Development of a large area silicon pad detector for the identification of cosmic ions

A silicon sensor with 64 large area pads (“pad” of 1 cm2 area) was developed to identify relativistic ions in direct measurements of the elemental composition of cosmic rays. A single-element discrimination can be achieved via an accurate measurement of the electric charge Z, taking advantage of the Z2 dependence of specific ionization in silicon. Space-based or balloon-borne cosmic ray experiments of the next generation require the coverage of large sensitive areas with arrays of this kind of detectors. Preliminary results on the performance of the sensor are presented.