Published in Physical Review C 84 034613 (2011)
LA-UR-11-11011

Fission-fragment mass distributions from strongly damped shape evolution

Jørgen Randrup
Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA

Peter Möller
Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA

Arnold J. Sierk
Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA

Random walks on five-dimensional potential-energy surfaces were recently found to yield fission-fragment mass distributions that are in remarkable agreement with experimental data. Within the framework of the Smoluchowski equation of motion, which is appropriate for highly dissipative evolutions, we discuss the physical justification for that treatment and investigate the sensitivity of the resulting mass yields to a variety of model ingredients, including in particular the dimensionality and discretization of the shape space and the structure of the dissipation tensor. The mass yields are found to be relatively robust, suggesting that the simple random walk presents a useful calculational tool. Quantitatively refined results can be obtained by including physically plausible forms of the dissipation, which amounts to simulating the Brownian shape motion in an anisotropic medium The complete manuscript in color as a .pdf file is available for download.

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Created: Feb23 2012 --> Last modified: Thu July 5 2012