DETECTOR VOLTAGE
Radiation Detectors
DETECTOR VOLTAGE
Different ranges of applied voltage result in unique detection characteristics.
EO 1.5
Given a diagram of an ion pairs collected -vs- detector
voltage curve, DESCRIBE the regions of the curve to
include:
a.
The name of the region
b.
Interactions taking place within the gas of
the detector
c.
Difference between the alpha and beta
curves, where applicable
Applied Voltage
The relationship between the applied voltage and pulse height in a detector is very complex.
Pulse height and the number of ion pairs collected are directly related. Figure 6 illustrates ion
pairs collected -vs- applied voltage. Two curves are shown: one curve for alpha particles and
one curve for beta particles; each curve is divided into several voltage regions. The alpha curve
is higher than the beta curve from Region I to part of Region IV due to the larger number of ion
pairs produced by the initial reaction of the incident radiation. An alpha particle will create more
ion pairs than a beta since the alpha has a much greater mass. The difference in mass is negated
once the detector voltage is increased to Region IV since the detector completely discharges with
each initiating event.
IC-06
Page 14
Rev. 0
