Analysis of CdTe as a γ‐Ray Spectrometer

Gamma spectra were taken at room temperature with devices fabricated from semi‐insulating CdTe. A resolution of 8 keV (FWHM) was found for 241Am (60 keV), 10 keV for 57Co (122 keV), 30 keV for 137Cs (662 keV), and 75 keV for 60Co (1.33 MeV). The photoelectric absorption coefficient at a photon energy of 122 keV was measured to be 5.4 ± 0.4 cm−1 in CdTe. The escape of the photoelectron at higher photon energies degraded the spectra and lowered the absorption coefficients below their theoretical values. Devices were also encapsulated within probes and their efficiency to photoelectric events was compared with that of a silicon detector. Ratios of 150:1 for 57Co and 12:1 for 241Am were found favoring CdTe.