A PROTOTYPE SILICON PRERADIATOR FOR THE SSC

We describe the design and first results from the test of a prototype of a preradiator detector. Such a detector could be used to enhance the identification of photons and electrons at the Superconducting Super Collider (SSC). Specifically, it may be used by the GEM detector to distinguish between single photons from Higgs decay and background photon pairs from pi0 decay. Our prototype consists of tungsten radiator followed by silicon strip detectors. The tungsten thickness was changeable, varying from 0 to 3 radiation lengths. Two silicon detectors, oriented in X and Y, consist of 48 strips, each of length 48mm. The pitch is 1mm. This granularity is required for separating single and multi-photons at the SSC. The readout is achieved by low-noise, low-power custom preamplifier chips mounted directly on the detectors via custom circuit boards. This preradiator was tested in a beam at Brookhaven (BNL) in July 1992. A lead glass array placed behind the silicon was used to determine energy resolution effects. The results from the test on spatial distributions and energy resolution, including correction for the energy deposited in the preradiator are presented, along with comparisons to EGS simulations.