Study of fission using multi-nucleon transfer reactions

¹ Advanced Science Research Center, Japan Atomic Energy Agency, 2-4 Shirakata, Tokai, Naka-gun, Ibaraki 319-1195, Japan
² Laboratory for Advanced Nuclear Energy, Tokyo Institute of Technology, 2-12-1, Ookayama, Meguro-ku, Tokyo 152-8550, Japan
³ Faculty of Science and Engineering, Kindai University, Higashi-Osaka 577-8502, Japan
⁴ Research Reactor Institute, Kyoto University, Kumatori-cho, Sennangun, Osaka 590-0494, Japan
⁵ University of Bordeaux, 351 Cours de la Libération, 33405 Talence Cedex, France
⁶ Centre des Sciences Nucléaire et des Sciences de la Matière, Université Paris-Saclay, CNRS/IN2P3, 91406 Orsay, France
⁷ Department of Physics, University of York, Heslington, York, YO10 5DD, UK

^* e-mail: nishio.katsuhisa@jaea.go.jp

Published online: 6 March 2018

Abstract

Multi-nucleon transfer channels of the reactions of ¹⁸O+²³²Th, ¹⁸O+²³⁸U, ¹⁸O+²⁴⁸Cm were used to measure fission-fragment mass distribution for various nuclides and their excitation energy dependence. Predominantly asymmetric fission is observed at low excitation energies for all the studied cases, with an increase of the symmetric fission towards high excitation energies. Experimental data are compared with predictions of the fluctuation-dissipation model, where effects of multi-chance fission (neutron evaporation prior to fission) was introduced. It was shown that a reliable understanding of the observed fission fragment mass distributions can be obtained only invoking multi-chance fissions.