Nuclear Science and Techniques

《核技术》(英文版) ISSN 1001-8042 CN 31-1559/TL     2019 Impact factor 1.556

Nuclear Science and Techniques ›› 1997, Vol. 8 ›› Issue (1): 1

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Systematic study of anomalous fragment anisotropies in subbarrier complete fusion-fission reactions

Zhang Huan-Qiao, Liu Zu-Hua, Xu Jin-Cheng, Qian Xing, Qiao Yu and Lin Cheng-Jian   

  1. China Institute of Atomic Energy, Beijing 102413
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Zhang Huan-Qiao, Liu Zu-Hua, Xu Jin-Cheng, Qian Xing, Qiao Yu and Lin Cheng-Jian. Systematic study of anomalous fragment anisotropies in subbarrier complete fusion-fission reactions.Nuclear Science and Techniques, 1997, 8(1): 1

Abstract: The complete fusion-fission is separated from the transfer-induced-fission with the fragment folding angle technique. The cross sections and fragment angular distributions for the complete fusion-fission reactions of 11B +238U(237Np), 12C +237Np, 16O + 232Th(238U) and 19F + 232Th at near- and sub-barrier energies have been measured. The present fusion and fission standard models can reproduce both the excitation functions and the fragment anisotropies for the systems of 11B +238U(237Np) and 12C+237Np; but fail to explain both the experimental data for the other 3 systems simultaneously. The evidence of the entrance-channel dependence of fission-fragment anisotropies is revealed by comparison of the 11B+237Np and 16O+232Th data. Based on the observations, a new version model of preequilibrium fission is put forward to explain the anomaly.

Key words: Complete fusion-fission reactions, Fragiment anisotropies, Entrance-channel dependence, Transfer-induced fission, Preequilibrium fission