Progress in the ALICE silicon pixel detector

The ALICE silicon pixel detector comprises two barrel layers with ≈107 hybrid pixel cells. The basic detector element is a half-stave, an array of two ladders, each consisting of 5 pixel chips bump bonded to a Si sensor matrix. The ladders are mounted on a low-mass aluminium/polyimide multilayer bus for power distribution and signal routing. Each half-stave is controlled and read out via a multi-chip-module. All chips are ASICs in CMOS 0.25 μm technology with radiation hard design. Data transfer is done on optical fibres. The system and recent progress in its implementation are overviewed.