Eur. Phys. J. A (2012) 48: 62
https://doi.org/10.1140/epja/i2012-12062-1

Regular Article - Experimental Physics

The reaction ⁴⁸Ca + ²⁴⁸Cm → ²⁹⁶116^* studied at the GSI-SHIP

¹ GSI Helmholtzzentrum für Schwerionenforschung, 64291, Darmstadt, Germany
² Institut für Physik, Goethe-Universität Frankfurt, 60438, Frankfurt, Germany
³ Helmholtz-Institut Mainz, Johannes Gutenberg-Universität, 55099, Mainz, Germany
⁴ Department of Nuclear Physics and Biophysics, Comenius University, 84248, Bratislava, Slovakia
⁵ Johannes Gutenberg-Universität Mainz, 55128, Mainz, Germany
⁶ Lawrence Livermore National Laboratory, 94551, Livermore, CA, USA
⁷ Department of Physics, University of Jyväskylä, 40351, Jyväskylä, Finland
⁸ Japan Atomic Energy Agency, 319-1195, Tokai, Ibaraki, Japan
⁹ Joint Institute for Nuclear Research, 141980, Dubna, Russian Federation

^* e-mail: S.Hofmann@gsi.de

Received: 16 January 2012
Revised: 9 March 2012
Accepted: 22 March 2012
Published online: 3 May 2012

Abstract

The synthesis of element 116 in fusion-evaporation reactions of a ⁴⁸Ca beam with radioactive ²⁴⁸Cm targets was studied at the velocity filter SHIP of GSI in Darmstadt. At excitation energies of the compound nuclei of 40.9MeV, four decay chains were measured, which were assigned to the isotope ²⁹²116, and one chain, which was assigned to ²⁹³116. Measured cross-sections of (3.4 _−1.6 ^+2.7 ) pb and (0.9 _−0.7 ^+2.1 ), respectively, and decay data of the chains agree with data measured previously at the Flerov Laboratory of Nuclear Reactions in Dubna. As a new result, one α-decay chain was measured, which terminates after four α decays by spontaneous fission. The α energies of the second-to-fourth decay are considerably higher than those measured for the α decays of ²⁸⁹114, ²⁸⁵Cn, and ²⁸¹Ds and the spontaneous fission half-life is significantly longer than that of ²⁷⁷Hs measured in previous experiments. A possible assignment is discussed in the frame of excited quasiparticle states of nuclei populated in the decay chain from ²⁹³116. Also other possible assignments were considered and are discussed. At an excitation energy of 45.0MeV no events were observed resulting in a one-event cross-section limit of 1.6 pb. The technical aspects related with the use of radioactive target material at SHIP are described in detail. The experience gained in this experiment will serve as a basis for future experiments aiming to study still heavier elements at the velocity filter SHIP.