Performance of double-sided CdTe strip detectors for gamma-ray imaging and spectroscopy

We developed double-sided CdTe strip detectors and studied their performances. By readout from both anode and cathode strips, a double-sided CdTe strip detector can achieve large area and high position resolution with a small number of readout channels. Therefore it is very attractive for gamma-ray imaging and spectroscopy. We developed double-sided CdTe strip detectors with Al/CdTe/Pt electrode configulation. The detectors have a size of 1.28 cm × 1.28 cm and a thickness of 0.5 mm and 2.0 mm. Both electrodes are divided into orthogonal 32 strips surrounded by guard-ring electrodes. The strip pitch is 400 μm. We successfully operated the detectors at a temperature of −20 °C and a bias voltage of 500 V, and obtained spectra of gamma-ray from radio isotope sources. By using the detector with a thickness of 0.5 mm, energy resolutions of 1.8 keV (FWHM) for 60 keV gamma-ray was obtained from each side. From both signals from anode and cathode for each photons, we successfully reconstructed incident photon energy, and obtained energy resolutions (FWHM) of 1.5 keV for 60 keV. By using the detector with a thickness of 2.0 mm, the energy resolution of 8.0 keV (FWHM) for 662 keV was obtained by anode signals. We successfully estimated incident photon energy from the relation anode and cathode signals, and we achieved the energy resolution of 6.2 keV (FWHM) for 662 keV.