STUDY ON NEUTRON CAPTURE REACTION BY IMPORTANT FISSION PRODUCTS WITH A HIGHLY SENSITIVE DETECTOR

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The accurate neutron capture reaction cross sections of important fission products are indispensable for the development of an innovative nuclear reactor which aims at high burn-up or at the incineration of transuranic elements. The purposes of the present study were (1) the measurements of capture cross sections and capture gamma-ray spectra of Nd-144, 146, Eu-151, and Dy-164 in the neutron energy region of 10 to 800 keV with a highly sensitive detector, (2) the theoretical analysis of the present experimental results, (3) the comparison of the present results with those for Sm-147, 148, 149, 150, 152, 154, Nd-143, 145, and Dy-161, 162, 163, and (4) the investigation of the mechanism of neutron capture reaction by important fission products.All measurements were made with the 3UH-HC Pelletron accelerator, the highly sensitive detector, and the data acquisition system of the Research Laboratory for Nuclear Reactors at the Tokyo Institute of Technology. Highly enriched samples were employed in the measurements. The measurements were performed for Nd-146, Eu-151, and Dy-164 as scheduled, but the measurement for Nd-144 was not performed because of a shortage of funds. The measurements for Er-166, 167 were, however, additionally performed. As a result, the capture cross sections of those five isotopes were derived with the errors of about 5% in the neutron energy region of 10 to 600 keV. The capture gamma-ray spectra of those isotopes were also derived with good accuracy. The theoretical analysis was performed for the experimental results of those isotopes, Sm-147, 148, 149, 150, 152, 154, Nd-143, 145, Eu-153, and Dy-161, 162, 163. The results of the present study have been already published.