Silicon Drift Chamber

  A detector based on wafers of semiconductors and aiming to obtain the two-dimensional capabilities and the resolution of the pixel detector, but circumventing the problem of the large number of channels. This detector essentially consists of a fully depleted thin semiconductor wafer, with a linear arrangement of anodes at the edge (or on two edges opposite each other), and a cathode at the opposite edge (or in the middle). An electric field makes the electrons, generated by a passing charged particle, drift towards the array of anodes, at a moderate speed (like 15 mm/ s), thus obtaining two coordinates in the plane of the wafer: the anode position along the edge, and the drift time converted to distance perpendicular to the edge. The drift length is limited by the size of the wafer (a few centimetres), the anode pitch is chosen to be submillimetre, and a resolution of   can be achieved (charge division between anodes can improve the precision). Early references are [Gatti88] and [Gatti84], more recent ones are [Vacchi93] or the specialized meeting proceedings [Holl96].