Fission fragments mass distributions of nuclei populated by the multinucleon transfer channels of the 18O +232Th reaction

R Léguillon,R Orlandi,K Nishio,I Nishinaka,N Takaki,R Tatsuzawa,K Tsukada,N Tamura,A.N Andreyev,Y Aritomo,S Goto,I Tsekhanovich,S Chiba,K Hirose,H Makii,J Smallcombe,T Ohtsuki,C.M Petrache

doi:10.1016/j.physletb.2016.08.010

Abstract

Abstract It is shown that the multinucleon transfer reactions is a powerful tool to study fission of exotic neutron-rich actinide nuclei, which cannot be accessed by particle-capture or heavy-ion fusion reactions. In this work, multinucleon transfer channels of the 18O + 232Th reaction are used to study fission of fourteen nuclei 231,232,233,234Th, 232,233,234,235,236Pa, and 234,235,236,237,238U. Identification of fissioning nuclei and of their excitation energy is performed on an event-by-event basis, through the measurement of outgoing ejectile particle in coincidence with fission fragments. Fission fragment mass distributions are measured for each transfer channel, in selected bins of excitation energy. In particular, the mass distributions of 231,234Th and 234,235,236Pa are measured for the first time. Predominantly asymmetric fission is observed at low excitation energies for all studied cases, with a gradual increase of the symmetric mode towards higher excitation energy. The experimental distributions are found to be in general agreement with predictions of the fluctuation–dissipation model.

Highlights

IntroductionInduced nuclear fission is a unique decay process which may be described by the interplay of macroscopic (collective) and microscopic (single particle) degrees of freedom in a nucleus [1]
Induced nuclear fission is a unique decay process which may be described by the interplay of macroscopic and microscopic degrees of freedom in a nucleus [1]
The scope of the present work is to explore the potential of the multinucleon transfer (MNT) reactions to measure FFMDs and their excitation energy dependence for the neutron-rich nuclei, which cannot be accessed by particle-capture and/or heavy-ion fusion reactions

Summary

Introduction

Induced nuclear fission is a unique decay process which may be described by the interplay of macroscopic (collective) and microscopic (single particle) degrees of freedom in a nucleus [1]. Such a description of the fission process allows for studies of nuclear shell structures, nuclear viscosity and their excitation energy dependence at extreme values of deformation. (3 He,pf) or (6 Li,df) and similar types started to be exploited. Often, such studies concentrated mostly on the measurements of fission probabilities and their excitation energy dependence, see e.g. Often, such studies concentrated mostly on the measurements of fission probabilities and their excitation energy dependence, see e.g. [6,7,8,9,10,11,12,13] and a review of experiments on the so-called ‘surrogate’

Methods

Results

Conclusion