Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Nuclear isomers in superheavy elements as stepping stones towards the island of stability


A long-standing prediction of nuclear models is the emergence of a region of long-lived, or even stable, superheavy elements beyond the actinides. These nuclei owe their enhanced stability to closed shells in the structure of both protons and neutrons1,2,3. However, theoretical approaches to date do not yield consistent predictions of the precise limits of the ‘island of stability’; experimental studies are therefore crucial. The bulk of experimental effort so far has been focused on the direct creation of superheavy elements in heavy ion fusion reactions, leading to the production of elements up to proton number Z = 118 (refs 4, 5). Recently, it has become possible to make detailed spectroscopic studies6,7 of nuclei beyond fermium (Z = 100), with the aim of understanding the underlying single-particle structure of superheavy elements. Here we report such a study of the nobelium isotope 254No, with 102 protons and 152 neutrons—the heaviest nucleus studied in this manner to date. We find three excited structures, two of which are isomeric (metastable). One of these structures is firmly assigned to a two-proton excitation. These states are highly significant as their location is sensitive to single-particle levels above the gap in shell energies predicted at Z = 114, and thus provide a microscopic benchmark for nuclear models of the superheavy elements.

This is a preview of subscription content, access via your institution

Relevant articles

Open Access articles citing this article.

Access options

Rent or buy this article

Get just this article for as long as you need it


Prices may be subject to local taxes which are calculated during checkout

Figure 1: Schematic illustration of the spherical single-proton orbitals in the region of superheavy elements.
Figure 2: Experimental data illustrating the decay of the two observed isomeric states.
Figure 3: Proposed level scheme of 254 No.
Figure 4: Suggested configurations of the 266 ms isomer.


  1. Ćwiok, S., Heenen, P.-H. & Nazarewicz, W. Shape coexistence and triaxiality in the superheavy nuclei. Nature 433, 705–709 (2005)

    Article  ADS  Google Scholar 

  2. Bender, M., Nazarewicz, W. & Reinhard, P.-G. Shell stabilization of super- and hyperheavy nuclei without magic gaps. Phys. Lett. B 515, 42–48 (2001)

    Article  ADS  CAS  Google Scholar 

  3. Bender, M., Rutz, K., Reinhard, P.-G., Maruhn, J. A. & Greiner, W. Shell structure of superheavy nuclei in self-consistent mean field models. Phys. Rev. C 60, 034304 (1999)

    Article  ADS  Google Scholar 

  4. Oganessian, Yu. Ts. et al. Measurements of cross sections and decay properties of the isotopes of elements 112, 114 and 116 produced in the fusion reactions 233,238U, 242Pu and 248Cm + 48Ca. Phys. Rev. C 70, 064609 (2004)

    Article  ADS  Google Scholar 

  5. Morita, K. et al. Experiment on the synthesis of element 113 in the reaction 209Bi(70Zn, n)278113. J. Phys. Soc. Jpn 73, 2593–2596 (2004)

    Article  ADS  CAS  Google Scholar 

  6. Leino, M. & Hessberger, F. P. The nuclear structure of heavy-actinide and transactinide nuclei. Annu. Rev. Nucl. Part. Sci. 54, 175–215 (2004)

    Article  ADS  CAS  Google Scholar 

  7. Herzberg, R.-D. Spectroscopy of superheavy nuclei. J. Phys. G 30, R123–R141 (2004)

    Article  CAS  Google Scholar 

  8. Hofmann, S. Synthesis of superheavy elements using radioactive beams and targets. Prog. Part. Nucl. Phys. 46, 293–302 (2001)

    Article  ADS  CAS  Google Scholar 

  9. Armbruster, P. On the production of superheavy elements. Annu. Rev. Nucl. Part. Sci 50, 411–479 (2000)

    Article  ADS  CAS  Google Scholar 

  10. Walker, P. M. & Dracoulis, G. Energy traps in atomic nuclei. Nature 399, 35–40 (1999)

    Article  ADS  CAS  Google Scholar 

  11. Xu, F. R., Zhao, E. G., Wyss, R. & Walker, P. M. Enhanced stability of superheavy nuclei due to high-spin isomerism. Phys. Rev. Lett. 92, 252501 (2004)

    Article  ADS  CAS  Google Scholar 

  12. Ghiorso, A., Eskola, K., Eskola, P. & Nurmia, M. Isomeric states in 250Fm and 254No. Phys. Rev. C 7, 2032–2036 (1973)

    Article  ADS  CAS  Google Scholar 

  13. Butler, P. A. et al. Conversion electron cascades in 254No. Phys. Rev. Lett. 89, 202501 (2002)

    Article  ADS  CAS  Google Scholar 

  14. Duguet, T., Bonche, P. & Heenen, P.-H. Rotational properties of 252,253,254No: influence of pairing correlations. Nucl. Phys. A 679, 427–440 (2001)

