High-resolution study of theBe9(He3,t)B9reaction up to theB9triton threshold

Abstract

A high-energy-resolution $^{9}\mathrm{Be}$($^{3}\mathrm{He}$,$t$)$^{9}\mathrm{B}$ charge-exchange reaction was performed around a scattering angle of ${0}^{\ifmmode^\circ\else\textdegree\fi{}}$ and at an intermediate incident energy of 140 MeV/nucleon for the study of precise Gamow-Teller (GT) transition strengths. The energy resolution of 30 keV allowed a precise deconvolution of the spectrum and the determination of angular distributions of cross sections, excitation energies, and decay widths. The GT strength of 10 states has been determined for the first time using the GT strength of the analogous $\ensuremath{\beta}$ decays of $^{9}\mathrm{Li}$ and $^{9}\mathrm{C}$ as standards. The large difference between the GT strengths going to the low-lying $T=1/2$ and the highly excited $T=3/2$ states is interpreted as a result of their different spatial structures. The obtained GT strength distribution is compared to the results of a ($p$,$n$) experiment with lower resolution performed in the 1980s. In particular, the width of the 16.8 MeV, ${J}^{\ensuremath{\pi}}=(5/{2}^{+}$) state has been determined for the first time.