The Future of Silicon in High Energy Physics
The last barrier to the wide use of silicon microstrip sensors was overcome when a CERN-Hawaii-Stanford collaboration, started by Bernard Hyams of CERN, made the world's first VLSI readout chip, replacing the large fanout boards and massive cable bundles then required. Now we face a new problem:Present silicon microstrip sensors, with their fabricated elements confined to near-surface regions, will not survive the radiation in the innermost regions of LHC detectors such as Atlas. Sensors using a new architecture in which narrow electrodes penetrate through the three dimensional volume of the silicon substrate, have been fabricated, tested with radioactive sources, and exposed to an intense proton beam. They easily survive more damage than is expected for 10 years at that innermost radius.
This was made possible by a new technology - micromachining - that has grown out of, and has extended VLSI fabrication methods. The next change, now underway, will be for sensor arrays customized for x-ray beam lines where protein shapes are measured in the effort to learn how proteins work.