APPENDIX I
STANDARDS CALIBRATION
S\2 er —..-
Calibrated standard sources were supplied to this
group by Analytical and Standards Branch of Chemical Technology Division to allow checks to be made of the relationship between area of total absorption peaks and their
associated photon intensities, and to provide standards of
known energy for record by record energy calibration.
The
calibrated standards used were 75.6 (+4 percent) microcuries
of Na ?2ana 145 (+5 percent) microcuries of He“ ° .
The
ne
standards were calibrated on May 18, 1956.
In order to use these standards to check the correct-
ness of the I/A versus E curves, corrections had to be made
in the source strengths listed.
In the case of Na&e the
standards were calibrated in terms of positron emission
alone, so that to arrive at the 1.28 Mev photon intensity,
account had to be taken of the 6tol1l percent electron cap15,16
ture ° >
When this correction is applied, the original
1.28 Mev photon source strength becomes 80.4to 84.9 "micro-~
curies" or 2.97 X 10° to 3.14 xX 10° photons per second.
To
compare this number to that obtained by multiplying the
area of the total absorption peak by I/A for 1.28 Mev, the
area must first be found by extrapolating the decay curve
pack through the calibration date.
50
This area is 1.54 (+2