New Short-Lived Fission Product Yield Experiment at Oregon State University

A new experimental setup at the Oregon State University (OSU) TRIGA reaction is being designed, with the goal of measuring short-lived fission product yields and investigating discrepancies in fission product γ-ray branching ratios. ²³⁸U cumulative fast fission product yields were recently measured using Godiva-IV. The fission product yields were extracted by analyzing fission product γ-rays which rely on γ-ray branching ratios. This method relies on the accuracy of γ-ray branching ratios, some of which may not be reliable. Measurements at Godiva-IV are limited to begin ~1 hour post-irradiation. The OSU rabbit system allows the rapid transport of samples from the core to the counting setup within 3 seconds. The new setup will consist of four Compton-suppressed HPGe clover detectors providing high efficiency for γ-ray detection, and the high segmentation of the array will increase the γ- γ coincidence detection efficiency and enable the investigation of gamma-ray branching ratios. Results from a preliminary proof-of-principle measurement at the OSU TRIGA reactor will be presented along with the current status of preparations for the future campaign.

This work was funded by the Office of Defense Nuclear Nonproliferation Research and Development within the U.S. DOE - NNSA. This work was performed under the auspices of the U.S. DOE by LLNL under Contract DE-AC52-07NA27344.