Abstract
In the framework of nuclear waste incineration and design of new generation nuclear reactors, experimental data on fission probabilities and on fission fragment yields of minor actinides are crucial to design prototypes. Transfer-induced fission has proven to be an efficient method to study fission probabilities of actinides which cannot be investigated with standard techniques due to their high radioactivity. We report on the preliminary results of an experiment performed at GANIL that investigates fission probabilities with multi-nucleon transfer reactions in inverse kinematics between a 238U beam on a 12C target. Actinides from U to Cm were produced with an excitation energy range from 0 to 30 MeV. In addition, inverse kinematics allowed to characterize the fission fragments in mass and charge. A key point of the analysis resides in the identification of the actinides produced in the different transfer channels. The new annular telescope SPIDER was used to tag the target-like recoil nucleus of the transfer reaction and to determine the excitation energy of the actinide. The fission probability for each transfer channel is accessible and the preliminary results for 238U are promising.
Highlights
Minor actinides are currently produced in the U-Pu electronuclear fuel cycle
We report on the preliminary results of an experiment performed at GANIL that investigates fission probabilities with multi-nucleon transfer reactions in inverse kinematics between a 238U beam on a 12C target
The actinides produced by transfer reactions are tagged by the detection and the identification of the target-like recoil nuclei in SPIDER. ∆E-Eres correlations are presented in Fig. 3 with the identification of C, B, Be, Li and He
Summary
Minor actinides are currently produced in the U-Pu electronuclear fuel cycle. Due to their high radioactivity and their low fissibility, they involve risks and are considered as ultimate wastes. Instead of deep geological repository, two other options are worthwhile investigating : the reduction of their production in new fuels cycles (e.g. based on Th-U) and their incineration by transmutation in sub-critical reactors In both cases, data such as fission cross sections or isotopic distribution of the fission fragments are required to design dedicated facilities. In the Weisskopf-Ewing limit of the statistical Hauser-Feshbach theory, the fission probabilities are independent of the angular momentum and parity of the compound nucleus and must be thereby the same for neutron capture and transfer reaction. The validity of this approximation the surrogate method required is subject of debate [2]. The inverse kinematics leads to a forward focusing of the fission fragments with a high velocity, which improves the detection efficiency and allows a better resolution for their identification
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