Performance of CdTe, HPGe and NaI(Tl) detectors for radioactivity measurements

The characteristics and performances of the NIST High-Purity Germanium (HPGe), Sodium Iodide (NaI(Tl)) and Cadmium Telluride (CdTe) gamma-ray detectors were studied. The efficiencies, the minimum detectable activities and the energy resolutions of each were measured and compared. The data were analyzed using different software packages. The measurements were performed in a low background radiation environment using calibrated point sources. The CdTe detector showed a higher energy resolution than the NaI(Tl) detector but a lower efficiency than both the HPGe and NaI(Tl) detectors. This makes it a suitable detector only for relatively high activity measurements restricted to the 35 keV to 200 keV energy range.