LHC Reaches Half Energy of Proton Beams

March 18, 2010 (HE42).  This night the CERN flagship accelerator, the LHC,  has accelerated counter-circulating proton beams at 3.5 TeV per beam. The magnet system has performed very well as did its cryogenic system working at superfluid helium. The total stored energy was about 2.5 GJ. The ramp up to half field (3.5 TeV of beam energy corresponds to a magnetic field of the dipole of about 4.15 T) has been carried out without significant beam losses, showing the very good field model and accuracy of the magnets.

The LHC was stopped after the serious incident of 19 September 2008, and it was restarted in November 2009, to reach record collision energy of 2x1.18 TeV in December 2009. After a technical stop of two months to improve the new Quench Protection System (n-QPS), the last months has been dedicated to n-QPS commissioning and to make it compatible with the high noise environment of the machine.

This success of 3.5 TeV, 3.5 times the previous more-than-25-years-old energy record of the Tevatron (Fermilab, USA) is the final milestone in the way to provide the HEP community with stable collisions at 7 TeV centre-of-mass, which should happen within days. Subsequently, a 2-year-long run is foreseen before the machine will be stopped for one year (in 2012) to carry out the definitive consolidation on the 13 kA splices. This massive consolidation campaign will allow LHC the go to the design energy of 14 TeV centre-of-mass (or 8.3 T in the main dipole with about 8 GJ of stored energy).

See also:http://press.web.cern.ch/press/PressReleases/Releases2010/PR05.10E.html  for more information and pictures.

Lucio Rossi