| 18 Particle Physics at LHC/CMS 4 Particle Physics at LHC/CMS (2007) | |||||||||||||
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| and the CMS collaboration. In 1995 the Physik-Institut of the University of Zurich joined the CMS collaboration at the Large Hadron Collider. We participate (i) in the development and construction of the barrel silicon pixel detector (design of the pixels and readout chips and construction of the support structure and cooling system) and (ii) in the design and development of microstrip gas chambers (MSGC). 4.1 Pixel developments The CMS pixel detector consists of two forward detectors and a barrel detector. The forward detectors are under the responsibility of the U.S. groups. According to the current layout [1] the barrel detector is made of three cylindrical layers, 53 cm long with radii of 4, 7 and 11 cm. The support structures are made of tubes with trapezoidal cross sections (providing water cooling) connected with carbon fibre blades and supported at both ends by carbon fibre end rings. Each layer is made of two half-cylinders to allow insertion into the CMS detector. Due to radiation damages close to the interaction point which limit the lifetime of the detectors, the two innermost layers will be used in the beginning during low luminosity run. The two outermost layers will be used during full luminosity runs and we anticipate that the 7 cm radius detector will have to be replaced after 5 years of LHC running. A pixel cell contains 53 \Theta 52 pixels of dimensions 150 \Theta 150 m 2. Two rows of 8 cells build a module and a row of 8 modules builds a facet of length 53 cm and width 1.75 cm. The total number of pixels to be read out are 6.3 \Theta 10 | |||||||||||||
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