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Navigation to
sections:
The Microanalysis System
What makes a Good Detector?
The Pulse Processor
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Role of the pulse processor
Analog pulse shaping
Time variant shaping
Digital pulse shaping
Fixed process time
Adaptive pulse shaping
Resolution & count rate
Pulse pile-up protection
Comparing different pulse processors
Summary
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The pulse
processor
The Role of
the Pulse Processor
The charge liberated by an
individual X-ray photon appears at the output of the preamplifier as a
voltage step on a linearly increasing voltage ramp (Fig. 13a). The
fundamental job of the pulse processor is to accurately measure the energy
of the incoming X-ray, and give it a digital number that is used to add a
count to the corresponding channel in the computer (Fig. 13c). It must also
optimize the removal of noise present on the original X-ray signal. It needs
to recognize quickly and accurately a wide range of energies of X-ray events
from 110eV up to 80keV. It also needs to differentiate between events
arriving in the detector very close together in time, otherwise the
combination produces the spectrum artefact called pulse pile-up.
Signal
measurement
There are a number of ways of
measuring the size of the steps on the voltage ramp, which depend on the
type of pulse shaping being used: digital or analog.
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