Detector modules for the endcaps of the ATLAS semiconductor tracker

The endcaps of the ATLAS Semiconductor Tracker will be composed of about 2000 detector modules of three different layouts. Up to four single-sided sensors are glued back-to-back with a small stereo angle to form double-sided modules. Five different wedge shaped sensor designs are needed, with a strip pitch varying in the range from 55 to 95 mu m. The sensors are read out by a copper/Kapton multilayer hybrid which carries 12 binary read-out ASICs and all components for the optical transmission of commands and data. Within the tight constraints imposed by the need for radiation hardness, high rate capability, low mass, low cost and overlap between neighbouring modules for detector hermiticity the design has been optimised for a thermal split between the read-out chips and the silicon sensors. The performance of prototype modules stand-alone, in multi-module system tests and in the testbeam will be shown. (9 refs).