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Synthesis of nuclei of the superheavy element 114 in reactions induced by 48Ca

Abstract

The stability of heavy nuclides, which tend to decay by α-emission and spontaneous fission, is determined by the structural properties of nuclear matter. Nuclear binding energies and lifetimes increase markedly in the vicinity of closed shells of neutrons or protons (nucleons), corresponding to ‘magic’ numbers of nucleons; these give rise to the most stable (spherical) nuclear shapes in the ground state. For example, with a proton number of Z = 82 and a neutron number of N = 126, the nucleus 208Pb is ‘doubly-magic’ and also exceptionally stable. The next closed neutron shell is expected at N = 184, leading to the prediction of an ‘island of stability’ of superheavy nuclei, for a broad range of isotopes with Z = 104 to 120 (refs 1, 2). The heaviest known nuclei have lifetimes of less than a millisecond, but nuclei near the top of the island of stability are predicted to exist for many years. (In contrast, nuclear matter consisting of about 300 nucleons with no shell structure would undergo fission within about 10−20 seconds.) Calculations3,4,5 indicate that nuclei with N > 168 should already benefit from the stabilizing influence of the closed shell at N = 184. Here we report the synthesis of an isotope containing 114 protons and 173 neutrons, through fusion of intense beams of 48Ca ions with 242Pu targets. The isotope decays by α-emission with a half-life of about five seconds, providing experimental confirmation of the island of stability.

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Figure 1: Theoretical predictions for partial half-lives of isotopes.
Figure 2: The electrostatic recoil separator VASSILISSA.
Figure 3: Position-correlated decay chains.

References

  1. Myers, W. D. & Swiatecki, W. J. Nuclear masses and deformations. Nucl. Phys. A 81, 1–60 (1966).

    CAS  Article  Google Scholar 

  2. Nix, J. R. Calculation of fission barriers for heavy and superheavy nuclei. Annu. Rev. Nucl. Sci. 22, 65–120 (1972).

    ADS  CAS  Article  Google Scholar 

  3. Smolańczuk, R., Skalski, J. & Sobiczewski, A. in Proc. Int. Workshop XXIV on Gross Properties of Nuclei and Nuclear Excitations “Extremes of Nuclear Structure” (eds Feldmeier, H., Knoll, J. & Nörenberg, W.) 35–42 (GSI, Darmstadt, (1996).

    Google Scholar 

  4. Smolańczuk, R. Properties of the hypothetical spherical superheavy nuclei. Phys. Rev. C 56, 812–824 (1997).

    ADS  Article  Google Scholar 

  5. Möller, P., Nix, J. R. & Kratz, K.-L. Nuclear properties for astrophysical and radioactive-ion-beam applications. Atom. Data Nucl. Data Tables 66, 131–134 (1997).

    ADS  Article  Google Scholar 

  6. Oganessian, Yu. Ts. in Proc. Int. Conf. on Nuclear Physics at the Turn of the Millennium “Structure of Vacuum and Elementary Matter” (eds Stocker, H., Gallmann, A. & Hamilton, J. H.) 11–24 (World Scientific, Singapore, (1997).

    Google Scholar 

  7. Pustylnik, B. I. in Proc. VI Int. School-Seminar “Heavy Ion Physics” (eds Oganessian, Yu. Ts. & Kalpakchieva, R.) 431–433 (World Scientific, Singapore, (1998).

    Google Scholar 

  8. Wada, T. et al. in Proc. Int. Conf. on Dynamical Aspects on Nuclear Fission (eds Oganessian, Yu. Ts. & Kliman, J.) (World Scientific, Singapore, (1999).

    Google Scholar 

  9. Gregorich, K. E. et al. First confirmation of the discovery of element 106. Phys. Rev. Lett. 72, 1423–1426 (1994).

    ADS  CAS  Article  Google Scholar 

  10. Schädel, M. et al. Chemical properties of element 106 (seaborgium). Nature 388, 55–57 (1997).

    ADS  Article  Google Scholar 

  11. Lazarev, Yu. A. et al. αdecay of 273110: shell closure at N = 162. Phys. Rev. C 54, 620–625 (1996).

    ADS  CAS  Article  Google Scholar 

  12. Blocki, J. P., Feldmeier, H. & Swiatecki, W. J. Dynamical hindrance to compound-nucleus formation in heavy-ion reactions. Nucl. Phys. A 459, 145–172 (1986).

    ADS  Article  Google Scholar 

  13. Hulet, E. K. et al. Search for superheavy elements in the bombardment of 248Cm with 48Ca. Phys. Rev. Lett. 39, 385–389 (1977).

    ADS  CAS  Article  Google Scholar 

  14. Oganessian, Yu. Ts. et al. Experiments to produce isotopes of superheavy elements with atomic numbers 114–116 in 48Ca ion reactions. Nucl. Phys. A 294, 213–224 (1978).

    ADS  Article  Google Scholar 

  15. Armbruster, P. et al. Attempts to produce superheavy elements by fusion of 48Ca with 248Cm in the bombarding energy range of 4.5–5.2 MeV/u. Phys. Rev. Lett. 54, 406–409 (1985).

    ADS  CAS  Article  Google Scholar 

  16. Oganessian, Yu. Ts. et al. Search for new isotopes of element 112 by irradiation of 238U with 48Ca. Eur. Phys. J. A 5, 63–68 (1999).

    ADS  CAS  Article  Google Scholar 

  17. Hofmann, S. et al. The new element 112. Z. Phys. A 354, 229–230 (1996).

    ADS  CAS  Article  Google Scholar 

  18. Oganessian, Y. Ts. et al. The synthesis of superheavy nuclei in the 48Ca + 244Pu reaction. Phys. Rev. Lett. (submitted); also as preprint E7-99-53 (JINR, Dubna, (1999).

  19. Kutner, V. B. et al. in Proc. 15th Int. Conf. on Cyclotrons and Their Applications (eds Baron, E. & Lieuvin, M.) 405–408 (IOP, Bristol, (1998).

    Google Scholar 

  20. Yeremin, A. V. et al. The kinematic separator VASSILISSA performance and experimental results. Nucl. Instrum. Meth. A 350, 608–617 (1994).

    ADS  CAS  Article  Google Scholar 

  21. Schmidt, K.-H. et al. Some remarks on the error analysis in the case of poor statistics. Z. Phys. A 316, 19–26 (1984).

    ADS  CAS  Article  Google Scholar 

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Acknowledgements

We thank the JINR Directorate, in particular Ts. Vylov, V. G. Kadyshevsky and A.N.Sissakian, for help and support; V. Ya. Lebedev and S. N. Dmitriev for the preparation of metal Ca samples for the ECR-ion source; A. N. Shamanin and E. N. Vornokov for help in the maintenance of the recoil separator; G. Münzenberg, A. Sobiczewski and R. Smolańczuk for discussions; the staff of the U-400 Cyclotron for assistance; and V. N. Loginov, A. N. Lebedev, and the ion source group staff for obtaining the intense 48Ca beam. This work was supported by the Russian Foundation for Basic Research and the INTAS, largely through the Russian Ministry of Atomic Energy.

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Correspondence to A. V. Yeremin.

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Oganessian, Y., Yeremin, A., Popeko, A. et al. Synthesis of nuclei of the superheavy element 114 in reactions induced by 48Ca. Nature 400, 242–245 (1999). https://doi.org/10.1038/22281

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