Measurements of cross sections for the fusion-evaporation reactions 204,206,207,208Pb+48Ca and 207Pb+34S: Decay properties of the even-even nuclides 238Cf and 250No

Yu. Ts. Oganessian, V. K. Utyonkov, Yu. V. Lobanov, F. Sh. Abdullin, A. N. Polyakov, I. V. Shirokovsky, Yu. S. Tsyganov, A. N. Mezentsev, S. Iliev, V. G. Subbotin, A. M. Sukhov, K. Subotic, O. V. Ivanov, A. N. Voinov, V. I. Zagrebaev, K. J. Moody, J. F. Wild, N. J. Stoyer, M. A. Stoyer, and R. W. Lougheed
Phys. Rev. C 64, 054606 – Published 10 October 2001
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Abstract

In preparation for recent experiments on the synthesis of superheavy nuclei with Z=114 in the reaction 244Pu+48Ca, we modified the Dubna gas-filled recoil separator and its detection system and carried out bombardments of lead targets with 48Ca projectiles. We studied excitation functions of the reactions 206Pb(48Ca,14n) and 204,207,208Pb(48Ca,2n). Maximum cross sections for the evaporation of 1–4 neutrons in the complete fusion reaction 206Pb+48Ca were measured to be σ1n=60nb, σ2n=500nb, σ3n=30nb, and σ4n=0.3nb. In the bombardment of an enriched 204Pb target, we simultaneously obtained excitation functions of the 204,206,207,208Pb(48Ca,2n) reactions induced on the isotopic admixtures present in the target material. The maximum cross sections for the evaporation of two neutrons from the compound nuclei 256No, 255No, and 252No were measured to be 2.1 μb, 1.3 μb, and 10 nb, respectively. The spontaneously fissioning even-even isotope 250No, with a half-life T1/2=36μs, was identified for the first time in this experiment. In the reaction 207Pb+34S, we measured the excitation function for the production of the 21-ms spontaneously fissioning isotope 238Cf, confirming our preliminary identification of this nuclide based on the results of cross bombardments.

  • Received 27 April 2001

DOI:https://doi.org/10.1103/PhysRevC.64.054606

©2001 American Physical Society

Authors & Affiliations

Yu. Ts. Oganessian, V. K. Utyonkov, Yu. V. Lobanov, F. Sh. Abdullin, A. N. Polyakov, I. V. Shirokovsky, Yu. S. Tsyganov, A. N. Mezentsev, S. Iliev, V. G. Subbotin, A. M. Sukhov, K. Subotic, O. V. Ivanov, A. N. Voinov, and V. I. Zagrebaev

  • Joint Institute for Nuclear Research, 141980 Dubna, Russia

K. J. Moody, J. F. Wild, N. J. Stoyer, M. A. Stoyer, and R. W. Lougheed

  • University of California, Lawrence Livermore National Laboratory, Livermore, California 94551

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Vol. 64, Iss. 5 — November 2001

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