exposure period for background
The background
exposure was essentially all contributed by cosmic radiation during the
3-month exposure period and during
the aircraft flight to LLL.
Additional TLD's were stored on
the periphery of the lead pig to
identify possible inadvertent
exposures.
The average background
exposure for the two types of TLD's
was subtracted from all field
Nal scintillator response — uR/h
determination.
measurements so that the results
represent only the terrestrial
radiation exposure rates.
o
We
found that sunlight had a negligible
effect on this packaging arrangement.
Fig.
!
L
l
!
Comparison of responses of
the Nal scintillator and the
2.
pressurized ion chamber.
results obtained with the Nal
linear, deviates more markedly from
scintillator and the pressurized
ion chamber is presented in Fig.
2.
the L:l relationship.
The TLD results indicated that
The ion chamber readings have been
the cosmic-ray
contribution at that latitude.
i
lon chamber response — uR/h
The correspondence between the
reduced by 3.3 uR/h,
|
10 20 30 40 50 60 70 80
The
the CaF,
TLD's overresponded by
2
approximately 214 relative to the Lif.
figure shows that the Nal seintilla-
This is consistent with similar
tor overresponded because of its
studies made at Enewetak Atoll and
nonlinear energy characteristics.
with environmental monitoring per-
The discontinuity at about 30 UR/h
formed by LLL in the U.S.
occurs at a range switching point
response varies with energy and this
on the scintillator.
ratio (1.21) corresponds to an
Three locations
The over-
were measured on both Low and high
average gamma energy of about 500
range, and those results are
keV.
shown
in Solid
On the
circles.
This is reasonable based on
the Ca¥,
2
enhanced low-energy response
13
scintillation instrument's low
and the predominance of
range of 0 to 30 uR/h, a correspondence
activities distributed in the soil.
near 1:1 is observed.
the correspondence, though
as
JUL Go 08
aera
range,
On the higher
To assess
“os
the beta contribution
to the Lil’ exposure rates,
various