High-resolution study of Tz=+1→0 Gamow-Teller transitions in the Mg 26 (He 3,t) Al 26 reaction

Kalayar Win, Y. Fujita, Yee Yee Oo, H. Fujita, Y. F. Niu, T. Adachi, G. P.A. Berg, G. Colò, H. Dohmann, M. Dozono, D. Frekers, E. W. Grewe, K. Hatanaka, D. Ishikawa, R. Kehl, N. T. Khai, Y. Kalmykov, H. Matsubara, P. Von Neumann-Cosel, T. NiizekiT. Ruhe, Y. Shimbara, K. Suda, A. Tamii, J. Thies, H. P. Yoshida

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2 Citations (Scopus)

Abstract

In order to study the Tz=+1→0 Gamow-Teller (GT) transitions in the mass A=26 system, a charge-exchange reaction Mg26(He3,t)Al26 was performed at an incident energy of 140 MeV/nucleon and scattering angle at and near 0, where Tz is the z component of isospin T defined by (N-Z)/2. In this (p,n)-type reaction, it is expected that GT states with T=0, 1, and 2 are excited. An energy resolution of ΔE=23 keV allowed us to study many discrete states. Most of the prominent states showed 0-peaked angular distributions, which suggested that they are the states excited by ΔL=0 GT transitions. Candidates of GT states were studied up to an excitation energy Ex=18.5 MeV. The reduced GT transition strengths, B(GT), were derived assuming the proportionality between cross sections and B(GT) values. Standard B(GT) values were obtained form the Si26β decay, where the mirror symmetry of Tz=±1→0 GT transitions was assumed. The GT strength, as a whole, is divided in two energy regions: the region of up to 8.5 MeV and the higher-energy region of 8.5-12.8 MeV, where the strength in the latter region distributed like a resonance. The obtained GT strength distribution is compared with the results of random phase approximation calculations. The T=2 GT states are expected in the region Ex≥13.5 MeV. By comparing with the results of (n,p)-type Mg26(d,He2)Na26 and Mg26(t,He3)Na26 reactions, the isospin symmetry of T=2 GT states is discussed. Owing to the high-energy resolution, we could study the decay widths Γ for the states in the Ex>9 MeV region. The T=2 state at 13.592 MeV is not noticeably wider than the experimental energy resolution. The narrow width of the state is explained in terms of isospin selection rules.

Original languageEnglish
Article number064309
JournalPhysical Review C
Volume96
Issue number6
DOIs
Publication statusPublished - 07-12-2017
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics

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