Radioactive fallout at Asahikawa, Hokkaido in April, 1955

[摘要] A remarkable artificial radioactivity was found in a fallout collected at Asahikawa on April 12, 1955. Its specific activity was determined to be 2, 660cpm/g by our measurement carried out on April 22. This is equivalent to about 22.5 mμC/g. The quantity of fallout amounts to ca. 1.9g/m2. The ordinary chemical analysis was made, and it was clarified that the sample was to be a loess distributed in North China. It is also explained that the radioactivity of the sample is ascribed to the fission products yielded in an experiment of the atomic weapon carried out at Nevada, U.S.A. In addition, the result of radiochemical analysis is described.

[学科分类] 大气科学