The sensors are grouped in pairs to make a total of 42 modules, arranged in two halves around the beam line in the VELO vacuum tank. An aluminum sheet just 0.3 mm thick provides a shield between the silicon modules and the primary beam vacuum, with no more than 1 mm of leeway to the silicon modules. Custom-made bellows enable the VELO to retract from its normal position of just 5 mm from the beam line, to a distance of 35 mm. This flexibility is crucial during the commissioning of the beam as it travels round the 27-km ring of the LHC.
Press releases November 2007
Geneva, 7 November 2007. At a brief ceremony deep under the French countryside today, CERN1 Director General Robert Aymar sealed the last interconnect between the main magnet systems in the Large Hadron Collider (LHC). This is the latest milestone in commissioning the LHC, the world’s most powerful particle accelerator.