Mirror-symmetry structure of A=27, T=1/2 nuclei studied through strong, weak, and electromagnetic interactions

Gamow-Teller (GT) transitions and MI transitions from or to the ground stat es are analogous in the pair of T= 1/2 mirror nuclei, if the excited states hold the mirror-symmetry properties. In order to study the mirror-symmetry structure of the A = 27 mirror nuclei Al-27 and Si-27, experimental data o n GT transition strengths obtained from Si-27-->Al-27 beta decay and from a good-resolution Al-27(He-3,t)Si-27 reaction at 150 MeV/nucleon and 0 degre es have been compared with M1 transition strengths obtained from gamma deca y in Al-27 and Al-27(gamma,gamma') reaction. Good overall correspondence of transitions is observed for states up to nearly 9 MeV in excitation energy , where the particle-decay channel becomes Important. The difference of exc itation energies of analog states in the mirror nuclei are about: 250 keV a t this excitation energy. From a comparison of B(MI) and B(GT) strengths of the analogous transitions, the contribution of the isoscalar and the orbit al terms in the M1 operator is found to become prominent in weak M1 transit ions. [S0556-2813(99)03601-8].