Atomic nuclei have a shell structure1 in which nuclei with ‘magic numbers’ of neutrons and protons are analogous to the noble gases in atomic physics. Only ten nuclei with the standard magic numbers of both neutrons and protons have so far been observed. The nuclear shell model is founded on the precept that neutrons and protons can move as independent particles in orbitals with discrete quantum numbers, subject to a mean field generated by all the other nucleons. Knowledge of the properties of single-particle states outside nuclear shell closures in exotic nuclei is important2,3,4,5 for a fundamental understanding of nuclear structure and nucleosynthesis (for example the r-process, which is responsible for the production of about half of the heavy elements). However, as a result of their short lifetimes, there is a paucity of knowledge about the nature of single-particle states outside exotic doubly magic nuclei. Here we measure the single-particle character of the levels in 133Sn that lie outside the double shell closure present at the short-lived nucleus 132Sn. We use an inverse kinematics technique that involves the transfer of a single nucleon to the nucleus. The purity of the measured single-particle states clearly illustrates the magic nature of 132Sn.

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This work was supported by the US Department of Energy under contract numbers DEFG02-96ER40995 (Tennessee Technological University (TTU)), DE-FG52-03NA00143 (Rutgers, Oak Ridge Associated Universities), DE-AC05-00OR22725 (Oak Ridge National Laboratory), DE-FG02-96ER40990 (TTU), DE-FG03-93ER40789 (Colorado School of Mines), DE-FG02-96ER40983 (University of Tennessee, Knoxville), DE-FG52-08NA28552 (Michigan State University (MSU)), DE-AC02-06CH11357 (MSU), the National Science Foundation under contract numbers NSF-PHY0354870 and NSF-PHY0757678 (Rutgers) and NSF-PHY-0555893 (MSU), and the UK Science and Technology Funding Council under contract number PP/F000715/1.

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  1. Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA

    • K. L. Jones
    • , K. Y. Chae
    • , R. Kapler
    • , Z. Ma
    •  & B. H. Moazen
  2. Department of Physics and Astronomy, Rutgers University, New Brunswick, New Jersey 08903, USA

    • K. L. Jones
    • , J. A. Cizewski
    • , R. Hatarik
    • , S. D. Pain
    •  & T. P. Swan
  3. Department of Physics and Astronomy, Ohio University, Athens, Ohio 45701, USA

    • A. S. Adekola
  4. Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA

    • D. W. Bardayan
    • , J. C. Blackmon
    • , J. F. Liang
    • , C. D. Nesaraja
    • , D. Shapira
    •  & M. S. Smith
  5. Physics Department, Colorado School of Mines, Golden, Colorado 80401, USA

    • K. A. Chipps
    • , L. Erikson
    •  & R. Livesay
  6. Department of Physics, University of Surrey, Guildford, Surrey GU2 7XH, UK

    • C. Harlin
    • , N. P. Patterson
    • , T. P. Swan
    •  & J. S. Thomas
  7. Department of Physics, Tennessee Technological University, Cookeville, Tennessee 38505, USA

    • R. L. Kozub
    •  & J. F. Shriner Jr
  8. National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA

    • F. M. Nunes


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K.L.J., D.W.B., J.C.B., J.A.C., R.L.K., J.F.L., C.D.N., S.D.P., D.S., M.S.S. and J.S.T. designed the experiment and developed the experimental tools and techniques. K.L.J., D.W.B., J.C.B., K.Y.C., R.H., R.L.K., J.F.L., B.H.M., S.D.P. and D.S. set up the experimental equipment, including new, unique detectors and associated electronics. K.L.J., D.W.B., J.C.B., K.Y.C., R.L.K., B.H.M., S.D.P., T.P.S. and J.S.T. developed online and offline analysis software routines and algorithms. K.L.J., A.S.A., D.W.B., J.C.B., K.Y.C., K.A.C., L.E., C.H., R.H., R.K., R.L.K., J.F.L., R.L., Z.M., B.H.M., C.D.N., S.D.P., N.P.P., D.S., J.F.S., M.S.S., T.P.S. and J.S.T. while running the experiment, assessed the quality and performed preliminary analyses of online data. K.L.J., K.Y.C., R.K., R.L.K., B.H.M., S.D.P. and T.P.S. analysed the data and calibrations. K.L.J., D.W.B., J.A.C., R.L.K., F.M.N. and S.D.P. interpreted the data, including theoretical calculations. K.L.J., J.A.C. and F.M.N. wrote the manuscript. K.L.J., D.W.B., J.C.B, K.A.C., J.A.C., R.L.K., J.F.L., F.M.N., S.D.P., J.F.S., M.S.S. and J.S.T. revised the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to K. L. Jones.

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    Supplementary information

    This file contains Supplementary Data, Supplementary Figures 4-5 with legends, Supplementary Tables 2-5 and References.

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