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The role of isospin symmetry in collective nuclear structure

Nature Physics volume 2, pages 311–318 (2006)Cite this article

Abstract

The nucleus is a unique laboratory in physics — a quantum many-body system comprising two types of fermion, the neutron and proton, differing in charge but otherwise essentially identical in their behaviour. The fact that the strong interaction between these fermions is largely independent of charge results in striking symmetries in nuclei. This neutron–proton exchange invariance is encompassed in the elegant concept and formalism of Wigner’s isotopic spin — or isospin. The impact of isospin symmetry is maximal near the N=Z line where nuclei have equal numbers of neutrons and protons, and studies involving isospin effects have undergone a resurgence in recent years as such nuclei become more readily accessible. In this review we discuss three isospin-related phenomena: the elegant isospin symmetry of excited analogue states in nuclei, the origin of the extra binding for nuclei with equal numbers of neutrons and protons and the exotic phenomenon of neutron–proton pairing. These three topics, all of considerable current interest, demonstrate the power, simplicity and modern relevance of the isospin concept.

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Acknowledgements

This work is supported by the UK Engineering and Physical Sciences Research Council.

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Authors and Affiliations

  1. CCLRC Daresbury Laboratory, Daresbury, Warrington WA4 4AD, UK

    D. D. Warner

  2. Department of Physics, University of York, Heslington, York YO10 5DD, UK

    M. A. Bentley

  3. GANIL, BP 55027, F-14076 Caen Cedex 5, France

    P. Van Isacker

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  1. D. D. Warner
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Correspondence to M. A. Bentley or P. Van Isacker.

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Tribute to Dave Warner Professor Dave Warner passed away suddenly during the preparation of this review. Following a D.Phil at the University of Sussex and periods spent at the Institut Laue-Langevin (France) and Brookhaven National Laboratory (USA), he was Head of the Surface and Nuclear Division at CCLRC Daresbury Laboratory. Dave’s understanding of isospin was instrumental in the development of the studies described in this article and many of the original ideas and insights explained here are due to him. In addition to this work, he was a leading proponent of algebraic and geometric approaches to nuclear modelling and, latterly, of UK involvement in the development of international radioactive nuclear beam facilities. He will be dearly missed as a physicist, colleague and friend.

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Warner, D., Bentley, M. & Isacker, P. The role of isospin symmetry in collective nuclear structure. Nature Phys 2, 311–318 (2006). https://doi.org/10.1038/nphys291

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