The ATLAS detector at the LHC

The LHC accelerator at CERN has started operation in Winter 2009, with proton beams colliding at an unprecedented center of mass energy of 7 TeV. The ATLAS detector, which will exploit the physics potential of this new research facility, is fully commissioned and operational. The ATLAS project represents the effort of a large fraction of the high-energy physics community worldwide, to integrate modern detection technology into a very complex environment. ATLAS is a 7000 tons magnetic device counting more than 80 million active channels, operating at a 40 MHz readout frequency. The detector is performing according to its design parameters and is showing excellent performance. The variety of technologies used represents an important test bench for many future applications in several domains of hardware and software technology.