This separation procedure
for molybdenum has been described by Gunn,
Hicks, Stevenson and Levy, Physical Review,
107,
1642 (1957).
Analyses are >
.
run in triplicate or quadruplicate to minimize experimental errors.
Treatment of Data.
c.
subject to two corrections.
Each individual counting rate measurement is
After recording an event, a counting instrument
is insensitive for a period known as the "dead time", which we may represent
by the symbol +. Then if there are R events per unit time, the instrument is
insensitive for a time R17 and operative for a time 1-R7 in each unit time.
The true counting rate then is Rx1/(1-R+r).
In the instruments used the dead
time 7 is so small (5 to 6 » sec) that at ordinary counting rates the correction
may be neglected.
There is also a correction (due to the "background" rate of
the counter) that :is the counting rate in the absence of the sample.
Background
may be due to cosmic radiation, radioactive contamination of the counter, or
electronic noise in the amplifier circuits; it is considered to vary only slowly
with time.
A measurement of the background rate made shortly before or
after the measurement of the sample counting rate will yield a number which
is subtracted frorn the measured rate to give the true counting rate of the
sample.
The observed corrected counting rate fora pure sample of Mo?? will
decrease exponentially with a half-life of 66.04 hours.
Te?? and Te? 9™ daughters
The activity of the
activities are 99 percent adsorbed by the air gap
andcounter window and thus can be neglected.
The counting rate for each
sample can be extrapolated back to the time oi the detonation to give an "initial
rate'' Ro.
The calculations are then as follows:
Let
_
weignt PhMoO, recovered
Y “ Weight of Mo as PbMoO, added as carrier
a= volume of aliquot taken for analysis
volume of total sample
oe
= mg/cmair gap + counter window
'
ct
fosa = proper ordinate of Figure 16
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