Fission product yield measurements using monoenergetic photon beams

¹ Department of Physics, Duke University, Durham, NC 27708, USA
² Triangle Universities Nuclear Laboratory, Durham NC 27708, USA
³ Nuclear and Chemical Sciences Division, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA

^a e-mail: krishi@tunl.duke.edu; krishichayan@gmail.com

Published online: 13 September 2017

Abstract

Measurements of fission products yields (FPYs) are an important source of information on the fission process. During the past couple of years, a TUNL-LANL-LLNL collaboration has provided data on the FPYs from quasi monoenergetic neutron-induced fission on ²³⁵U, ²³⁸U, and ²³⁹Pu and has revealed an unexpected energy dependence of both asymmetric fission fragments at energies below 4 MeV. This peculiar FPY energy dependence was more pronounced in neutron-induced fission of ²³⁹Pu. In an effort to understand and compare the effect of the incoming probe on the FPY distribution, we have carried out monoenergetic photon-induced fission experiments on the same ²³⁵U, ²³⁸U, and ²³⁹Pu targets. Monoenergetic photon beams of E_γ = 13.0 MeV were provided by the HIγS facility, the world's most intense γ-ray source. In order to determine the total number of fission events, a dual-fission chamber was used during the irradiation. These irradiated samples were counted at the TUNL's low-background γ-ray counting facility using high efficient HPGe detectors over a period of 10 weeks. Here we report on our first ever photofission product yield measurements obtained with monoenegetic photon beams. These results are compared with neutron-induced FPY data.