https://doi.org/10.1140/epja/i2006-10091-y
Nuclear Structure and Reactions
Measurement of evaporation residue cross-sections of the reaction 30Si + 238U at subbarrier energies
1
Gesellschaft für Schwerionenforschung mbH, D-64220, Darmstadt, Germany
2
Japan Atomic Energy Agency, 319-1195, Tokai, Ibaraki, Japan
3
Institut für Kernphysik, Johann Wolfgang Goethe-Universität, D-60486, Frankfurt am Main, Germany
4
Department of Nuclear Physics, Comenius University, SK-84215, Bratislava, Slovakia
5
Higher Institue of Technologies and Applied Sciences, 10400, Habana, Cuba
6
Institute of Modern Physics, Chinese Academy of Sciences, 730000, Lanzhou, PRC
7
St. Petersburg State University, 198504, Stari Petergof, St. Petersburg, Russia
8
CUPP, University of Oulu, FIN-86801, Pyhäjärvi, Finland
9
Laboratory of Nuclear Science, Tohoku University, 982-0826, Sendai, Japan
10
Flerov Laboratory of Nuclear Reactions, JINR, 141 980, Dubna, Russia
11
Institut für Kernchemie, Johannes Gutenberg-Universität Mainz, D-55099, Mainz, Germany
* e-mail: nishio.katsuhisa@jaea.go.jp
Received:
12
July
2006
Accepted:
28
August
2006
Published online:
14
September
2006
The reaction 30Si + 238U → 268Sg* was studied at beam energies close to the Coulomb barrier. At a center-of-mass energy of E c.m. = 144.0MeV for reactions at half thickness of the target we measured three decay chains of 263Sg produced by evaporation of five neutrons. The cross-section was ( 67+67 -37) pb. At E c.m. = 133.0MeV we measured three spontaneously fissioning nuclei which we assigned to the isotope 264Sg. The production cross-section was ( 10+10 -6) pb and a half-life of ( 120+126 -44) ms was determined. This half-life is a factor of twenty shorter than theoretical predictions. At E c.m. = 128.0MeV an upper cross-section limit of 15pb was measured. The cross-section data reveal a strong influence of the orientation of the deformed target nucleus on the production yield. Compared to excitation functions measured for the lighter system 16O + 238U → 254Fm*, a reduction of the fusion probability was observed at low beam energies indicating increasing competition from quasifission processes.
PACS: 25.60.Pj Fusion reactions – / 23.60.+e α decay – / 25.85.Ca Spontaneous fission – / 27.90.+b 220 ⩽ A –
© Società Italiana di Fisica and Springer-Verlag, 2006