Bochum 1998 – scientific programme

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HK: Hadronen und Kerne

HK 22: Plenar

HK 22.1: Talk

Tuesday, March 17, 1998, 09:00–09:45, P

Nuclear Structure beyond the Driplines — •M. Thoennessen — Michigan State University

The availability of radioactive beams made the study of exotic nuclei along and even beyond the driplines possible. I will discuss a few selected examples of the decay of light nuclei along the proton and neutron dripline.

The search for di-proton emission with very short lifetimes (∼10−21s) has been performed in ¹²O and ¹⁷Ne. The observation of the ground state decay of ¹²O showed that the decay proceeds sequentially via an intermediate state of ¹¹N. However, the large decay width can only be explained by a level inversion of the ¹¹N ground state similar to the mirror nucleus ¹¹Be. The measurement of the γ-decay of the first excited state of ¹⁷Ne indicates that it is about 40% weaker than predicted theoretically, thus it might be possible that the remaining strength decays via the emission of a di-proton.

Along the neutron dripline the knowledge of the structure of the ground state of the neutron unbound nucleus ¹⁰Li is essential for the understanding of the two-neutron halo nucleus ¹¹Li. The giant dipole resonance in exotic nuclei was observed in ¹¹Be by intermediate energy Coulomb excitation and the subsequent γ-ray decay with a large array of BaF₂ detectors. In slightly heavier nuclei the search for neutron radioactivity in set new limits on the lifetime of ¹⁶B.

Further improvements of the capabilities of radioactive beam facilities will extend these studies to even heavier nuclei.