ATLAS is a particle physics experiment at the Large Hadron Collider (LHC) at CERN, and is one of two general-purpose detectors at the LHC. The ATLAS detector will search for new discoveries in the collisions of protons of unprecedented high energy. ATLAS will learn about the basic forces that have shaped our Universe since the beginning of time and that will determine its fate. Among the possible unknowns are the origin of mass, extra dimensions of space, microscopic black holes, and evidence for dark matter in the Universe.
The ATLAS experiment plans two stages of upgrades which encompass a number of detector, trigger, software and computing developments that will be required to continue the exploitation of ATLAS throughout and beyond the next decade. Upgrades are required to cope with the anticipated increase in the beam luminosity: a Phase I increase to 3 x 1034 cm-2 s-1 (3 times design luminosity) by around 2015, followed by Phase II (the sLHC) bringing an increase to 10 x 1034 cm-2 s-1 (10 times design luminosity) around 2020.
The principal areas of UK involvement in the upgrade R&D centre on providing a successor to the current Semiconductor Tracker (SCT), which has a radiation-dictated lifetime finishing towards the end of the coming decade. In addition, triggers and computing infrastructure must be able to cope with an order of magnitude more luminosity than the current design. These developments all build on the track record the UK established in these areas in the construction of the current detector.
The UK groups make up about 10% of the international ATLAS collaboration. The upgrade will roughly maintain this level of involvement in the upgrade in order to deliver key parts of the detector upgrade and maintain current levels of leadership.