Multielement CdTe stack detectors for gamma-ray spectroscopy

This paper describes the development of a field portable γ-ray spectroscopy system based on multielement CdTe detectors. A stack of multiple planar detector elements is used, with each individual element thin enough for good charge transport and outputs summed so that the full volume is used. The detector elements are CdTe diodes mounted on a thermoelectric cooler, providing low noise and good charge transport with relatively simple electronics. Current devices have a volume of 5 mm ×5 mm ×2.25 mm, with an energy resolution of 1.5 (4.5) keV full-width at half-maximum (FWHM) at 122 (662) keV. These operate as simple planar devices, with no corrections or complex electronics. We anticipate achieving a resolution of <1% FWHM at 662 keV with a volume of at least 0.5 cm³ and that the approach will be suitable for production. To optimize the detector configuration, simulation software was developed and test devices fabricated. This paper will present simulation results and experimental data obtained using multielement detectors.