Freiburg 1999 – wissenschaftliches Programm

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HK: Physik der Hadronen und Kerne

HK 25: Kernphysik IV / Exotische Kerne II

HK 25.2: Gruppenbericht

Dienstag, 23. März 1999, 17:00–17:30, B

Beta–Decay of Proton–Rich Nuclei Near ⁵⁶Ni — •R. Borcea¹, J. Äystö², P. Dendooven², M. Gierlik³, M. Górska¹, H. Grawe¹, M. Hellström⁴, Z. Janas³, A. Jokinen², M. Karny³, R. Kirchner¹, M. La Commara¹, P. Mayet¹, A. Nieminen², H. Penttilä², A. Plochocki³, M. Rejmund³, E. Roeckl¹, C. Schlegel¹, K. Schmidt¹, R. Schwengner⁵, and M. Sawicka³ — ¹GSI Darmstadt — ²University of Jyväskylä — ³Warsaw University — ⁴Lund University — ⁵FZ Rossendorf

Nuclei with a few nucleons outside a doubly–magic core represent comparatively simple configurations and thus are useful for tests of nuclear model predictions. Furthermore, the large decay–energy window, available for very proton–rich nuclei, guarantees that most of the strength of allowed β–decay can be reached by the experiment. Based on these motivations, the β–decay of proton–rich nuclei near the double shell–closure at ⁵⁶Ni, i.e. ⁵⁷Cu, ⁶¹Ga (T_z=-1/2), ⁵⁶Cu, ⁶⁰Ga (T_z=-1), and ⁵⁷Zn (T_z=-3/2), was investigated at the GSI Online Mass Separator by using ²⁸Si(³²S,xpyn) and ²⁸Si(³⁶Ar,xpyn) fusion–evaporation reactions. Beta–delayed protons were measured by means of a telescope consisting of a gas–ΔE and a silicon-E detector, whereas β–delayed γ–rays were measured by using a Euroball Cluster and a Segmented Clover detector. The quality of the data obtained for ⁵⁶Cu and ⁶¹Ga has been improved by two orders of magnitude over previous works [1,2]. Preliminary results will be discussed, in particular concerning the experimental strength distributions for Fermi and Gamow–Teller decay in comparison to shell–model predictions.

[1] M. Ramdhane et al., Phys. Lett. B 432, 22 (1998)

[2] M. Oinonen et al., Nucl. Phys. A, in print