Radiation Detectors
ELECTROSCOPE IONIZATION CHAMBER
A small piece of quartz fiber is mounted across the end of the gold-plated quartz fiber and serves
as an index that is viewed through a microscope equipped with an eyepiece scale. The quartz
fiber is charged by a battery pressing the charging key. As the quartz fiber is being charged, it
is deflected from the support. It takes approximately 200 volts to produce full-scale deflection
of the fiber. A glass window at the end of the ionization chamber allows for exposure of the
fiber. As the gas (air) is ionized by the incident radiation, the fiber moves toward the position
of zero charge. Due to the electroscope’s dependability, simplicity, accuracy, and sensitivity, it
is widely used in gamma radiation measurement.
A self-reading pocket dosimeter is an example of an electroscope ionization chamber. Pocket
dosimeters provide personnel with a means of monitoring their radiation exposure. The
dosimeters are available in many ranges of gamma exposures from 0 through 200 milliroentgens
to 0 through 1000 roentgens. The sensitivity of the instrument is determined at the time of
manufacture. Appropriate scale markings are provided with each dose range.
Summary
The operation of an electroscope ionization chamber is summarized below.
Electroscope Ionization Chamber Summary
The electroscope ionization chamber is charged using a battery.
Charging causes the quartz fiber to be deflected from the support.
When radiation ionizes the gas (air) in the chamber, the charge is reduced, and
the fiber moves towards the zero charge position.
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