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Regional Basic Professional Training Course in Korea

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<strong>Regional</strong> <strong>Basic</strong> <strong>Professional</strong> <strong>Tra<strong>in</strong><strong>in</strong>g</strong> <strong>Course</strong> (BPTC) on Nuclear Safety<br />

Fig. (2.8) Voltage Dependence of a Gas‐filled Detector: Region I represents the voltage levels at<br />

which partial recomb<strong>in</strong>ation of ion pairs take place. Region II is the ionization chamber<br />

region. No recomb<strong>in</strong>ation of ion pairs takes place here, and no secondary electrons are<br />

produced. Region III is the region of proportionality. The number of secondary ion pairs<br />

produced is directly proportional to the number of primary ion pairs produced. Region<br />

IV is the region of limited proportionality. Region VI is the region of cont<strong>in</strong>uous<br />

discharge. A represents voltage levels that produce simple ionization. For the voltage<br />

levels B, multiplication of primary ionization takes place.<br />

2.4.1.1. Ionization chambers<br />

Ionization chambers are used as survey meters, as dose calibrators, and as standard<br />

measur<strong>in</strong>g devices for determ<strong>in</strong><strong>in</strong>g radiation levels. They are useful because they can<br />

<strong>in</strong>dicate the quantity of <strong>in</strong>com<strong>in</strong>g radiation and <strong>in</strong> some cases its energy as well. This<br />

capability enables the user to identify the source as well as the strength of radiation<br />

present as <strong>in</strong> the case of a radionuclide, or to calibrate the beam quality and quantity of an<br />

X‐ray generator.<br />

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