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HK: Physik der Hadronen und Kerne
HK 43: Nuclear Structure/Spectroscopy VII
HK 43.7: Talk
Thursday, March 11, 2004, 18:30–18:45, A
Studies of the l-forbidden ground state transition in 32S(d,2He)32P. — •E.-W. Grewe1, C. Bäumer1, A. van den Berg2, B. Davids2, D. Frekers1, D. de Frenne3, P. Haefner1, M.N. Harakeh2, M. Hunyadi2, E. Jacobs3, B. Junk1, A. Korff1, A. Negret3, P. von Neumann-Cosel4, L. Popescu3, S. Rakers1, and H.J. Wörtche2 — 1Institut für Kernphysik, Westfälische Wilhelms Universität Münster,D-48149 Münster, Germany — 2Kernfysisch Versneller Instituut, Rijksuniversiteit Groningen, NL-9747 AA Groningen, The Netherlands — 3Vakgroep Subatomaire en Stralingsfysica, Universiteit Gent, B-9000 Gent, Belgium — 4Institut für Kernphysik, Technische Universität Darmstadt, D-64289 Darmstadt, Germany
Two of the most hindered allowed beta decays in sd-shell nuclei are those for the mirror decays of the Jπ=1+ ground states of 32P and 32Cl to the ground state of 32S. In the simple shell-model this is described as a 1d3/2 → 2s1/2 transition and it may therefore be the best case for a study of l-forbidden strength towards the middle of the sd-shell. We employed the (d,2He)-probe to measure the l-forbidden 0+ → 1+ transition strength to the g.s. of 32P. The reaction calculation using DWBA and USD-wave functions reveals that the transition to the 32P g.s. is not governed by the central Vσ τ term, but rather dominated by the tensor force. A small contribution from the GT operator due to g.s. correlations gives rise to a B(GT+) = (2.7±1.3)×10−4. This value leads to log ft = 7.7±0.3, which is in agreement with the result from 32P β-decay, log ft = 7.9.
The (d,2He)-probe was compared to (p,n), (p,p′) and (e,e′) data and the A=32, Jπ = 1+ isospin triplet structure was deduced.