@article{oai:soar-ir.repo.nii.ac.jp:00013016,
 author = {帶刀,  正},
 journal = {信州大学工学部紀要},
 month = {Dec},
 note = {An estimation of the elapsed time after nuclear explosion was made by measuring the activity ratios of y u Zr to y u Nb in the radioactive fallout. By means of a Ge(Li) γ-ray detector with high resolution, the photopeaks due to y u Zr 724.3 keV γ-rays and y u Zr 756.8 keV γ-rays were resolved clearly from each other, while those due to y u Zr 756.8 keV γ-rays and y u Nb 765.8 keV γ-rays belonging to the same decay chain (mass=95) were not completely resolved but took the form of complex photopeaks as shown in Fig. 2～Fig. 5. The area of each complex photopeak was resolved into two component peak areas by the two-component seperation procedure. The activities of the γ-rays were measured from the resolved photopeak areas, and the activity ratios Rb, Rc, Rd and Re were calculated, which represent the activity ratios of the γ-rays, [y u Zr 724.3 keV+y u Zr 756.8 keV] /y u Nb 765.8 keV, y u Zr 724.3 keV /y u Nb 765.8 keV, y u Zr 756.8 keV /y u Nb 765.8 keV, and y u Zr 724.3 keV/ [y u Zr 756.8 keV+y u Nb 765.8 keV], respectively. The numerical tables for the activity ratios Rb, Rc, Rd and Re expressed by the functions of the elapsed time after nuclear explosion were obtained by using an electronic computer (Table 4～Table 7). The experimental values of the elapsed time obtained from highly radioactive fallout particles due to the nuclear explosion in China on December 24, 1967 were in good agreement with the theoretical values obtained from calculation. It was found that the error of the elapsed time after nuclear explosion estimated from the activity ratio Rb independent of the branching ratio was smaller than those obtained from the other activity ratios Rc, Rd, and Re., Article, 信州大学工学部紀要 29: 1-18 (1970)},
 pages = {1--18},
 title = {放射性降下物中の ⁹⁵Zr と ⁹⁵Nb の放射能比による核爆発後の経過時間の推定について},
 volume = {29},
 year = {1970}
}