Fluke Biomedical 943-27 Detector - Manual (Page 22)

943-27 Beta Scintillation Detector
Operator Manual
4-8
7. Wait a minimum of 1 minute, and then observe the 960 display. Compare the value
displayed to the calculated value in step 3 above. The observed value must be within +/-
2% of the calculated value.
8. If the value is within the required tolerance, proceed to step 10.
9. If the value is not within the required tolerance, adjust the scaler high voltage (96SF, R8)
until the observed value falls within the required tolerance. If the observed value is too
low, increase the high voltage. If the observed value is too high, decrease the high
voltage.
NOTE
DO NOT adjust the high voltage after this point
10. Remove the detector from the source holder and lay it on the ground. Replace the end
cap on the source holder.
11. Wait 5 minutes, and then observe the 960 display. The displayed value is the
background current for this detector. The value must be less than 4.0 x 10
-11
amperes. If
greater than 4.0 x 10
-11
amperes, the det4ector should be returned for repair or
replacement.
12. Decay to the present day the “net current” value printed on the calibration data sheet,
under the heading of customer sources, for the Strontium-90 source.
13. Remove the cap from the Strontium-90 source holder. Place the source holder on the
ground. Insert the detector into the holder.
14. Wait a minimum of 1 minute, and then observe the 960 display. Compare the value
displayed to the calculated value in step 12 above. The observed value must be within
+/-6% of the calculated value.
15. Remove the detector from the source holder and lay it on the ground. Replace the end
cap on the source holder.
16. Decay to the present day the “net current” value printed on the calibration data sheet,
under the heading of customer sources, for the Chlorine-36 source.
17. Remove the cap from the Chlorine-36 source holder. Place the source holder on the
ground. Insert the detector into the holder.
18. Wait a minimum of 1 minute, and then observe the 960 display. Compare the value
displayed to the calculated value in step 16 above. The observed value must be within
+/-6% of the calculated value.
19. Remove the detector from the source holder and lay it on the ground. Replace the end
cap on the source holder.
20. If all 4 values fall within the required tolerances, the detector is calibrated. Record the
values obtained as well as the detector high voltage. The high voltage may be measured
at the 1000:1 test jack on the 960 front panel.
21. If any of the 4 values does not fall within the required tolerances, return the detector for
repair or replacement.
22. Re-install the detector into the sampler.
23. This concludes the field detector calibration procedure.