## Abstract

Under the assumption that isospin T is a good quantum number, isobaric analog states and various analogous transitions among these states are expected in isobars with mass number A. Strengths of analogous Gamow-Teller (GT) and M1 transitions have been compared for an A = 26 isobar triplet with T_{z}= +1, 0, and -1, where T_{z} is defined by T_{z} = (N-Z)/2. The T_{z}= + 1 → 0 GT transitions from the J^{π} = 0 ^{+}ground state of ^{26}Mg to excited J^{π}= 1 ^{+} states in ^{26}Al were studied up to the excitation energy (E_{x}) of 9 MeV by using a high energy-resolution (^{3}He,t) reaction. The distribution of observed GT strengths was well reproduced in a shell-model calculation. The isospin symmetric T_{z}= - 1 → 0 GT transitions can be studied in the ^{26}Si β decay. The GT strengths from the (^{3}He,t) reaction were in good agreement with the β-decay values evaluated up to E_{x} = 2.7-MeV states in ^{26}Al. The GT strengths were further compared with the strengths of analogous M1 γ transitions in ^{26}Al, i.e., the M1 transitions from the excited 1^{+} states to the isobaric analog state of the ^{26}Mg ground state in ^{26}Al. Through this comparison, contributions of spin and orbital terms in these Ml transitions were studied. The GT and M1 strengths as well as spin and orbital contributions in M1 strengths are interpreted by both the shell model and the particle-rotor model assuming a correlated proton and neutron pair around a ^{26}Mg core. The isospin T of each excited 1^{+} state in ^{26}Al was also studied by examining the existence or the nonexistence of the analog 1 ^{+} state in the T_{z} = 1 ^{26}Mg nucleus.

Original language | English |
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Article number | 064312 |

Pages (from-to) | 643121-6431212 |

Number of pages | 5788092 |

Journal | Physical Review C - Nuclear Physics |

Volume | 67 |

Issue number | 6 |

Publication status | Published - 2003 Jun |

## ASJC Scopus subject areas

- Nuclear and High Energy Physics

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