Systematic Studies of Fission Product-Yield Distributions from Neutron Induced Fission

The distribution of fragment masses following fission is one of the most basic quantities that has been observed since the discovery of fission by Hahn and Strassmann in 1938, and these fission product yields (FPYs) are an important source of information that are used for basic and applied physics. We are performing a self-consistent, high-precision, and time-dependent FPY data for 235U, 238U, and 239Pu isotopes using monoenergetic and pulsed neutron beams for incident energies from 0.5 to 15.0 MeV. Using irradiations of varying duration, the energy dependence of the cumulative and independent yields have been measured for more than two dozen fission products, with half-lives ranging from minutes to months, on these targets. This work aims to provide a unique capability for self-consistent measurement of a much broader range of FPY data relevant to many applications. We will discuss the uniqueness of these FPY data thus will provide insights crucial for the development of fission theory as well as important benchmarks for new data evaluations based on high-precision differential fission products.

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344.