Preliminary results on the U-233 α-ratio measurement at n_TOF

Abstract

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.