Analogous Gamow-Teller and M1 Transitions in T _z = ±? Mirror Nuclei and in T _z = ±1, 0 Triplet Nuclei relevant to Low-energy Super GT state

摘要

Nuclei have spin- and isospin-degrees of freedom. Therefore, Gamow-Teller (GT) transitions caused by the στ operator (spin-isospin operator) are unique tools for the studies of nuclear structure as well as nuclear interactions. They can be studied in β decays as well as charge-exchange (CE) reactions. Similarly, M 1 γ decays are mainly caused by the στ operator. Combined studies of these transitions caused by Weak, Strong, and Electro-Magnetic interactions provide us a deeper understanding of nuclear spin-isospin-type transitions. We first compare the strengths of analogous GT and M 1 transitions in the A = 27, T_(z) = ±? mirror nuclei~(27)Al and~(27)Si. The comparison is extended to the T_(z) = ±1, 0 nuclei. The strength of GT transition from the ground state (g.s.) of~(42)Ca to the 0.611 MeV first J~(π) = 1~(+)state in~(42)Sc is compared with that of the analogous M 1 transition from the 0.611 MeV state to the T = 1, 0~(+)g.s. (isobaric analog state: IAS) in~(42)Sc. The 0.611 MeV state has the property of Low-energy Super GT (LeSGT) state, because it carries the main part of the GT strength of all available transitions from the g.s. of~(42)Ca (and~(42)Ti) to the J~(π) = 1~(+)GT states in~(42)Sc.