Characterization of thin back-to-back CdTe detectors

Thin CdTe detectors (3×5 mm² electrode area, 0.5 and 0.8 mm thick), mounted in back-to-back configuration with common anode have been characterized. This configuration allows one to double the useful absorbing thickness in the classical planar parallel field (PPF) irradiation geometry and to double the sensitive area in the planar transverse field (PTF) geometry, while maintaining the same interelectrode distance (0.5 or 0.8 mm) and one electronic chain as for single detectors. The tests performed aim at understanding the effects on the spectroscopic performance of various interelectrode distances and in particular of the chemical and mechanical treatments used to make thin detectors. A narrow photon beam, 10-150 keV in energy, obtained using a 20-mm-thick tungsten collimator, was employed. The results obtained, compared with previous measurements on various thicknesses devices, indicate that the optimum single detector thickness is 1 mm