First results from the integration tests of the ALICE silicon pixel detector

Full text: The ALICE silicon pixel detector constitutes the two innermost layers of the ALICE inner tracking system. It consists of two barrel layers located at radii of 3.9 cm and 7.6 cm. The inner and outer layer cover a range in pseudorapidity of |n| = 1.9 and 1.4, respectively. The two barrels are divided into 10 sectors, each containing 12 modules (half-staves). On every sector four half-staves are mounted on the inner and eight halfstaves to form the outer barrel. The whole SPD contains 1200 mixed signal ASICs in radiation hardened design in 0.25 μm CMOS with a total of 9.8 million pixel cells. All communication (data, control, clock) with the off-detector electronics is carried out via bidirectional optical links. An evaporative cooling system with C4F10 is used to remove the 1.5 kW dissipated power from the SPD. The material budget limitations required a careful design of all components of the SPD in order to achieve a total material budget per layer of 1 % X0. The integration tests of the SPD sectors and the assembled half-barrels have been carried out in a clean room at CERN. All tests were performed with the full readout electronic chain, the final power supplies and cables and the cooling plant as it will be used in the ALICE experiment. The test setup and results of the integration test of the SPD are presented. (author)