FAST ComTec CSPA10 User Manual page 16

R : pulser and biased detector connected
D
R : puser without detector connected
E
If R is not less than 2.0 keV for two microseconds unipolar Gaussian shaping time constant, the problem
E
is in the electronics and probably in the preamplifier.
If R is acceptable, but R
E
then the problem is either in the detector (microphonics, excess leakage current noise, breakdown due to
moisture or grime on the detector output connectors), or in the preamplifier (leaky input capacitor, dirty or
moist detector load resistor, dirty or moist detector input connector).
If R and R are acceptable, but the live spectrum (R
E D
probably in the detector (bad detector, poor charge collection, insufficient bias) or in the electronics
following the preamplifier (count rate too high, improper amplifier pole/zero cancellation, wrong main
amplifier time constant, wrong amplifier shaping-bipolar vs. Unipolar, improper amplifier shaping for the
ADC being used, ADC cannot take the count rate, amplifier or ADC drift). These many alternatives are not
easy to check. Substituting, one-by-one other detectors, preamplifiers, amplifiers, and multichannel
analyzers may help pinpoint the problem. Checking the above common problems will aid in spotting the
source of trouble.
14
Operating Instructions
is greater than 2.0 keV plus 10 eV/pF detector and connection capacitance,
D
) is not as good as expected, the problem is
S
F
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