The Model 44-2 is a 1" X 1" NaI(Tl) Gamma Scintillator that can be used with several different instruments including survey meters, scalers, ratemeters, and alarm.

The Model 44-3 is a 1" X 1mm NaI(Tl) Gamma Scintillator for low energy gamma that can be used with several different instruments including survey meters, scalers, ratemeters, and alarm ratemeters.

For that, you need something like this gamma-ray spectroscope ... cesium iodide crystal and a silicon photomultiplier. The scintillator is potted in silicone in a 3D printed enclosure, to protect ...