PROPORTIONAL COUNTER CIRCUITRY
Radiation Detectors
The capacitor converts the charge pulse to a voltage pulse. The voltage is equal to the amount
of charge divided by the capacitance of the capacitor, as given in Equation 6-8.
(6-8)
V
Q
C
where
V = voltage pulse (volts)
Q = charge (coulombs)
C = capacitance (farads)
The preamplifier amplifies the voltage pulse. Further amplification is obtained by sending the
signal through an amplifier circuit (typically about 10 volts maximum). The pulse size is then
determined by a single channel analyzer. Figure 10 shows the operation of a single channel
analyzer.
Figure 10 Single Channel Analyzer Operation
The single channel analyzer has two dial settings: a LEVEL dial and a WINDOW dial. For
example, when the level is set at 2 volts, and the window at 0.2 volts, the analyzer will give an
output pulse only when the input pulse is between 2 and 2.2 volts. The output pulse is usually
a standardized height and width logic pulse, as shown in Figure 11.
IC-06
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