Electroscope Ionization Chamber Summary

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. Rev. 0 Page 41 IC-06