Dissipative effects in fission investigated with proton-on-lead reactions
1 Universidad de Santiago de Compostela, E-15782 Santiago de Compostela, Spain
2 CEA, DAM, DIF, F-91297 Arpajon France
3 Institut de Physique Nucléaire d’Orsay, F-91406 Orsay France
4 Universidad de Vigo, E-36200 Vigo, Spain
5 Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
6 GSI Helmholtzzentrum für Schwerionenforschung GmbH, D-64291 Darmstadt, Germany
7 Grand Accélérateur National d’Ions Lourds, F-14076 Caen Cedex 5, France
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Published online: 11 May 2016
The complete kinematic measurement of the two fission fragments permitted us to investigate dissipative effects at large deformations, between the saddle-point and the corresponding scission configurations. Up to now, this kind of study has only been performed with fusionfission reactions using a limited number of observables, such as the mass distribution of the fission fragments or the neutron multiplicities. However, the large angular momenta gained by the compound nucleus could affect the conclusions drawn from such experiments. In this work, the use of spallation reactions, where the fissioning systems are produced with low angular momentum, small deformations and high excitation energies, favors the study of dissipation, and allowed us to define new observables, such as postscission neutron multiplicities and the neutron excess of the final fission fragments as a function of the atomic number of the fissioning system. These new observables are used to investigate the dissipation at large deformations.
© Owned by the authors, published by EDP Sciences - SIF, 2016
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