Analogous Gamow-Teller andM1transitions in26Mg,26Al,and26Si
Analogous Gamow-Teller andM1transitions in26Mg,26Al,and26Si
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26Mg、26Al 和 26Si 中的类似伽莫夫泰勒和 M1 转变
DOI：
10.1103/physrevc.67.064312
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发表时间：
2003
影响因子：
3.1
通讯作者：
M. Yosoi
中科院分区：
文献类型：
--
作者：
Y. Fujita;Y. Shimbara;A. Lisetskiy;T. Adachi;G. Berg;P. Brentano;H. Fujimura;H. Fujita;K. Hatanaka;J. Kamiya;T. Kawabata;H. Nakada;K. Nakanishi;Y. Shimizu;M. Uchida;M. Yosoi
在假设同位旋T是一个好量子数的条件下，质量数为A的同量异位素中可能存在同量异位素类似态以及这些态之间的各种类似跃迁。对于一个A= 26的等压线三重态，T z=+1，0和− 1，其中T z定义为T z=（N-Z）/2，我们比较了类似的伽莫夫-泰勒（GT）和M1跃迁的强度。利用高能量分辨（3 He，t）反应研究了26 Mg基态J π= 0+到26 Al激发态J π= 1+的Tz =+ 1→ 0 GT跃迁，激发能（Ex）为9 MeV.观察到的GT强度的分布在壳模型计算中得到很好的再现。可以在26 Si β衰变中研究Isospin对称T z=-1 → 0 GT跃迁。来自（3 He，t）反应的GT强度与26 Al中高达E x= 2.7− MeV状态的β衰变值非常一致。GT强度进一步与26 Al中类似的M 1 γ跃迁的强度进行了比较，即，M1从激发的1+态跃迁到26 Al中26 Mg基态的同量异位素类似态。通过这种比较，研究了自旋项和轨道项在这些M1跃迁中的贡献。GT和M1强度以及自旋和轨道的贡献M1强度解释的壳模型和粒子转子模型假设相关的质子和中子对周围的24镁核心。通过考察Tz = 1 2 6 Mg核中类似1+态的存在与否，研究了2 6 Al中各激发态的同位旋T.
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 M 1 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 M 1 γ transitions in 26 Al, ie, the M 1 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 M 1 transitions were studied. The GT and M 1 strengths as well as spin and orbital contributions in M 1 strengths are interpreted by both the shell model and the particle-rotor model assuming a correlated proton and neutron pair around a 24 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.