How efficient is a beta-gamma survey meter in detecting gamma radiation?

A beta-gamma survey meter is specifically designed to detect both beta and gamma radiation, but it operates with varying efficiencies depending on the type of radiation being measured. When it comes to gamma radiation, the efficiency of a beta-gamma survey meter is generally quite low, often less than a few percent. This low efficiency is due to the fact that the detector is primarily optimized for detecting beta particles rather than gamma photons.

Gamma radiation can penetrate materials more effectively than beta radiation; thus, these meters often have materials that attenuate the gamma rays significantly before they are detected. This results in a reduced probability of interaction with the detector for gamma radiation compared to beta radiation.

In this context, recognizing that a beta-gamma survey meter's efficiency for gamma detection is less than a few percent aligns with the general understanding of the performance characteristics of these instruments. This reflects the inherent limitations in detecting gamma rays effectively with a meter that is not primarily designed for that purpose.