UNCLASSIFIED <SEGRET RM-1175-AEC 12-30-53 ~- 31 - Lale ian?) has presented an analysis of the JANGLE surfacejshot which shows the pattern of downwind fall-out as deduced from an serial survey after the detonation. The Summary Report: Weapons Effects Tests centered 20 miles downwind of about 550 ni” with 50 percent of and one centered ebout 60 miles downwind of about 520 mi” with « percent of the debris. From observations of the detonation it ayipe that the debris was separated into 2 clumps, the mushroom proper 13,000' and the top of the stem centered at 9000'. [centered at If it is assijmed that the debris settles at the same rate as the Stoke's law, fall fore spherical particle of Seu diameter, the maximum at 60 miles would have coma from the mushroom and the maximm at 20 miles would have come from the clump at the top of the stem. Thus there is some evidence that a large fractibn of a surface burst comes rapidly to the ground and that the rate of fafll of a 7Cy particle provides an estimate of the rate of settling. For the Mike shot the exact height of rise and the complete structure to the top of the cloud is not known. There is some rakher strong evidence, however, that there was a clumof debris, at what 1 the top of the stem, at about 60,000'. find be termed The report on fall-out difbtribution (3) shows a plot of the point of impact of 75y particles falling from] 60,000! end is shown in Fig. 1. 1045332 The time it would take such a particle th reach the ceegial SEeREE UNCLAYSIFIED LANL