Research Report; Data Analysis of Neutron Cross Section Measurement by LLFP Nuclides
Furutaka, Kazuyoshi
This report describes a research done at Oak Ridge National Laboratory (ORNL) under the collaborative program on "neutron reaction cross section of long-lived fission fragment nuclides" between Japan Nuclear Cycle development institute and ORNL. The author has analysed the data on promptly emitted gamma rays in thermal neutron capture reaction by a LLFP nuclide, Tc, and deduced its reaction cross section during his residence on ORNL. In the analysis, a total of 1086 gamma rays were confirmed as prompt transitions in Tc emitted the reaction. From the data for these gamma rays, a decay scheme was constructed. Six of the prompt gamma rats were regarded as transitions to the ground-state of Tc. By summing-up intensities of the six transitions, a lower-limit for the reaction cross section was obtained to be 21.370.62b. From the yields of the gamma rays in Ru, which are produced by beta-decay of Tc, the reaction cross section was also obtained to be 22.81.8b. On the other hand, the reaction cross section obtained from intensities and energies of the observed gamma rays amounted only to 6.65b, which suggested that there remained a large number of high-energy gamma rays which are too weak to be observed.