Grid Computing in High Energy Physics Experiments
Dagmar Adamov, Pablo Sáiz · InTech eBooks · 2012
Will-be-set-by-IN-TECH"forward particles".These are particles that just brush past each other as the beams collide, rather than meeting head-on.The energy of the protons is currently 3.5 TeV (1 Tera eV= 1 million MeV) and that of the Pb ions is 1.38 TeV, so the collision energies are 7 TeV for the protons and 2.76 TeV for the Pb ions.The phrase often used to summarize the mission of the LHC is, that with the LHC we are going back in time very close to the Big Bang, as close as about 10 -10 seconds.In terms of length it represents about 10 -16 cm (compared to the dimensions of the Universe of about 10 28 cm).At this scale, the matter existed in a form of a "soup" made of the quarks and gluons, the Quark Gluon Plasma.The quarks are objects protons and neutrons are made of, so the LHC represents in a sense a huge extremely complicated microscope enabling the study of the most basic elements of matter.There are several major questions which scientists hope to get answered with the help of the LHC.• What is the origin of mass, why do elementary particles have some weight?And why do some particles have no mass at all?At present, we have no established answers to these questions.The theory offering a widely accepted explanation, the Standard Model [11], assumes the existence of a so-called Higgs boson, a key particle undiscovered so far, although it was first hypothesized in 1964.One of the basic tasks of the LHC is to bring an established statement concerning the existence of the Higgs boson.• Where did all the anti-matter disappear?We are living in the World where everything is made of matter.We suppose that at the start of the Universe, equal amounts of matter and antimatter were produced in the Big Bang.But during the early stages of the Universe, an un-known deviation or in-equilibrium must have happened, resulting in the fact that in our world today hardly any antimatter is left.• What are the basic properties of the Quark-Gluon Plasma, the state of the matter existing for a tiny period of time after the Big Bang?Originally, we thought it would behave like a plasma, but the latest scientific results including those delivered by the LHC suggest that it behaves like a perfect liquid [2], which is somewhat surprising for us.• What is the universe made of?At the moment, the particles that we understand create only 4 % of the universe.The rest is believed to be made out of dark matter and dark energy.The LHC experiments will look for supersymmetric particles, which would confirm a likely hypothesis for the creation of dark matter.From the experiments analyzing the data from the LHC collisions, ATLAS and CMS are the largest.They were nominally designed to look for the Higgs boson but in fact these are general purpose detectors for the study of all kinds of Physics phenomena at the LHC energy range.The ALICE detector is a dedicated heavy ions detector to study the properties of the Quark Gluon Plasma formed in the collisions of lead ions at the LHC energies.The LHCb is much smaller detector and its mission is to study the asymmetry between matter and antimatter.Although all these experiments are designed for Particle Physics research, the scientific programs they follow actually cross a border between Particle Physics, Astrophysics and Cosmology.Now, where does the Computing Grid show up in this scientific set-up?The LHC is the world's largest particle accelerator.The protons and lead ions are injected into the accelerator 182 Grid Computing -Technology and Applications, Widespread Coverage and New Horizons www.intechopen.com