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John C. Sugher, U. D., Mirector
vay 1b, 195)
“iviaion of Biology and Medicine
Corvion HN, "mring, MNealth Physicist
Biophysics Branch, Division of Biology and Wedicine
DATA OW SOTL SAMPLFS COLLFCTPD ON THE ISLANDS OF THE PACIFIC FOLLOW
ING "HE FIRST DETONATION AND ALSO mE DOSE RATE READINGS AT TE
SAME LOCALITIES,
Attached (Arex I) are data on soil samles collected on the islands
of the Pacific following the first cetonation and also the dose rate
readings at the same localities. ‘ne method of evaluating stch data
is to try to establish relationships between different mits if pos
sible. One useful relationship would be the conversion of disinte-
creations per minute per cram of soil to miliiroentgens per hour of
gamma radiation at a three-foot height or vice versa.
Larson's work with soils around ‘PG during we spring 1953 tests
indicated the following relationship:
aqg.ft. beta counts of
soil (after absorption and geometry ‘oreed
nes —— 1 or/hr cama
at 3 feet.
‘te found that essentially all of fhe activity was in the
firat one inch of top soil,
|
Po
DATE
f
Deere &
—-m es
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BY AUTHORITY OF DOEsEPC
0160S
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CLASSIFICATICN CaANCELLED
In collecting soil on the Pacific Islands good care was taken to
collect one square foot of surface (in fact, templets were mace for
this ourpose). It was impossible, however, to scoop up the soil to
a uniform depth so the rule followed was to collect to one inch or
greater.
If the fallout activity in the Pacific Islands also was
contained in the first one inoh, the additional soil below this
contributed mass but little activity to the sample,
By taking the
disintegrations per minute per gram (after a thorough mixing) and
multiplying by the total nusber of crama for each sasple one should
arrive at the activity per square foot,
The plot of beta disintegrations per ninute per gram of soil versus
ar/hr of gamma at 3 feet is show on the attached graph.
lation is not too geod.
ily drawn on the graph,
The corre-
For references, several curves are arbitrar‘the data strongly suggest that less than
tndsae ft. 1a equivalent to l ar/hr. For lower levels of activity
|data are more of the order of 2 pel 39. ft.—— 1 or/br and for
fWvelbs.afactivity lesa than
3q ten edadmeet if
;
codeve to su
ely
scatte
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