Köln 2004 – scientific programme

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HK: Physik der Hadronen und Kerne

HK 43: Nuclear Structure/Spectroscopy VII

HK 43.4: Talk

Thursday, March 11, 2004, 17:45–18:00, A

Gamow Teller strengths in beta+ and beta- directions starting from the ground state of 14N — •Alexandru Negret and Denis De Frenne — Universiteit Gent, Belgium

Although all the quantum numbers involved in the beta decay of 14C and 14O to the ground state of 14N (1+, T=0) suggest a Gamow Teller character, these transitions are strongly hindered. Theoretically [S. Aroua et al., Nucl.Phys. A720, 71 (2003)], the structure of the ground state of 14N seems to favor the transition to one 2+ state rather than to the 0+ or 1+ excited states in the final nuclei. This experimental study is addressing the issue of the Gamow Teller strength distribution starting from the ground state of 14N to the final excited states of 14C and 14O. An 14N(d,2He)14C experiment has been performed at the KVI-Groningen with the ESN setup and an 14N(3He,t)14O study has taken place at the RCNP-Osaka. We found that, indeed, in both cases, the g.s. - g.s. transitions are strongly hindered, while the strength is going mainly to three 2+ excited states. However, the fragmentation of the Gamow-Teller strengh over three 2+ excited states remains an open question for the theory. The striking similarities of the two resulting spectra (14C and 14O) observed in these two mirror experiments illustrate a good isospin symmetry.