Analysis of CdTe as a γ-Ray Spectrometer

Abstract

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.