CHARACTERIZATION OF SMALL CDTE DETECTORS TO BE USED FOR LINEAR AND MATRIX ARRAYS

There is growing interest in semiconductor X- and gamma ray detectors constructed from CdTe crystals, mainly for use in applied research and in the medical and industrial fields. For a better understanding of the performances of these detectors, we have investigated two different operative modes. The first one, named the 'type A' solution, has the direction of the bias electric field parallel to the direction of the impinging radiation; the second one, named the 'type B' solution, has the bias electric field perpendicular to this direction. Most work has been devoted to the type B solution which allows the assembly of linear and rectangular (or square) detector arrays with good spatial resolution and with excellent efficiency even for photons of rather high energy (around 500 keV). In the present work two energy spectra and one time spectrum are shown from a 2.5x2.5x20 mm3 type B detector. Furthermore, a square matrix of 5x5 detectors (2x2x10 mm3 each) is described which constitutes an array for studying experimentally the influence of the radiation scattered from one detector into those surrounding it. For the moment, however, this cross-talk interaction has been simulated by a three dimensional Monte Carlo code.