The Silicon Shower Maximum Detector For the Stic

The structure of a shashlik calorimeter allows the insertion of tracking detectors within the longitudinal sampling to improve the accuracy in the determination of the direction of the showering particle and the e/pi separation ability. The new forward calorimeter of the DELPHI detector has been equipped with two planes of silicon pad detectors respectively after 4 and 7.4 radiation lengths. The novelty of these silicon detectors is that to cope with the shashlik readout fibers, they had to incorporate 1.4 mm holes every cm(2). The detector consists of circular strips with a radial pitch of 1.7 mm and an angular granularity of 22.5 degrees, read out by means of the MX4 preamplifier. The preamplifier is located at 35 cm from the silicon detector and the signal is carried by Kapton cables bonded to the detector. The matching to the MX4 input pitch of 44 mu m was made by a specially developed fanin hybrid.