Strip detector for short-range particles

A silicon strip detector for the coordinate determination of short-range charged particles, particularly heavy ions, has been developed. The detector has 28 p⁺n strips made by ion implantation. The pitch is 250 μm, and the interstrip distance is 50 μm. The coordinates of particles incident between adjacent strips are determined by two-dimensional amplitude analysis of the charges collected on neighboring strips. Irradiation with α-particles of ²²⁶Ra and a scanning laser beam was used. A coordinate determination accuracy of better than 1 μm was obtained. In contrast to the minimum ionized particle, the plasma tracks of short-range particles have higher carrier densities and were located in the inhomogeneity region of the detector. The study of the charge collection times has clarified the essential role of the drift of charges in an inhomogeneous electrical field, dependent on the detector geometry, and the inhomogeneity of silicon and built-in charge in passivating the oxide layer between the p⁺n strips