.
.
|
'
a
Notes on Mtg, 25 Aug '51
Plank explained the first difficulty:
In radiochemical analysis
for efficiency, one simply determines the number of fissions vhich a sample
represents and then, knowing the fraction of the bomb in that sample, can
determine total number of fissions.
It is primarily a question of back-
ground, ascertained by a chemical blank, which makes the accuracy of the
determination decrease with lesser fraction of bomb in the sample. Because
the size of the uranium blank of a particular sample is not known accurately,
radiochemical efficiencies become increasingly uncertain as the ratio of
the average blank to total uranium found increases. For this reason,
samples less than ~ 5 x 10°13 of @ super will yield unreliable radio-
chemical efficiencies,
Unfortunately, there appears to be a correlation between average
frection of the bomb collected and the yield which indicates that sample
size follows an inverse logarithmic function of the yield.
If one plots
the logarithm of the average sample size, & (in terms of fraction of bomb
it contains), from Greenhouse measurements vs the yield, E, the points
fall along ea straight line, as shown in Fig. 6.
1078 |
Fig. 6
10”?
Correlation Between
OF
and Yield (Greenhouse)
,
.
I
LB
Average Sample Size
.
©
107}
G
20"*
|
0
+
+
100
200
E (kilotons)
DELETED
DELETED
—ct
300
DELETED
(the
numberatmeeting was és later investigation of the curve shovs
1050, @ number which is so large as to be completely unbelievable on any
Physical basis at all.)