ATLAS detector. Composite image of the ATLAS (a torodial LHC apparatus) detector (circular) at CERN (the European particle physics laboratory) near Geneva, Switzerland. The detector will be placed around the large hadron collider (LHC), CERN's highest energy particle accelerator. A computer representation of the proton beams that will flow through the LHC has been added to the photograph. ATLAS is a general- purpose detector designed to measure the broadest possible range of particles and physical processes that could result from the collision of the proton beams at very high energies. A pilot run of the LHC is scheduled for summer 2007.