Eur. Phys. J. A (2017) 53: 7
https://doi.org/10.1140/epja/i2017-12188-6

Regular Article - Theoretical Physics

Evolution of uranium fission-fragment charge yields with neutron number

Strong effect of multi-chance fission on yield asymmetries

¹ Theoretical Division, Los Alamos National Laboratory, 87545, Los Alamos, NM, USA
² Grand Accélérateur National d’Ions Lourds, CEA/DSM-CNRS/IN2P3, 14076, Caen, France

^* e-mail: moller@lanl.gov

Received: 22 September 2016
Accepted: 11 December 2016
Published online: 18 January 2017

Abstract

We use the Brownian shape-motion model, with its recent extensions, which allow modeling of odd-even staggering, to calculate the evolution of fission-fragment charge distributions with neutron number for the compound-system sequence ²³⁴U, ²³⁶U, ²³⁸U, and ²⁴⁰U. We compare to experimental data where available, for neutron- and electromagnetic-induced fission over a compound-nucleus excitation energy range from about 6 to 20 MeV. A notable result of the study is that the evolution of the location of the peak charge yield from in ²³⁴U towards in heavier isotopes, seen in the experimental data, is present also in the calculated yields. We further show that to describe yields at higher compound-nucleus excitation energies, then, already at 20 MeV, it is necessary to take multi-chance fission into account.