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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.