学術雑誌論文

学術雑誌論文

text

Physical Review C - Nuclear Physics. 2004, 70, p. 54311

Isospin symmetry of T_z =±3/2 →±1/2 Gamow-Teller transitions in A=41 nucllei

American Physical Society

英語

text

2004-11

https://doi.org/10.1103/PhysRevC.70.054311

Under the assumption that isospin I is a good quantum number, isobaric analog states and various analogous transitions are expected in isobars with mass number A. The strengths of T_z=+3/2→+1/2 analogous Gamow-Teller (GT) transitions and analogous M1 transitions within the A=41 isobar quartet are compared in detail. The T_z= +3/2+1/2 GT transitions from the J^π=3/2+ ground state of ^<41>K leading to excited J^π = 1/2^+, 3/2^+, and 5/2^+ states in ^<41>Ca were measured using the (^3He,t) charge-exchange reaction. With a high energy resolution of 35 keV, many fragmented states were observed, and the GT strength distribution was determined up to 10 MeV excitation energy (E_x). The main part of the strength was concentrated in the E_x =4-6 MeV region. A shell-model calculation could reproduce the concentration, but not so well details of the strength distribution. The obtained distribution was further compared with two results of ^<41>Ti βdecay studying the analogous T^z=-3/2→-1/2 GT strengths. They reported contradicting distributions. One-to-one correspondences of analogous transitions and analog states were assigned up to E_x=6 MeV in the comparison with one of these ^<41>Ti β-decay results. Combining the spectroscopic information of the analog states in ^<41>Ca and ^<41> Sc, the most probable J^π values were deduced for each pair of analog states. It was found that 5/2^+ states carry the main part of the observed GT strength, while much less GT strength was carried by 1/2^+ and 3/2^+ states. The gross features of the GT strength distributions for each J were similar for the isospin analogous T_z=±3/ 2→±1/2 transitions, but the details were somewhat different. From the difference of the distributions, isospin-asymmetry matrix elements of ≈8 keV were deduced. The Coulomb displacement energy, which is sensitive to the configuration of states, showed a sudden increase of about 50 keV at the excitation energy of 3.8 MeV. The strengths of several Ml transitions to the IAS in ^<41>Ca were compared with the strengths of analogous GT transitions. It was found that ratios of the M1 and GT transition strengths were similar, suggesting that the contributions of the lτ term in M1 transitions are small.

Y. Fujita, Y. Shimbara, T. Adachi, G.P.A. Berg, B.A. Brown, H. Fujita, K. Hatanaka, J. Kamiya, K. Nakanishi, Y. Sakemi, S. Sasaki, Y. Shimizu, Y. Tameshige, M. Uchida, T. Wakasa, M. Yosoi. Physical Review C - Nuclear Physics, 70, 54311, 2004 of publication. "Copyright (2004) by the American Physical Society.

27150

Isospin symmetry of T_z =±3/2 →±1/2 Gamow-Teller transitions in A=41 nucllei

American Physical Society

英語

2004-11

Physical Review C - Nuclear Physics

70

54311

https://doi.org/10.1103/PhysRevC.70.054311

https://hdl.handle.net/11094/27150