1994 Fiscal Year Final Research Report Summary

MULTI-MODE FISSION OF ACTINIDES INDUCED BY THERMAL NEUTRON

Research Project

Project/Area Number	05640629
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	Inorganic chemistry
Research Institution	Osaka University
Principal Investigator	BABA Hiroshi Osaka University, Science Professor, 理学部, 教授 (60156536)
Co-Investigator(Kenkyū-buntansha)	NAKAGOME Yoshihiro Kyoto University, The Research Reactor Institute Assistant Professor, 原子炉実験所, 助教授 (50027455) YOKOYAMA Akihiko Osaka University, Science Research Assistant, 理学部, 助手 (80230655) TAKAHASHI Naruto Osaka University, Science Research Assistant, 理学部, 助手 (00197162) SAITO Tadashi Osaka University, Science Assistant Professor, 理学部, 助教授 (50153812)
Project Period (FY)	1993 – 1994
Keywords	Actinides / Fission / Thermal Neutron / Time-of-Flight / Kinetic Energy / Mass / Prompt Neutron
Research Abstract	Though the many investigations about the fission mechanisms of uranium and plutonium isotopes induced by thermal neutrons have been done, there are many problems undissolved in the fission. Recently, the existence of two-mode fission process was confirmed in the experiment of pre-actinide and heavy-actinide nuclides fission. Further, theoretical approaches can explain to a certain extent the fission mechanisms of actinides. We have developed the time-of-flight instrument in order to measure precise mass distribution of actinide fission. The time-of-flight consists of thin film scintilators as the start counter and silicon surface barrier detectors as the stop counter. First, we measured the velocities and the kinetic energies of the spontaneous fission fragments from ^<252>Cf and then the functions of this instrument were checked. The obtained multiplicities of the promptneutrons from the fission fragments were well agreed with the values obtained by Wahl. Further, we measured the velocities and the kinetic energies of the fission fragments in the ^<235>U+n_<th> system at The Reserch Reactor Institure, Kyoto University and obtained the kinetic energy and the mass distributions. We could not observe the existence of the multi-mode fission.