U-233 is of key importance among the fissile nuclei in the Th-U fuel cycle. A particularity of U-233 is its small neutron capture cross-section, which is on average about one order of magnitude lower than the fission cross-section. The accuracy in the measurement of the U-233 capture crosssection depends crucially on an efficient capture-fission discrimination, thus a combined set-up of fission and y-detectors is needed. A measurement of the U-233 capture cross-section and capture-to -fission ratio was performed at the CERN n_TOF facility. The Total Absorption Calorimeter (TAC) of n_TOF was employed as y-detector coupled with a novel compact ionization chamber as fission detector. A brief description of the experimental set-up will be given, and essential parts of the analysis procedure as well as the preliminary response of the set-up to capture are presented and discussed.
