Isospin Symmetry in the Structure Study of Unstable Nuclei

Assuming isospin T is a good quantum number, the analog states of the low-lying states in T-z = +/-(T-0 + 1) nuclei can be found as excited T-0 + 1 states in T-z = +/-T-0 nuclei. Therefore, if T-0 + 1 states are identified in the excited region of T-z = +/-T-0 nuclei, the structure of unstable nuclei with T-z = +/-(T-0 + 1) can be deduced. We measured and compared the transition strengths to pairs of excited analog states in inelastic and charge-exchange reactions on the same target nucleus. The T values of these analog states were identified by using the fact that the transition strengths to them are different depending on T. The identification of T = 1/2 and 3/2 nature of analog M1 and GT states in the mirror nuclei pair Al-27 and Si-27 is reported by comparing the transition strengths in high-resolution Al-27(p,p') and Al-27 (He-3, t) Si-27 reactions at 0degrees. The identified T = 3/2 states are analogous to the low-lying states of Mg-27, which plays an important role in rp-process of nucleosynthesis.