Isospin symmetry ofTz=±3∕2→±1∕2Gamow-Teller transitions inA=

Abstract

Under the assumption that isospin T 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 =3/2 + ground state of 41 K leading to excited J =1/2 + , 3/2 + , and 5 / 2 + states in 41 Ca were measured using the ͑ 3 He, t͒ 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 ␤ decay 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 ␤-decay results. Combining the spectroscopic information of the analog states in 41 Ca and 41 Sc, the most probable J 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 Ϸ8 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 M1 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 ᐉ term in M1 transitions are small.

High-resolution study of Gamow-Teller transitions with the37Cl(3He,t)Shimbara1, Fujita2, Adachi3 et al. 2012Phys. Rev. CSelf Cite162150View full textAdd to dashboardCite

“…Also here, the strengths for the individual states are not necessarily in agreement and some levels have no corresponding pair in the mirror nucleus. A similar finding is reported for the T z = ±3/2 → ±1/2 GT transitions in the A = 41 system [24].…”

“…The excitation energies of 37 Ar were determined by the use of the well-known excitation energies of 13 N, 16 F, 18 F, 24 Al, 26 Al, 35 Ar, and 37 Ar. They were measured under the same conditions as the targets of MgO, 40 Ca 35 Cl 2 + PVA, and 40 Ca 37 Cl 2 + PVA.…”

“…They have relatively large Q EC values exceeding 10 MeV, which allows one to study not only the transitions to the low-lying states but also the main part of the GT transition strength at higher excitation energies. Fujita et al [24] extracted B(GT) values up to E x = 10.4 MeV in 41 Ca using the 41 K( 3 He, t) 41 Ca experiment and compared them to the B(GT) distribution obtained in the β decay of 41 Ti [25] to study the symmetry of the T = 3/2 system for A = 41 isobars. It was found that the overall B(GT) distributions of the two measurements were similar to each other up to 8 MeV.…”

High-resolution study of Gamow-Teller transitions in the47Ti(3He,t)Ganioğlu1, Fujita2, Fujita3 et al. 2013Phys. Rev. CSelf Cite

“…In Fig. 8, our 0 • spectrum is compared with the 41 K( 3 He, t) 41 Ca spectrum obtained at 0 • and at the same incoming energy of 140 MeV/nucleon at RCNP [53]. The scales of the ordinates are adjusted so that the states populated with the same B(GT) value have the same height in these two spectra.…”

High-resolution study ofTz=+1→0Gamow-Teller transitions in theMg26(He

“…Taking this accuracy into account, we can safely say that the Coulomb displacement energies (CDEs) of these high-E x states, and thus the binding conditions of these states, are largely dependent on their E x values. It has been discussed that CDE values are also dependent on the relevant configurations [54][55][56].…”