Download Quality Control Procedures Applied to Nuclear

6. PEAK SHIFT VERSUS COUNT RATE
Peak shift versus count rate appears to the user as equal to count rate non-linearity but
electronically this is due to a poor baseline restoration. Therefore, this feature also has to be
tested so that one knows about the behaviour of the base line restoration.
Test description:
In this set of measurements one has to monitor the peak position and peak shape. The pulse
generator was set to the random mode and in the SCA system the LLD was set to a fixed
level. When the counter starts counting, the dial setting for pulse amplitude of the random
pulse generator has to be monitored by the dial setting for each count rate. The test set-up is
presented below.
Fig. 6. Set up for peak shift versus count rate measurement.
TABLE 8. PEAK SHIFT VERSUS COUNT RATE.
Count
rate
Dial setting of pulse
Deviation Dial setting of pulse
generator when system
generator when NIM test
under test starts counting
electronics starts counting
Deviation
200 cps
500 cps
1 kcps
2 kcps
10 kcps
7. CHI SQUARE TEST
This test is an overall QC test and gives an indication of the proper operation of the counting
system when applying random pulses from a radioactive source. In a set of 10 measurements
50