surrounded
each
counting
methane-flow
used
chamber
in con-
junction with the Nucleometers to give a background of only about
WT-616
placed on
45-50 counts per minute (c/m).
The same counting equipment was
used throughout the seven years covered by this report.
Counting time followed the schedule of WT-616:20 during the
tes,
ernight at
alcohol to
ig of 0 5
earlier counting:
C/m, sample
Counting time,
plus background
minutes
<-500
500-1000
1000-2000
> -2000
rated
rds
For later counts, as more
machine
time became
available,
longer counts of from 30 minutes to several hours were frequently pos-
arrow,
be in-
ixation —
ion
20
10
5
2
of
sible for the low-counting samples.
The absolute level of radioactivity as indicated in the column of
Table 1 headed ‘Plate count, 1000 days," serves as an index to the
rellability of the points.
‘ination
one
1ation.,
Graphing and Reproduction
Values from the decay data-sheets were plotted as circles on
thin logarithmic graph paper.
Even where circles overlapped, almost
all of the values were graphed.
the nearest
curve, and lines
Free, outstanding circles pertain to
connect
those points
whose identity was
ee
ast
eTee
os
al
nield