| Research Abstract |
The main objectives of this study are (1)improvemant in the sensitivity of gamma-ray detection system, (2)systematic measurement of fast-neutron capture cross sections and capture gamma-ray spectra for Zr-90,91,92,94 and Sn-117,118,119,120,122,124, which are impurity isotopes of the long-lived fission products Zr-93 and Sn-126, respectively, (3)improvemant in accuracy of theoretical prediction by the elucidation of fast-neutron capture reaction mechanism for Zr and Sn isotopes through the systematic analysis of experimental data, and (4)accurate evaluation of fast-neutron capture cross sections of the long-lived fission products Zr-93 and Sn-126. The summary of research results are as follows :
(1) The existing main NaI(Tl) detector was replaced with a larger NaI(Tl) detector with a diameter of 15 cm and a length of 30 cm, and the sensitivity of gamma-ray detector was improved.
(2) The systematic measurement was performed for Zr-90,91,92,94 and Sn-116,117,118,119,120,122,124. The data processing was completed for Zr-90,91,92,94 and Sn-117,118,119, and the capture cross sections and capture gamma-ray spectra were derived for those isotopes.
(3) The derived capture cross sections and capture gamma-ray spectra of Zr-90,91,92,94 and Sn-117,118,119 were theoretically analyzed by using the statistical model in nuclear reaction theory, and information on the fast-neutron capture reaction by Zr and Sn isotopes was obtained.
(4) The evaluation of fast-neutron capture cross sections of the long-lived fission products Zr-93 and Sn-126 was performed based on the obtained information, and evaluated values were obtained tentatively.
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