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HK: Physik der Hadronen und Kerne
HK 3: Nuclear Physics / Spectroscopy I
HK 3.2: Gruppenbericht
Montag, 11. März 2002, 16:45–17:15, B
Decay properties of N≃ nuclei: A status report from the ISOL facility of GSI — •J. Döring — GSI, Darmstadt, Germany
Nuclei with N≃Z between the double shell closures 56Ni and 100Sn are of great interest due to their special nuclear-structure features, including shape coexistence, the influence of the proton drip-line, tests of the Standard Model of Weak Interaction by means of precision data on superallowed 0+→0+ β-decays, and the relevance to the astrophysical rp process. These motivations form the basis of the research program pursued at the ISOL facility of GSI Darmstadt. After describing the fusion-evaporation reactions, used for producing the neutron-deficient isotopes of interest, and the detectors for decay measurements, we present examples of recent experiments, i.e. (i) the β-delayed proton emission from 57Zn (T1/2 = 38±4 ms) to 56Ni [1], (ii) the accurate determination of the branching ratio for the 58Cu(1+)→58Ni(0+) β transition (81.2±0.5 %), which serves as a calibration in deducing the Gamow-Teller strength distribution from high-resolution 58Ni(3He,t)58Cu data [2], and (iii) an attempt to reach a precision of 4 parts in 104 for the half-life of the superallowed 0+→0+ β-decay of 62Ga by accumulating about 2×106 positron events. Finally, an outlook will be given, including in particular the novel technique of extracting short-lived tin isotopes as singly charged sulfide molecules from the ion source, which opens exciting perspectives for future β-decay experiments on 102Sn and 100Sn.
[1] A. Jokinen et al., submitted to Eur. Phys. J. A.
[2] Z. Janas et al., Eur. Phys. J. A 12, 143 (2001).