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Suppression of Gamow-Teller and M1 transitions in deformed mirror nuclei Mg-25 and Al-25 - Direct observation of K selection rules

Shimbara, Y; Fujita, Y; Adachi, T; Berg, GPA; Fujita, H; Fujita, K; Hamamoto-Kuroda, Ikuko LU ; Hatanaka, K; Kamiya, J and Nakanishi, K, et al. (2004) In European Physical Journal A. Hadrons and Nuclei1998-01-01+01:00 19(1). p.25-31
Abstract
The mirror nuclei Mg-25 and Al-25 are expected to have very similar structures. The Gamow-Teller (GT) transitions from the J(pi) = 5/2(+) ground state of Mg-25 to the excited states in Al-25 were studied by high-resolution measurements of the Mg-25(He-3,t) charge-exchange reaction at 0degrees and at 140 MeV/nucleon. Assuming the usual DeltaJ(pi) = 1(+) selection rule for the spin-isospin-type GT transitions, the states with J(pi) = 3/2(+), 5/2(+), and 7/2 (+) should be excited. However, of the more than ten states with these J(pi) values below 6 MeV excitation energy, only the 5/2 (+) ground state and the 7/2 (+) , 1.613 MeV state in Al-25 were strongly populated, while all other states were strongly suppressed. The analysis of M1... (More)
The mirror nuclei Mg-25 and Al-25 are expected to have very similar structures. The Gamow-Teller (GT) transitions from the J(pi) = 5/2(+) ground state of Mg-25 to the excited states in Al-25 were studied by high-resolution measurements of the Mg-25(He-3,t) charge-exchange reaction at 0degrees and at 140 MeV/nucleon. Assuming the usual DeltaJ(pi) = 1(+) selection rule for the spin-isospin-type GT transitions, the states with J(pi) = 3/2(+), 5/2(+), and 7/2 (+) should be excited. However, of the more than ten states with these J(pi) values below 6 MeV excitation energy, only the 5/2 (+) ground state and the 7/2 (+) , 1.613 MeV state in Al-25 were strongly populated, while all other states were strongly suppressed. The analysis of M1 transitions in Mg-25 also suggested a very similar feature for the analogous M1 transitions. Both Mg-25 and Al-25 are known to be largely deformed, and most low-lying states can be interpreted in terms of one-particle quantum numbers in the deformed potential and the associated rotational spectra. The observed suppression can be explained in terms of the K quantum number selection rules that are inherent to axially deformed nuclei. (Less)
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European Physical Journal A. Hadrons and Nuclei1998-01-01+01:00
volume
19
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1
pages
25 - 31
publisher
Springer
external identifiers
  • wos:000188207800004
  • scopus:0942289739
ISSN
1434-6001
DOI
10.1140/epja/i2003-10115-2
language
English
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yes
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8b0bd0a5-d657-4197-9b98-945c207b9531 (old id 289749)
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2007-10-26 13:56:14
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@article{8b0bd0a5-d657-4197-9b98-945c207b9531,
  abstract     = {The mirror nuclei Mg-25 and Al-25 are expected to have very similar structures. The Gamow-Teller (GT) transitions from the J(pi) = 5/2(+) ground state of Mg-25 to the excited states in Al-25 were studied by high-resolution measurements of the Mg-25(He-3,t) charge-exchange reaction at 0degrees and at 140 MeV/nucleon. Assuming the usual DeltaJ(pi) = 1(+) selection rule for the spin-isospin-type GT transitions, the states with J(pi) = 3/2(+), 5/2(+), and 7/2 (+) should be excited. However, of the more than ten states with these J(pi) values below 6 MeV excitation energy, only the 5/2 (+) ground state and the 7/2 (+) , 1.613 MeV state in Al-25 were strongly populated, while all other states were strongly suppressed. The analysis of M1 transitions in Mg-25 also suggested a very similar feature for the analogous M1 transitions. Both Mg-25 and Al-25 are known to be largely deformed, and most low-lying states can be interpreted in terms of one-particle quantum numbers in the deformed potential and the associated rotational spectra. The observed suppression can be explained in terms of the K quantum number selection rules that are inherent to axially deformed nuclei.},
  author       = {Shimbara, Y and Fujita, Y and Adachi, T and Berg, GPA and Fujita, H and Fujita, K and Hamamoto-Kuroda, Ikuko and Hatanaka, K and Kamiya, J and Nakanishi, K and Sakemi, Y and Shimizu, Y and Uchida, M and Wakasa, T and Yosoi, M},
  issn         = {1434-6001},
  language     = {eng},
  number       = {1},
  pages        = {25--31},
  publisher    = {Springer},
  series       = {European Physical Journal A. Hadrons and Nuclei1998-01-01+01:00},
  title        = {Suppression of Gamow-Teller and M1 transitions in deformed mirror nuclei Mg-25 and Al-25 - Direct observation of K selection rules},
  url          = {http://dx.doi.org/10.1140/epja/i2003-10115-2},
  volume       = {19},
  year         = {2004},
}