Radiation DetectorsELECTROSCOPE IONIZATION CHAMBERA small piece of quartz fiber is mounted across the end of the gold-plated quartz fiber and servesas an index that is viewed through a microscope equipped with an eyepiece scale. The quartzfiber is charged by a battery pressing the charging key. As the quartz fiber is being charged, itis deflected from the support. It takes approximately 200 volts to produce full-scale deflectionof the fiber. A glass window at the end of the ionization chamber allows for exposure of thefiber. As the gas (air) is ionized by the incident radiation, the fiber moves toward the positionof zero charge. Due to the electroscope’s dependability, simplicity, accuracy, and sensitivity, itis widely used in gamma radiation measurement.A self-reading pocket dosimeter is an example of an electroscope ionization chamber. Pocketdosimeters provide personnel with a means of monitoring their radiation exposure. Thedosimeters are available in many ranges of gamma exposures from 0 through 200 milliroentgensto 0 through 1000 roentgens. The sensitivity of the instrument is determined at the time ofmanufacture. Appropriate scale markings are provided with each dose range.SummaryThe operation of an electroscope ionization chamber is summarized below.Electroscope Ionization Chamber SummaryThe 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, andthe fiber moves towards the zero charge position.Rev. 0 Page 41 IC-06
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