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 Libration, 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, United Kingdom

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

Published online: 22 November 2017

Abstract

It is shown that multi-nucleon transfer reaction is a powerful tool to study fission of exotic neutronrich actinide nuclei, which cannot be accessed by particle-capture or heavy-ion fusion reactions. In this work, multi-nucleon transfer channels of the reactions of ¹⁸O+²³²Th, ¹⁸O+²³⁸U, ¹⁸O+²⁴⁸Cm, and ¹⁸O+²³⁷Np were used to measure fission-fragment mass distribution for each transfer channel. 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 is shown that mass-asymmetric structure remaining at high excitation energies originates from low-excited and less neutronrich excited nuclei due to higher-order chance fissions.