The basic idea of Grid Computing is to utilize available CPU cycles and storage of many computer systems across a worldwide network so that they can function as a flexible, pervasive, and inexpensive accessible pool that could be harnessed by an individual, accredited user, similar to the way power companies and their users share the electrical grid. Grid computing can be viewed as a service for sharing computer power and data storage capacity over the Internet, simply and transparently, without having to consider where the computational facilities are located.
Experiments at major centralized experimental facilities such as the Large Hadron Collider (LHC) require large amounts of computation and storage and involve hundreds of experimenters using computational facilities all over the world. These features are well suited to the capabilities of grid computing. Grid computing developments occurred in parallel to the development of the LHC experiments. The Open Science Grid (OSG) is the major facilitator of Grid Computing in the U.S. Researchers subsequently developed these ideas in many other exciting ways, producing for example, in addition to OSG, large-scale federated systems (TeraGrid, EGEE, Earth System Grid) that provide not just computing power, but also data and software on demand. Standards organizations then developed relevant standards that led to possible interoperability of Grids. Grids define and provide a set of standard protocols, middleware, toolkits, and services built on top of these protocols. Interoperability and security are the primary concerns for the Grid infrastructure as resources may come from different administrative domains, which have both global and local usage policies, different hardware and software configurations and platforms, and vary in availability and capacity.
The Open Science Grid is a distributed computing infrastructure for large-scale scientific research. The OSG contributes to the Worldwide LHC Computing Grid as the shared distributed computing facility used by the US ATLAS and US CMS experiments. The OSG is built and operated by a consortium of 90 U.S. universities, national laboratories, scientific collaborations and software developers. It is supported by the National Science Foundation and the US Department of Energy Office of Science. The OSG supports not only physics experiments but also researchers from other fields, including astrophysics, bioinformatics and computer science. Currently the OSG has more than 60 sites in the US and five sites in Brazil, Taiwan and Mexico, supported by the host countries.
All LHC computing and storage sites in the US are members of the OSG and allow other scientific collaborations using the OSG to opportunistically use available resources. The OSG collaborates with the Enabling Grids for E-sciencE project in Europe to provide interoperating federated infrastructures which can be used transparently by the LHC experiments' software. The Large Hadron Collider, located 330 feet below the border of Switzer¬land and France, is the world's most powerful particle accelerator. Its very-high-energy particle collisions may yield extraordinary discoveries about the nature of the physical universe. Beyond revealing a new world of unknown particles, the LHC experiments could explain why those particles exist and behave as they do. The LHC experiments could uncover the origins of mass, shed light on dark matter, expose hidden symmetries of the universe, and possibly find extra dimensions of space.
The LHC accelerates hair-thin beams of particles to a whisker below the speed of light. Thousands of powerful superconducting magnets steer the beams around the LHC's 16.5-mile-long ring. At four points the particles collide in the hearts of the main experiments, known by their acronyms: ALICE, ATLAS, CMS and LHCb. In the data from these high-energy collisions scientists search for the tracks of particles whose existence could transform our understanding of the universe. More than 10,000 scientists, engineers and students from almost 60 nations on six continents contribute to the LHC, which is headquartered at the CERN laboratory in Geneva, Switzerland. About 1,700 come from universities and laboratories in the United States. Federal funding for US contributions to the LHC is provided by the US Department of Energy's Office of Science and the National Science Foundation.