    Article  ADS  Google Scholar 

  15. Bender, M., Bonche, P., Duguet, T. & Heenen, P.-H. Skyrme mean-field study of rotational bands in transfermium isotopes. Nucl. Phys. A 723, 354–364 (2003)

    Article  ADS  Google Scholar 

  16. Afanasjev, A. V., Khoo, T. L., Frauendorf, S., Lalazissis, G. A. & Ahmad, I. Cranked relativistic Hartree-Bogoliubov theory: Probing the gateway to superheavy nuclei. Phys. Rev. C 67, 024309 (2003)

    Article  ADS  Google Scholar 

  17. Egido, J. L. & Robledo, L. M. Fission barriers at high angular momentum and the ground-state rotational band of the nucleus 254No. Phys. Rev. Lett. 85, 1198–1201 (2000)

    Article  ADS  CAS  Google Scholar 

  18. Reiter, P. et al. Ground-state band and deformation of the Z = 102 isotope 254No. Phys. Rev. Lett. 82, 509–512 (1999)

    Article  ADS  CAS  Google Scholar 

  19. Tandel, S. K. et al. K-isomers in 254No: probing single-particle energies and pairing strengths in the heaviest nuclei. Phys. Rev. Lett. (submitted)

  20. Leino, M. et al. Gas-filled recoil separator for studies of heavy elements. Nucl. Instrum. Meth. B 99, 653–656 (1995)

    Article  ADS  CAS  Google Scholar 

  21. Page, R. D. et al. The GREAT spectrometer. Nucl. Instrum. Methods B 204, 634–637 (2003)

    Article  ADS  CAS  Google Scholar 

  22. Jones, G. D. Detection of long-lived isomers in super-heavy elements. Nucl. Instrum. Methods A 488, 471–472 (2002)

    Article  ADS  CAS  Google Scholar 

  23. Eeckhaudt, S. et al. Evidence for non-yrast states in 254No. Eur. Phys. J. A 26, 227–232 (2005)

    Article  ADS  CAS  Google Scholar 

  24. Butler, P. A. et al. High K bands in mid-supershell nuclei. Acta Phys. Pol. B 34, 2107–2117 (2003)

    ADS  CAS  Google Scholar 

  25. Soloviev, V. G. Description of nonrotational states of 250Cf and 256Fm. Sov. J. Nucl. Phys. 54, 1232–1238 (1991)

    Google Scholar 

  26. Lazarev, Yu. A. Study of the stability of the ground states and K-isomeric states of fermium-250 and nobelium-254 against spontaneous fission. Phys. Scripta 39, 422–435 (1989)

    Article  ADS  CAS  Google Scholar 

  27. Hara, K. & Sun, Y. Projected shell model and high spin spectroscopy. Int. J. Mod. Phys. E 4, 637–785 (1995)

    Article  ADS  Google Scholar 

  28. Sun, Y. Theoretical description of K-isomers. AIP Conf. Proc. 819, 30–34 (2006)

    Article  ADS  CAS  Google Scholar 

  29. Sun, Y., Zhou, X. R., Long, G. L., Zhao, E. G. & Walker, P. M. Nuclear structure of 178Hf related to the spin-16, 31-year isomer. Phys. Lett. B 589, 83–88 (2004)

    Article  ADS  CAS  Google Scholar 

  30. Hessberger, F. P. GSI experiments on synthesis and nuclear structure investigations of heaviest nuclei. Int. J. Mod. Phys. E 15, 284–291 (2006)

    Article  ADS  CAS  Google Scholar 

Download references


We thank T. L. Khoo, S. K. Tandel, P. D. Stevenson and P. M. Walker for discussions. This work was supported by the EU Fifth Framework Programme ‘Improving Human Potential—Access to Research Infrastructure’ and the EU Sixth Framework Programme ‘Integrating Infrastructure Initiative—Transnational Access’ (EURONS). I.G.D., A.S. and M.V. acknowledge a European Community Marie Curie Fellowship. Support by the Academy of Finland under the Finnish Centre of Excellence Programme 2000–2005, and by the UK EPSRC, is gratefully acknowledged. This work was supported in part by the NSF and the US Department of Energy, Office of Nuclear Physics.

Author information

Authors and Affiliations


Corresponding author

Correspondence to R.-D. Herzberg.

Ethics declarations

Competing interests

Reprints and permissions information is available at The authors declare no competing financial interests.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Herzberg, RD., Greenlees, P., Butler, P. et al. Nuclear isomers in superheavy elements as stepping stones towards the island of stability. Nature 442, 896–899 (2006).

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI:

This article is cited by


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing