Preliminary Results On The U-233 Alpha-Ratio Measurement At N_tof

U-233 is the fissile nuclei in the Th-U fuel cycle with a particularily small neutron capture cross setion which is on average about one order of magnitude lower than its fission cross section. Hence, the measurement of the U-233(n,gamma) cross section relies on a method to accurately distinguish between capture and fission gamma-rays. A measurement of the U-233 alpha-ratio has been performed at the n_TOF facility at CERN using a so-called fission tagging setup, coupling nTOF 's Total Absorption Calorimeter with a novel fission chamber to tag the fission gamma-rays. The experimental setup is described and essential parts of the analysis are discussed. Finally, a preliminary U-233 alpha-ratio is presented.