Clean work on silicon ladders for CLEO III

15 December 1999



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Last week's image showed the heavy civil engineering side of preparing experiments for particle physics. This week shows preparatory work in the completely contrasting environment of a clean room. The detector seen here under construction is called Si3 and is to be part of the CLEO III experiment at the Cornell Electron Storage Ring (CESR), Ithaca, New York. In its final form, completed in November 1999, Si3 contains 450,000 silicon strips, each about the width of a human hair. The strips are fabricated on silicon wafers, which are assembled into the "ladders" of several wafers which are seen here. The ladders are arranged in four concentric cylinders and held in place at each end by a framework of synthetic diamond and copper. In this week's picture members of the Si3 team at Purdue University - technician Tom Smith, physicist Ian Shipsey and mechanical engineer Kirk Arndt, (left to right) - are at work on the delicate task of putting Si3 together. CLEO III will study the decays of b quarks and antiquarks, produced in the annihilations of electrons and positrons in the CESR machine. The aim is to investigate tiny differences between matter and antimatter, in an effort to understand the preponderance of matter over antimatter in the Universe.

Credit: Purdue University