Short-lived fission products from 235U using monoenergetic neutrons

Fission product yields (FPYs) are among the fundamental fission observables that play crucial roles in basic and applied nuclear physics. Accurate knowledge of the FPYs is necessary for addressing questions relevant to nucleosynthesis in the cosmos, resolving the reactor antineutrino anomaly, decay heat release in nuclear reactors, and national security applications. In this talk, I will discuss an ongoing campaign by the LLNL-LANL-TUNL collaboration to measure the cumulative FPYs from neutron-induced fission of ^235,238U and ²³⁹Pu at the Triangle Universities Nuclear Laboratory (TUNL). Emphasis will be given on our recent experimental effort utilizing the RApid Belt-driven Irradiated Target Transfer System (RABITTS) to measure short-lived (T_1/2 ~ minutes to seconds) fission products extending our previous long-lived (T_1/2 > 1 hour) FPY measurements[1]. An overview of the experimental methods with the RABITTS and some preliminary data for the ²³⁵U(n,f) reaction at En=4.6 MeV will be presented.

This work was performed under the auspices of the U.S. DOE by LLNL under contract DE-AC52-07NA27344.

[1] M.E. Gooden et al., "Energy Dependence of Fission Product Yields from 235U, 238U, and 239Pu for Incident Neutron Energies Between 0.5 and 14.8 MeV." Nuclear Data Sheets 131, 319 (2016).