i
12
a 3-ineh lead Anton pig with a Nuclear-Chicago Model 181 Scaler,
é
Background varied from 18 to 32 ¢/min.
Correction Factors:
per unit volume or weight,
To convert counts to disintegrations
corrections were made for sample size,
self-absorption, geometry, backscatter and decay.
The correc-
:
greed
tion factor for counting efficiency, which includes self-absorp#6
|
* ‘
tion, geometry and backscatter, was determined from counting
:
plates of known weights of potassium chloride with known disin-
4
+8,
tegration rates for tO,
ae)
3.4 to 3.8; and was for filter paper, 3.3; and for water samples: 3
sy | |
4.0.
8: I
For plankton this factor ranged from of 4
All samples counting background or less were taken AS zero,
The samples counted aboard ship were counted within a few
uf
=
hours from time collected and therefore were not corrected for.
1
decay.
|
collection.
:
to 5 inclusive) one decay curve was used and for sections 6 toa 10 4
‘is |
.
The samples counted at EMBL were corrected to the day of:
For samples collected west of Eniwetok (sections 1
a second curve was
used (Fig. 9).
For the former the half life
3
i
was less than two days for the early part of the curve and about a
;
six days for the end of the observation period.
For the latter “2
ie ‘i
curve the half life was about four days.
‘e
factor for decay was 15 but the factor usually was much less.
:
7 4
»
°
i? i
:
The maximum correction s
“a
Fish samples were corrected to the day of collection using the Ad
|
plankton decay curves and absorption factors.
Contours:
‘
Contours have been used to show distribution of *.:
use of contours adequately shows the relationships between the
radioactivity of the plankton and water samples, but the contours
hg
Be
to
:
e