Experiments on the synthesis of superheavy nuclei Fl284 and Fl285 in the Pu239,240+Ca48 reactions

V. K. Utyonkov, N. T. Brewer, Yu. Ts. Oganessian, K. P. Rykaczewski, F. Sh. Abdullin, S. N. Dmitriev, R. K. Grzywacz, M. G. Itkis, K. Miernik, A. N. Polyakov, J. B. Roberto, R. N. Sagaidak, I. V. Shirokovsky, M. V. Shumeiko, Yu. S. Tsyganov, A. A. Voinov, V. G. Subbotin, A. M. Sukhov, A. V. Sabel'nikov, G. K. Vostokin, J. H. Hamilton, M. A. Stoyer, and S. Y. Strauss
Phys. Rev. C 92, 034609 – Published 15 September 2015

Abstract

Irradiations of Pu239 and Pu240 targets with Ca48 beams aimed at the synthesis of Z=114 flerovium isotopes were performed at the Dubna Gas Filled Recoil Separator. A new spontaneously fissioning (SF) isotope Fl284 was produced for the first time in the Pu240+Ca48 (250 MeV) and Pu239+Ca48 (245 MeV) reactions. The cross section of the Pu239(Ca48,3n)Fl284 reaction channel was about 20 times lower than predicted by theoretical models and about 50 times lower than the maximum fusion-evaporation cross section for the 3n and 4n channels measured in the Pu244+Ca48 reaction. In the Pu240+Ca48 experiment, performed at 245 MeV in order to maximize the 3n-evaporation channel, three decay chains of Fl285 were detected. The α-decay energy of Fl285 was measured for the first time and decay properties of its descendants Cn281, Ds277, Hs273, Sg269, and Rf265 were determined with higher accuracy. The assignment of SF events observed during the irradiation of the Pu240 target with a 250 MeV Ca48 beam to Fl284 decay is presented and discussed. The cross sections at both Ca48 energies are similar and exceed that observed in the reaction with the lighter isotope Pu239 by a factor of 10. The decay properties of the synthesized nuclei and their production cross sections indicate a rapid decrease of stability of superheavy nuclei as the neutron number decreases from the predicted magic neutron number N=184.

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  • Received 22 July 2015

DOI:https://doi.org/10.1103/PhysRevC.92.034609

©2015 American Physical Society

Authors & Affiliations

V. K. Utyonkov1,*, N. T. Brewer2, Yu. Ts. Oganessian1, K. P. Rykaczewski2, F. Sh. Abdullin1, S. N. Dmitriev1, R. K. Grzywacz2,3, M. G. Itkis1, K. Miernik2,4, A. N. Polyakov1, J. B. Roberto5, R. N. Sagaidak1, I. V. Shirokovsky1, M. V. Shumeiko1, Yu. S. Tsyganov1, A. A. Voinov1, V. G. Subbotin1, A. M. Sukhov1, A. V. Sabel'nikov1, G. K. Vostokin1, J. H. Hamilton6, M. A. Stoyer7, and S. Y. Strauss8

  • 1Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, RU-141980 Dubna, Russian Federation
  • 2Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
  • 3Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
  • 4Faculty of Physics, University of Warsaw, PL-02-093 Warsaw, Poland
  • 5Science and Technology Partnerships Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
  • 6Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235, USA
  • 7Nuclear and Chemical Sciences Division, Lawrence Livermore National Laboratory, Livermore, California 94551, USA
  • 8Department of Physics, University of Notre Dame, Notre Dame, Indiana 46566, USA

  • *utyonkov@sungns.jinr.ru

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Vol. 92, Iss. 3 — September 2015

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