recorder and analyzer, and then by varying the gain of the
amolificr and the fine pulse-heinht adjustment on tne recorder until total absorption peatts from standards of known
samma energies
(He 203 |
Na 2S ana cst37)
fell atv the appro-
priate positions on the recarding paper (Fig. 2).
It was
found that tnis calibration was very stable, requiring only
an occasional small adjustment in the zero-set control of
the recorder to allow for variation in paper placement and
ruling defects on the paper.
That the equipment was essen-
tially stable in the Y direction was snown by periodic
checks with the 60-cycle test position of the count-rate :
meter and by the linearity of the decay curves on semilogarithmic paper of the calibrated standards.
Pulse height spectra were recorded for each sample on
standard gain (3 Mev full scale) and on "high” gain-amplifier gain increased by a factor of four
(0.75 Mev full
scale)-~in those cases where the strength of the sample
allowed it.
How long the taking of periodic recordings of
each sample could continue after shot time before the count
rate became too low for statistically significant results
depended of course, on the original strength of the sample.
On nearly all of the standard-gain records, a calibrated
Na
22
standard source was recorded on the same sheet ina
different color ink, while on the high-gain records a
9