24
Source exposure conditions :
In calibration device model 773, serial number 397
The gamma-ray emission of the sealed source herein described was measured with a Radcal Corporation model 20X5-180
Ion Chamber whose relative response to cobalt
60
, cesium
137
, and 50 kvp X-rays had been determined by a National Institute
of Standards and Testing, approved calibration laboratory. Sensitivity of the Ion chamber is monitored by reference to a NIST-
Traceable cobalt60 source. Readings were corrected for atmospheric temperature and pressure and for ambient air scattering
and absorption. The source was measured with its axis of symmetry perpendicular to the line joining source and chamber
center. The reported output represents the intensity expected in the absence of air and surrounding objects. It is believed to
be accurate within +/- 7%, made up of the stated +/-5% uncertainty of the NIST source calibration and the +/-2% estimated
precision of comparison.
Standards
Laboratory
Report
T
est No.
5923
MilliCuries
161.5
MilliRoentgens/hr
at 1 meter
51.7
Source
Identification
S-1028
Date Measured
05-AUG-2002
Isotope
Cesium
137
Half Life
30.2years
Rhm/Ci
0.32
GAMMA RAY SOURCE CALIBRATION
mersham QSA
DATE
40 North Avenue
Burlington Massachusetts
Signed___________________________
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