3.2 ALTITUDE ABSORPTION MEASUREMENTS
Data on radiation versus altitude, over land, are summarized in Table 3.1. Scintameter
survey meters were used for the measurements during helicopter missions. A Top Hat radiation
detector and a scintameter were used in the P2V-5 aircraft.
The differences in the absolute values of the readings in the P2V-5 are due to the difference
T
rPryyrt
T
TUT
TT Et
(00
T
87 pct of Calibrations
3
o£
|
Radiation , mr/hr
Fell Within These Limits
L
L
/ }
i!
He
4 i]
id!
All Calibrations Were
Within These Limits
TTT
—
0.0! fy
0.007
0.2
_t
0.4
41
0.6
t
0.8
_
1.0
L
2
Reading , milliamperes
Figure 3.1 Summary of 37 pre- and postflight calibrations of Top Hat
radiation detectors.
in the energy response of the two types of detectors.
The scintameter, TH-3, uses a sodium
iodide phosphor, which is more sensitive to soft gamma radiation. The Top Hat detector uses
a plastic phosphor and has a response that is nearly energy-independent. The response of the
two types of instruments is summarized in Figure B.2. Because fresh fission products have a
25