Isospin structure of $J^{\pi}=1^{+}$ states in $^{58}$Ni and $^{58}$Cu studied by $^{58}$Ni(p,p') and $^{58}$Ni(^{3}He,t)$^{58}$Cu measurements

Isospin is a good quantum number under the assumption that the nuclear interaction is charge independent. An analogous structure of excited states is expected for nuclei with the same mass number A but with different z components T_z of the isospin T, where T_z=(N-Z)/2. The analogous structure has been studied for the isobaric nuclei $^{58}$Ni and $^{58}$Cu by comparing the transitions from the $^{58}$Ni ground state (initial isospin T_i=1 and J^\pi=0^+) to the M1 and the Gamow-Teller (GT) states (J^\pi=1^+) in $^{58}$Ni and $^{58}$Cu, respectively. For this purpose, proton inelastic scattering (p,p') at E_p=160 MeV and the charge-exchange (^{3}He,t) reaction at 140 MeV/nucleon were both measured at 0°, exciting final states with isospin T_f=1 and 2 and T_f=0, 1, and 2, respectively. High energy and scattering-angle resolutions were achieved by applying complete beam matching techniques. On the basis of the correspondence between excitation energies and transition strengths, isospin values T_f=1 and 2 of analog GT and M1 states were identified. The distribution of T_f=2 states was also compared with results of $^{58}$Ni(d,^{2}He), $^{58}$Ni(t,^{3}He), and $^{58}$Ni(n,p) experiments, in which only T_f=2 states are excited. The obtained GT strength distribution is compared with the results of shell-model calculations.