Model 2929 Scaler Technical Manual Section 6
Ludlum Measurements, Inc. Page 6-3 January 2016
The following procedures describes the determination of the operating
voltage for a Model 43-10-1 detector, which is commonly used with the
Model 2929 dual channel scaler. Note that certain criteria must be met for
the background counts, source efficiencies, and crosstalk.
1. Connect the Model 43-10-1 to the counting instrument with proper
cable.
2. Place a calibrated
99
Tc source in the sample holder. Close and lock
the sample drawer.
3. Adjust the counting instrument HV until it receives at least 27% 4π
efficiency
4. Decrease HV by 25 volts.
5. Record the HV.
6. Record the
99
Tc source count and beta crosstalk in the alpha
channel.
7. Remove the
99
Tc source and record the background count in the
alpha and beta channels.
8. Place a calibrated
239
Pu source in the sample holder. Close and lock
the sample drawer.
9. Record the
239
Pu source count and the alpha crosstalk in the beta
channel.
10. Increase the HV by 25 volts.
11. Repeat Steps 5-10 until one or more of the following conditions
happen:
a. Beta background exceeds 80 cpm
b. Alpha background d exceeds 3 cpm
c. Alpha crosstalk in the beta channel
exc14eeds
10%
d. Beta crosstalk in the alpha channel exceeds 1%.
12. The operating voltage should be selected at a point where:
a.
99
Tc efficiency greater than or equal to 27%.
b.
239
Pu efficiency greater than or equal to 37%
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