A Method to Calculate Fission-Fragment Yields Y(Z,N) versus Proton and Neutron Number in the Brownian Shape-Motion Model
Application to calculations of U and Pu charge yields

P. MÖLLER
Theoretical Division, Los Alamos National Laboratory, New Mexico 87545, USA

T. ICHIKAWA
Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502, Japan

European Physics Journal A 51 (2015) 173
Los Alamos National Laboratory Preprint No LA-UR-15-26634.


Abstract:

We propose a method to calculate the two-dimensional (2D) fission-fragment yield Y(Z,N) versus both proton and neutron number, with inclusion of odd-even staggering effects in both variables. The approach is to use Brownian shape-motion on a macroscopic-microscopic potential-energy surface which, for a particular compound system is calculated versus four shape variables: elongation (quadrupole moment Q2), neck diameter d, left nascent fragment spheroidal deformation εf1, right nascent fragment deformation εf2 and two asymmetry variables, namely proton and neutron numbers in each of the two fragments. The extension of previous models 1) introduces a method to calculate this generalized potential-energy function and 2) allows the correlated transfer of nucleon pairs in one step, in addition to sequential transfer. In the previous version the potential energy was calculated as a function of Z and N of the compound system and its shape, including the asymmetry of the shape. We outline here how to generalize the model from the "compound-system" model to a model where the emerging fragment proton and neutron numbers also enter, over and above the compound system composition.

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Figure Fig-01-moller-epja.eps.gz in format .eps.gz and Fig-01-moller-epja.pdf in .pdf format is available for download.
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Figure Fig-08-moller-epja.eps.gz in format .eps.gz and Fig-08-moller-epja.pdf in .pdf format is available for download.
Figure Fig-09-moller-epja.eps.gz in format .eps.gz and Fig-09-moller-epja.pdf in .pdf format is available for download.
Peter Moller
Created: August 24 2014 --> Last modified: August 24 2015