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In carrying out the experiments listed above measurements
re made at approximately 60 different sites around the country.
b total data from all these locations allowed an intercalibration
our new NaI(T1) detectors with our well calibrated 5” x 3"
hector over a wide range of component and total dose rates.
results of these measurements along with a few other
msurements made in the Northeast before or after the trip
presented in Tables IV and V.
The total y dose rate
en in these tables is in most cases a composite of up to
cen
-his
3 of
caphical
it.
-
r separate determinations,
In
of
1 problems
column labeled F.O.
as well
7s
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irvey
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at
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nultaneous
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th the
rity;
ray
id
‘orrelation
for
\
wring
(2)
is the difference between the
al natural gamma dose rate and the total gamma dose rate.
cosmic ray dose rates are based on our determination of
tations.
on from
Several
since at most locations two
ization chambers and two NaI(T1) detectors were used.
ilarly the component dose rates given are the best values
ed on the data from both the 5" x 3" and 4" x 4" detectors.
mic ray ionization vs.
evious reports
K,
K,
U,
atmospheric pressure.°
As in our
and T represent the dose rates
daughters of 238y and daughters of 232Th,
from
respectively.
:
The accuracy of these dose rates is estimated to be + 20%
r U, + 3% for total gamma, + 0.3 ur/hr for fallout dose rate.
pse estimates are substantiated by the excellent agreement
tained between F.O.
(2) and total fallout values over a wide
hge of component and total dose rates.
The precision of
pingle Measurement of K, U, or T is about 5%, of fallout
Se rate about 10% and of the total dose rate about 2%.
:
The major field investigations listed above will now be
Bcussed in some detail.
survey of 1962 and 1963 Sites
i
i
Measurements were made at a number of the sites visited
ing the 1962 and/or 1963 field trips.
The results of the
2 and 1963 measurements as well as the 1965 measurements
= shown in Table IV.
These data indicate that fallout
els, as expected, are down from highs of around 5 wr/hr in
2 and 1963 to less than 1 ur/hr in most areas in mid 1965.
S is consonant with a more detailed study of fallout levels
‘the New York area.”
At many locations, especially in the central and Rocky
ntain states, the natural gamma levels appear to be
nificantly lower than in 1962 and 1963.
We believe this
—-9.