Two circulating beams bring first collisions as experiments are re-started at the Large Hadron Collider at CERN

Re-creating the ‘Big Bang’ to understand how the universe evolved

24/11/09: On 23 November 2009 the LHC circulated two beams simultaneously for the first time, allowing the operators to test the synchronization of the beams and giving the experiments their first chance to look for proton-proton collisions.

Following its closure at the end of last year the LHC is now in its 4th day of operation. Since the start-up, the operators have been circulating beams around the ring alternately in one direction and then the other at the injection energy of 450 GeV. The beam lifetime has gradually been increased to 10 hours, and have have been circulating simultaneously in both directions, still at the injection energy.

As the world’s most powerful particle accelerator, the Large Hadron Collider (LHC) at CERN in Switzerland produces an enormous data deluge of 15 petabytes per year (15 million Gbit/s) with JANET contributing to the worldwide distribution of the data for analysis.

The huge amounts of data generated by the experiments, is distributed among a number of collaborating organisations via the LHC Computing Grid (LCG). Ffrom CERN, data is transferred to 11 Tier 1 sites across North America, Asia and Europe. The data is then distributed to 140 regional Tier 2 sites based around the world; these are typically at universities or major national laboratories.

The Rutherford Appleton Laboratory (RAL) at Harwell in Oxfordshire is one of the Tier 1 sites and provides 10% of the UK’s contribution. Data is carried end to end on a dedicated lightpath from CERN to RAL using the GEANT and JANET networks. During the summer, JANET worked with the tier 1 and 2 sites for STEP’09, the first full demonstration involving all the key elements from data taking at CERN through to analysis of data at the individual sites worldwide.

“The tracks we’re seeing are beautiful,” said LHCb spokesperson Andrei Golutvin, “we’re all ready for serious data taking in a few days time.”

Next on the schedule is an intense commissioning phase aimed at increasing the beam intensity and accelerating the beams. All being well, by Christmas, the LHC should reach 1.2 TeV per beam, and have provided good quantities of collision data for the experiments’ calibrations.

For fiurther details and updates, please go to the CERN website: http://www.cern.ch