Development of a 128 channel silicon drift detector for spectroscopic purposes

A linear silicon drift detector with an active area of 1.28 x 2.56 cm² has been designed. On each short side of the detector a row of 64 anodes is placed. The detector is intended for X-ray fluorescence purposes. Position resolution is obtained only from the anode number and not from drift time. Energy resolution is important and lateral charge diffusion to neighboring anodes cannot be tolerated. In this work minimization of the lateral charge diffusion by a sawtooth shape of the cathode biasing strips is studied. The main advantage of this method is that additional processing steps are not required. We measured ⁵⁵Fe spectra using a small detector in which the influence of lateral diffusion was still present. For the 128 anode detector of the right size we report charge collection over the maximum drift distance of 1.28 cm. Unfortunately this specific detector did not allow the extraction of diffusion data.