A schematic view of the setup of the ALICE experiment is shown on the left hand side (click image for an enlarged view). The red structure is a large magnet enclosing a number of detector layers, which surround the interaction point, where the two beams of the accelerator will meet. The tracking and momentum measurement of charged particles is performed with the help of the Time Projection Chamber (TPC, the hollow structure indicated in grey) and the Inner Tracking System (ITS, in the center of the TPC).
The ITS (picture on the right) consists of six layers of highly granular silicon detectors using different technologies: a silicon pixel detector, a silicon drift detector and a silicon strip detector (SSD). The SSD forms the outer two layers of the ITS.
The SSD consists of 72 carbon-fibre ladders with 22 or 25 detector modules each. The modules contain the double-sided silicon sensors with 2 x 768 strips and the corresponding front-end electronics mounted on extremely thin cables. The detector consists in total of about 2.6 million individual channels.
The signals are read out via endcap electronics (designed and constructed at NIKHEF) to the FrontEnd-Read-Out-Modules (FEROM, designed and constructed at the university). The ladders with the water cooling system are mounted on a carbon fibre cylinder. (See left hand side for a schematic view of the SSD.)
The top figure in the right column shows a view of the full SSD in the final construction phase at the university. The golden bands are the ladder cables transporting the detector signals to the endcap electronics.
The figure in the right column below the full SSD shows a single SSD module with cables attached in an unfolded state. In the detector, the thin cables with the front-end electronics are folded onto the wafer to make the module as compact as possible.