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HK: Hadronen und Kerne
HK 70: Plenar
HK 70.1: Gruppenbericht
Freitag, 20. März 1998, 11:30–12:00, P
Beta–Decay of Proton–Rich Nuclei — •E. Roeckl — GSI Darmstadt, Planckstr. 1, D–64291 Darmstadt, Germany
Considerable progress has recently been made in studying the β–decay of proton–rich (N≅Z) nuclei near the double shell–closures 40Ca, 56Ni, and 100Sn. The main motivations for these measurements are that (i) a few nucleons outside a doubly magic core are expected to represent comparatively simple configurations and thus to be useful for tests of nuclear–model predictions, and (ii) the large decay–energy window guarantees that most of the strength of allowed β–decay can be reached by the experiment.
The experiments, presented in this report, used secondary radioactive beams produced either by fragmentation reactions at the Projectile Fragment Separator (FRS) or by fusion–evaporation reactions at the Isotope Separator Online (ISOL) of GSI Darmstadt. Beta–delayed protons and γ–rays were measured. For the first time, both a (low–resolution) total absorption spectrometer and an array of six (high–resolution) EUROBALL CLUSTER detectors were used for recording β–delayed γ–rays. This has yielded unprecedented data quality of the β–intensity distributions measured for exotic nuclei near 100Sn.
Results are presented for FRS experiments of 36,37Ca [1] and 40Ti [2], which are also relevant to the calibration of the solar neutrino detectors using 37Cl and 40Ar, respectively, and for ISOL experiments on 56Cu [3], 97,98Ag [4], and 102,103In [5]. The experimental strength distributions for Fermi and Gamow–Teller decay are confronted to shell–model predictions, with particular emphasis being paid on the phenomenon of the quenching of the Gamow–Teller strength. Status and perspectives of these investigations, including the relation to the astrophysical rp–process, will be discussed.
[1] W. Trinder et al., Nucl. Phys. A 620, 191 (1997)
[2] W. Liu et al., Nucl. Phys. A 359, 1 (1997)
[3] W. Liu et al., contribition to this conference
[4] Z. Hu et al., Darmstadt–Valencia–Warsaw Collaboration, to be published
[5] M. Karny et al., Darmstadt–St. Petersburg–Valencia–Warsaw Collaboration, to be published