Time interval between nuclear detonation and formation of single fallout particles

Abstract

In the recent study on the mass-yield distribution of the fission products in a combined sample of 20 individual fallout particles from the May 14, 1965, Chinese nuclear explosion, we [Rao et al., 1966] found that the observed yields at mass chains 90 and 137 were significantly lower than the values expected from the U235 fission mass-yield curve. In this work we have studied the mass-yield distributions of the fission products in two single particles from the May 9, 1966, Chinese nuclear explosion, collected at Osaka, Japan (34°N, 135°E), and in one single particle collected at Fayetteville, Arkansas (36°N, 94°W). The fission product activities at mass chains 89, 91, 103, 129, 140, and 141 were found to be highly depleted in these particles. The extent to which the fission products at these mass-chains are deficient seems to depend on the half-lives of the gaseous precursors, on the volatilities of some of the fission products in the decay chains, or on both.