Exploratory study of fission product yield determination from photofission of Pu239 at 11 MeV with monoenergetic photons

Here, measurements of fission product yields play an important role for the understanding of fundamental aspects of the fission process. Recently, neutron-induced fission product-yield data of ²³⁹Pu at energies below 4 MeV revealed an unexpected energy dependence of certain fission fragments. In order to investigate whether this observation is prerogative to neutron-induced fission, a program has been initiated to measure fission product yields in photoinduced fission. Here we report on the first ever photofission product yield measurement with monoenergetic photons produced by Compton back-scattering of FEL photons. The experiment was performed at the High-Intensity Gamma-ray Source at Triangle Universities Nuclear Laboratory on ²³⁹Pu at E_γ = 11 MeV. In this exploratory study the yield of eight fission products ranging from ⁹¹Sr to ¹⁴³Ce has been obtained.