Summary

• All radiation measuring instruments  have a detector in which the radiation deposits energy. The detector has to respond in a reproducible manner.
• Ionisation chambers  measure the ionisation   produced by the radiation in a gas filled volume. They can be used in dose rate instruments (gamma or beta survey), or as dosimeters  which indicate total dose received (DRDs) 
• Proportional counters  can be designed to distinguish between radiation types.
• Geiger counters  produce the same size output pulse regardless of how many ion pairs  were created in the detector. They are well suited to the detection of contamination, but can be designed to measure gamma dose rate as well.
• An instrument must identify the type of radiation it detects. This can be achieved by detector design, electronic design or by using special operating techniques.
• Scintillation detectors  are used with pulse height analyzers  to identify gamma emitting radionuclides . They are also used in portal monitors , thyroid monitors , and tritium bioassay .
• TLDs  measure absorbed dose. They are the official dosimeter for dose record purposes for external gamma and beta radiation  .