Authorized users shall make sure that instruments operate correctly and are maintained in a serviceable condition. It is important to select an instrument that is appropriate for the radionuclides used. Ion chambers, which measure exposure rate, are useful in certain applications. Both types operate on the same principle, but the pancake detector usually has higher counting efficiencies. GM detectors are not recommended for measuring gamma contamination in the laboratory.
Scintillation detectors are superior for that purpose.
Consult your instrument manual for your instrument's unique energy-response curve. When performing surveys or entering areas where significant exposure rates or contamination are suspected, always approach the area cautiously with the survey meter turned on. A rapid increase in count rate followed by a drop to zero indicates a high radiation field. Perform surveys slowly enough to detect small changes in count rates. Pancake detectors have about twice the counting efficiency for beta emitters than end-window detectors.