Occupational Safety and Health Administration OSHA

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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