By sampling time, the bomb cloud had separated into three major portions:
the
top portion rubbing up against the bottom of the overcast at 30,000 feet, a
middle portion centered at 25,000 feet and the lower portion appearing to the
eye like red dirt shoveled over the top of the undercast at 15,000 feet,
All
portions of the bomb cloud maintained a strong reddish brown color and although
semi~transparent in appearance, were always readily visible; particularlywith
the aid of brown sunglasses or helmet visors,
SAMPLING MISSION
Because of the apparent thinness of the cloud, Tiger White I was directed
in at 30,000 feet and plus 50 minutes for a brief sniff and reported radiation
intensity averaging 40 roentgens per hour,
About this time, the landing.field
was closed by heavy rain so White I was held off for 23 minutes before being put
into the same portion for his sampling run.
Cloud intensities had dropped by a
factor of 4 to 5 in this comparatively brief time.
Tiger White II was put in at
25,000 feet and plus 98 minutes and found radiation intensities about the same.
Blue I and II were directed into the visible bottom of the cloud spread along the
undercast at 15,000 feet and collected a required sample with no difficulty, even
though the activity encountered was in spots and patches,
Yellow I and II were
directed into the middle portion of the cloud at 2 hours after burst and encountered radiation intensities averaging from 4 to 5 roentgens per hour, about as
expected for that time.
NUMBER RATIOS
The number of fissions measured in the samples by Radio-Chemistry at Los
Alamos averaged about 77% of the number predicted at PPG from observation of
radiation levels of sample papers as removed from the aircraft,
The discrepancy
was more than compensated for, by the pre-planned increase in pilots dosage based
on experience from preceding REDWING shots.
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