Capture Cross Section Measurements of Long-lived Fission Products in the Resonance Neutron Energy Region

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In the current study, neutron capture cross sections of longlived fission products (LLFPs) have been measured by the neutron time-off-light method using a 12.7 m flight path and a 46 MeV electron linear accelerator (linac) at the Research Reactor Institute, Kyoto University (KURRI). The earlier experimental and the evaluated nuclear data have been investigated by the current results obtainedWe have measured the capture cross sections of Tc-99, Rh-103, In-115, I-127, I-129, Cs-133, and Pr-141 as LLFPs. The nuclides of Tc-99 and I-129 are radioactive materials and the others are non-radio active stable isotopes. Making use of the linac TOF method and the prompt capture gammaray measurement, the capture cross sections have been measured from a few meV to several tens of keV. For the capture cross section measurement, an assembly of 12 pieces of Bi_4Ge_3O_<12> (BGO) scintillators (each size; 5cm x 5cm x 7.5cm) have been used as a total energy absorption detector, which has a through hole t … More o set the capture sample at the center of the detector assembly. The incident neutron energy flux/spectrum has been monitored with the ^<10>B(n, α ) standard cross section, and the relative capture cross section has been normalized to the well known reference value at 0.0253 eV. For the measurement of Rh-103, In-115 and Cs-133, the absolute capture cross section has been obtained by using a saturated count method at the major resonance peakThe earlier experimental and the evaluated data for the above capture cross sections have been compared with the current results. These capture cross sections have not been always satisfied with the data-quality and quantity, especially in the lower energy region below about 10 eV. For some nuclides or the reaction cross sections, no experimental data have been existed or the discrepancies have been seen between the current data and the earlier experimental and the evaluated data. We could provide the useful data for the investigation or the re-evaluation of the capture cross sections Less