Which survey instrument is best for detecting alpha contamination?

The Geiger-Mueller (GM) detector with a thin window is particularly effective for detecting alpha contamination due to its design that allows alpha particles, which are relatively large and have low penetration power, to enter the detection chamber. Alpha particles can be stopped by even a sheet of paper or the outer layer of human skin; therefore, a thin window is necessary to facilitate the detection of these particles by not obstructing their entry into the detector.

When using a GM detector with a thin window, the likelihood of detecting alpha particles increases significantly compared to a thick window arrangement, which would absorb or deflect these particles before they can initiate a detection response. This capability makes this specific type of GM detector suitable for measuring alpha radiation from contamination sources effectively.

In contrast, other survey instruments may not be as adept at detecting alpha radiation. For example, an ionization chamber functions primarily for measuring higher energy radiation like beta and gamma radiation rather than low-energy alpha particles. Scintillation detectors are versatile and can detect a variety of radiation types, but unless specifically designed for alpha detection, their efficiency can be compromised due to the same reasons that affect GM detectors with thick windows. Therefore, the choice of the GM detector with a thin window is optimal for detecting alpha contamination