Experimental study of resonance interference between Th-232 and U-233

A preliminary result is reported for an experiment of the effective U-233 neutron cross section in its unresolved energy region shielded with the resonance structure of Th-232 in reactors. The experiment is an extension of the transmission and self-indication measurement which can determine the self-shielded cross section of a reactor material. In the present experiment, neutrons transmitted through thorium samples of several thicknesses are detected with the B-10 (n, gamma) and U-233 (n, absorption) reactions. The former is the transmission measurement and the latter may be called a mutual-indication measurement. Considerable improvements in the experimental technique are still needed to escape from the intense gamma-ray background come from the U-233 indication sample. (author)