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Radiation Detection Instruments

Instrument Types Detection Principle Applications

Ion chamber (IC)

Ionization of air
(or other gases)

Direct measurement of exposure or exposure rates, with minimal energy dependence.

Geiger-Mueller (GM)
Proportional counter (PC)

Ionization of gas with
multiplication of
electrons in detector

Detection of individual events, i.e. alpha or beta particles & secondary electrons, for measuring activity (in samples or on surfaces) & detecting low intensities of ambient x or gamma radiation; precautions required due to energy dependence.

Solid state diodes

Ionization of

Detection & energy measurement of photons or particles; primarily for laboratory use.

Solid state diodes

Ionization & excitation
followed by light emission

Detection of individual events;



- NaI (Tl) - photons; energy spectrometry


- ZnS (Ag) - alpha particles; detection only



- Detection of low-energy beta emitters mixed with the scintillation fluid.

Photographic film

Ionization of Ag Br

Personal exposure monitoring.

Thermoluminescent detector (TLD)

Excitation of crystal;
light release by heating

Personal and environmental exposure monitoring.

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