Journal Article Role of multichance fission in the description of fission-fragment mass distributions at high energies

Hirose, K.  ,  Nishio, K.  ,  Tanaka, S.  ,  Leguillon, R.  ,  Makii, H.  ,  Nishinaka, Ichiro  ,  Orlandi, R.  ,  Tsukada, K.  ,  Smallcombe, J.  ,  J. Vermeulen, M.  ,  Chiba, S.  ,  Aritomo, Y.  ,  Ohtsuki, T.  ,  Nakano, K.  ,  Araki, S.  ,  Watanabe, Y.  ,  Tatsuzawa, R.  ,  Takai, N.  ,  Yamura, N.  ,  Goto, S.  ,  Tsekhanovich, I.  ,  N. Andreyev, A.

119 ( 22 )  , pp.222501-1 - 222501-6 , 2017-12 , Amwrican Physical Society
Fission-fragment mass distributions were measured for 237–240U, 239–242Np, and 241–244Pu populated in the excitation-energy range from 10 to 60 MeV by multinucleon transfer channels in the reaction 18O+238U at the Japan Atomic Energy Agency tandem facility. Among them, the data for 240U and 240,241,242Np were observed for the first time. It was found that the mass distributions for all the studied nuclides maintain a double-humped shape up to the highest measured energy in contrast to expectations of predominantlysymmetric fission due to the washing out of nuclear shell effects. From a comparison with the dynamical calculation based on the fluctuation-dissipation model, this behavior of the mass distributions was unambiguously attributed to the effect of multichance fission.

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