Today the Large Hadron Collider (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. With just one bunch of particles circulating in each direction, the beams can be made to cross in up to two places in the ring. From early in the afternoon, the beams were made to cross at points 1 and 5, home to the ATLAS and CMS detectors, both of which were on the lookout for collisions. Later, beams crossed at points 2 and 8, ALICE and LHCb.

“It’s a great achievement to have come this far in so short a time,” said CERN Director General Rolf Heuer. “But we need to keep a sense of perspective — there’s still much to do before we can start the LHC physics program.”

Beams were first tuned to produce collisions in the ATLAS detector, which recorded its first candidate for collisions at 14:22 this afternoon. Later, the beams were optimized for CMS. In the evening, ALICE had the first optimization, followed by LHCb.

“This is great news, the start of a fantastic era of physics and hopefully discoveries after 20 years’ work by the international community to build a machine and detectors of unprecedented complexity and performance,” said ATLAS spokesperson Fabiola Gianotti.

“The events so far mark the start of the second half of this incredible voyage of discovery of the secrets of nature,” said CMS spokesperson Tejinder Virdee from Imperial College London.

“It was standing room only in the ALICE control room and cheers erupted with the first collisions,” said ALICE spokesperson Jurgen Schukraft. “This is simply tremendous.”

“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.”

These developments come just three days after the LHC restart, demonstrating the excellent performance of the beam control system. 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 today beams have been circulating simultaneously in both directions, still at the injection energy.

Professor Norman McCubbin, Head of Particle Physics at the Science and Technology Facilities Council’s Rutherford Appleton Laboratory said, “Achieving low-energy collisions in the LHC so quickly after the re-start is a huge boost for the worldwide particle physics community. We look forward eagerly to the next stages in commissioning the LHC and to embarking on our quest to unlock new secrets of the Universe as the machine becomes fully operational.”

Prof. John Womersley, Director Science Programmes at STFC said, “The CERN accelerator team is doing a tremendous job and I congratulate them on achieving this vital step on the way to full operation of the LHC. As a scientist who has worked on this kind of machine myself, I understand the challenges involved – from here the CERN team will be working on increasing the number of particles in the beams and gradually ramping up the energy of these particles. The LHC will soon be the highest energy particle accelerator in the world, and in 2010 we can expect to see it start delivering new science.”

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.

Notes to Editors

Photos of the first collisions can be found here: http://press.web.cern.ch/press/PressReleases/Releases2009/PR17.09E.html

For photos inside the CERN Control Centre see: http://cdsweb.cern.ch/record/1223969?ln=fr

Follow LHC progress on twitter at www.twitter.com/cern

For photos, video and latest information see: http://press.web.cern.ch/press/lhc-first-physics/

See today’s press conference here: http://cdsweb.cern.ch/record/1223965

UK membership of CERN is funded by STFC. Background at http://www.stfc.ac.uk/PMC/PRel/STFC/lhcfullbeam.aspx

Contact:

Lucy Stone
STFC Press Officer
Rutherford Appleton Laboratory
+44 (0)1235 445627 / mobile +44 (0)7920 870125
lucy.stone@stfc.ac.uk