469. 中国第3回核爆発実験による強放射能粒子

抄録

Highly radioactive fallout particles, originaing from the 3rd Chinese nuclear test explosion, were found on the roof of a building of the National lnstitute of Radiological Sciences, Chiba, Japan, and their properties were measured. The density of the particles distributed on the ground was about 4 particles/mm². The gross β-activity due to the fallout particles 2 days after the explosion was about 5, 600dps/mm². The decay curves were measured on the particles collected, which revealed some differences between individual particles. Particle size distribution ranged from 3.5μm to 23μm and seemed to have small cut properties.
The particle activity was well proportional to the volume. Their specific activity was estimated at 0.44dps/μm³ 10 days after the explosion.
The γ-ray spectra of the particles isolated from the filter of an air liner and of the residue of the filter were measured. Above results were compared with those from the 1st and the 2nd Chinese explosions.