Close-up of a silicon "microscope"
10 March 1999
Look at the right-hand side of this image and you should see more clearly the horizontal strips of tiny particle detectors fabricated on a piece of silicon wafer. These "microstrips", only 25 microns apart, pick up electrons and "holes" liberated in the silicon when a charged particle passes through. The strip nearest the particle's path will pick up the biggest signal and so reveal the location of the particle's track to high precision. This particular silicon strip detector forms part of the "vertex detector" of the DELPHI experiment at CERN, the European Laboratory for Particle Physics. The vertex detector is like a "microscope" to provide precise measurements - to within 10 microns - of particle tracks close to the point at the heart of DELPHI where electrons and positrons collide.
Credit: Physics Photographic Unit, University of Oxford
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