Study of a CdTe multipixel spectrometer for X- and γ-rays

The performance of a prototype CdTe linear multipixel detector in the arrangement with the collecting field orthogonal to the incoming radiation (PTF configuration) is reported. This detector was conceived to be employed as the basic element to realise both two-dimensional and linear position sensitive spectrometers with a large number of pixels for hard X- and soft γ-rays. The prototype has been produced from a single CdTe crystal of 10 × 10 × 2 mm3 using strips technology and is geometrically equivalent to a linear array of five microdetectors of 2 × 2 × 10 mm3 with the electrodes deposited on the 2 × 10 mm2 sides. The active area of each pixel is about 2 × 2 mm2. After the electrical characterisation of the detector, several tests have been performed by radiating the detector with standard sources. Scanning the detector with a 57Co source over the pixels has shown the uniformity of spatial response and has allowed the measurement of the spatial resolution of the array. In order to evaluate the spectroscopic capability further tests using sources with energy between 10 and ∼400 keV, moved along the anode-cathode direction, have been performed. The first results have demonstrated that the multipixel CdTe crystal acts as a linear position sensitive spectrometer made of 5 PTF microcrystal at least up to a few hundreds keV.