GBS Elektronik MCA-527 - Manual (Page 66)

MCA527
11. Bad resolution in a HPGe spectrum or from a test generator, specially at high
amplification factors
● Check electrical noise and EMC compatibility of surroundings. Some laptops
and also some switch mode power supply battery chargers may disturb.
Remove all connections from the MCA to ground or to mains voltages. Try a
different computer / laptop / palmtop.
● Winding the cable to the detector / computer several times around a ferrite ring
also may help
12. While opening a spectrum, the MCA program tells "Wrong data format" or "data
format error"
● spectrum was created by another program or another program version. Check
results, just ignore.
13. too high count rate
● Keep a bigger distance to radiation source. Try a less sensitive detector. Watch
for your personal safety!
● Check detector
● Check for disturbances of switch mode power supplies etc.
Typical errors which may be observed with the detector preamplifier signal are:
●
Rise time is too slow. This may cause degraded resolution in some cases. Increase
flattop time.
●
The fall time is too fast (time constant resp. 1/e fall time < 40µs). This causes that
the pole-zero setting cannot be correctly adjusted. Consequences may be peak
shift and peak broadening with higher count rates. Try direct input or try to use
another preamplifier.
●
Preamplifier signal exhibits ringing: This may trigger the Pile up rejector and lead to
missing parts of the spectrum. Try a different trigger filter or switch PUR off.
●
LF noise on the base line: Try BLR setting =1 or LF reject.
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