\mathrm{He},t$)${}^{41}$Ca spectrum and (b) the ${}^{47}$Ti(${}^3\mathrm{He},t$)${}^{47}$V spectrum measured at 140 MeV/nucleon and $0^{\circ }$. The scales of the ordinates are adjusted so that the states with the same $B$(GT) value have the same height in these two spectra.