Nucleation and cluster formation in low-density nucleonic matter: A   mechanism for ternary fission
  Ternary fission yields in the reaction 241Pu(nth,f) are calculated using a new model which assumes a nucleation-time moderated chemical equilibrium in the low density matter which constitutes the neck region of the scissioning system. The temperature, density, proton fraction and fission time required to fit the experimental data are derived and discussed. A reasonably good fit to the experimental data is obtained. This model provides a natural explanation for the observed yields of heavier isotopes relative to those of the lighter isotopes, the observation of low proton yields relative to 2H and 3H yields and the non-observation of 3He, all features which are shared by similar thermal neutron induced and spontaneous fissioning systems. 
S. Wuenschel, H. Zheng, K. Hagel, B. Meyer, M. Barbui, E.J. Kim, G.   Roepke and J. B. Natowitz
nucl-ex nucl-th