after burst received considerable theoretical study, the results were of
little use for evaluating the radiation risk to piloted aircraft or the
flight time within the cloud necessary to collect adequate samples at
relatively late times after burst.
Scientific personnel measured the radiation within bomb clouds and
reduced the data to equations.
Such equations included intensity in
roentgens per hour and this time in hours after burst and the numerical
constant was the intensity observed one hour after burst,
This curve
represented the decrease with time after burst in "peak intensity" within
the cloud,
Such
peak intensities
are found in the most persistent layers
of the main cloud at altitudes where isokinetic streamline airflow exists,
In the absence of cloud dispersion similar equations expressed the decrease
of the ganma radiation with time after one hour after burst as a result of
the radioactive decay of the source material.
The first type equation served for operation planning purposes with
the intensities within the cloud assumed to be independent of yield and
altitude so long as sampling of the main cloud only was considered,
A
general rule which personnel applied to lower level sampling was that
radioactive material and hence radiation intensity in the stem decreased
in concentration tenfold for every 10,000 feet below the base of the main
-8
cloud when burst conditions were constant,
Estimation of the In-Cloud Radiation Exposure Required
Within time limits defined by the radioactive intensity in a cloud
the radiation exposure received by a sampling aircrew was controlled to
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pt ge Ge.