gas flow counting chamber.
Hence the correction factor was
approximately 2.0.
Backscatter.
Backscatter was previously determined for
p32 in our Nucleometers as being 30 percent (see p. 24 of
AECD-3446).
The same correction factor, 35 = 0.77, was
used again this year.
Coincidence.
The loss of counts due to coincidence was
determined empirically.
Small amounts of p32 were dried on
tinfoil and the pieces of the P32 tinfoil, for which the
counting rates had been determined, were placed one at 4
time side by side on the counting plate.
After each piece
of the p32 tinfoil had been placed on the plate a count was
made.
The expected count, which was the sum of the individual
counts, was divided by the observed count to determine the
correction factor.
For observed counts less than 80,000 e/m,
no correction was made for coincidence; for counts of 80,000
to 160,000 per minute, the correction factor was 1.01; for
counts of 382,000 to 392,000 per minute, the correction
factor was 1.07.
Correction factors were also determined
for intermediate values.
For small corrections the counting
rate as determined theoretically from the formula N * tout
held true (N = true counting rate, n = observed counting
rate, and t = recovery time of register = 5 microseconds).
Background.
The background values were determined by
interpolating between background counts at the point (i.e.,
time) when the sample count was made.
Usually about five
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