Measurements of short-lived fission product yields using monoenergetic neutron and photon beams

¹ Duke University, Durham, NC 27708
² Triangle Universities Nuclear Laboratory, Durham, NC 27708
³ Lawrence Livermore National Laboratory, Livermore, CA 94550
⁴ Los Alamos National Laboratory, Los Alamos, NM 87544
⁵ Colorado School of Mines, Golden, CO 80401
⁶ North Carolina State University, Raleigh, NC 27695

^* e-mail: sfinch@tunl.duke.edu

Published online: 28 September 2020

Abstract

A joint TUNL-LLNL-LANL collaboration was formed to measure the absolute fission product yields from the ²³⁵ U, ²³⁸ U, and ²³⁹ Pu isotopes. Our goal is to study the energy evolution of fission products using monoenergetic beams. In order to extend our successful fission product-yield studies to include products with shorter half-lives, a RApid Belt-driven Irradiated Target Transfer System, named RABITTS, was constructed. This system allows us to perform cyclic activation and quantify fission products with γ-ray spectroscopy using HPGe detectors. Both a 1 meter and 10 meter transfer system have been developed, with transit times of 0.4 and 1.1 seconds, respectively. Using these systems, we have measured sub-second half-lives. Our goal is to measure fission product yields from neutron-induced fission with E_n = 0.5 − 14.8 MeV and photofission with E_γ = 8 − 15 MeV. A detailed characterization of the system’s performance is presented, including preliminary fission product measurements, and the expected sensitivity.