The SCT system is designed to provide eight precision measurements per track in the intermediate radial range, contributing to the measurement of momentum, impact parameter and vertex position. In the barrel SCT eight layers of silicon microstrip detectors provide precision point in the r-f and z coordinates, using small angle stereo to obtain the z-measurement. Each silicon detector is 6.36 x 6.40 cm©Õ with 780 readout strips of 80 µm pitch. The barrel modules are mounted on carbon-fibre cylinders at radii of 30.0, 37.3, 44.7, and 52.0 cm. The end-cap modules are very similar in construction but use tapered strips with one set aligned radially. The SCT covers a pseudorapidity-range < 2.5.

SCT barrel (left) and outer (right) modules in system test.

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