Priscilla B. Cushman and Adriaan H. Heering

"CMS HCAL Hybrid Photodiode Design and Quality Assurance Stations"

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The hadronic calorimeter for the CMS experiment requires photodetection in a 4 Tesla magnetic field. This, plus high neutron radiation and a 25 ns bunch-crossing, necessitated the development of a new type of high-rate multi-channel hybrid photodiode. As our specifications became tighter, design changes in the diode structure and surface treatment became necessary, resulting in a better product with very low crosstalk in both AC and DC modes. The specifications are rigorous and are maintained by a set of automated Quality Assurance stations which will process 570 tubes over 2 years.

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Last modified: 17 June 2002, J. Schwiening.