By: Science and Technology Facilities Council (STFC)
November 20, 2009 - Particle beams are once again circulating in the world's most powerful particle accelerator, CERN's Large Hadron Collider (LHC). A clockwise circulating beam was established at 9pm GMT this evening (20th Nov). This is an important milestone on the road towards first physics at the LHC, expected in 2010.
"It's great to see beam circulating in the LHC again," said CERN Director General Rolf Heuer. "We've still got some way to go before physics can begin, but with this milestone we're well on the way." The LHC circulated its first beams on 10 September 2008, but suffered a serious malfunction nine days later. A failure in an electrical connection led to serious damage, and CERN has spent over a year repairing and consolidating the machine to ensure that such an incident cannot happen again. "The LHC is a far better understood machine than it was a year ago," said CERN's Director for Accelerators, Steve Myers. "We've learned from our experience, and engineered the technology that allows us to move on. That's how progress is made."
The UK is one of the biggest contributors to the LHC project. Through the Science and Technology Facilities Council (STFC), which funds the UK particle physics programme, including the CERN subscription, the UK has contributed vital hardware, computing and scientific knowledge and has around 150 UK scientists currently involved in the experiment.
Professor Keith Mason, CEO of the STFC said "With this momentous experiment up and running again, our scientists will be able to further advance our understanding of the Universe. The LHC's particle collisions could help us find out if dark matter exists, whether there are extra dimensions of space-time and why some particles have mass. Whether the LHC confirms or denies leading theories, its results will start a new age in our understanding of physics and the entire Universe."
Professor Norman McCubbin from STFC's Rutherford Appleton Laboratory, added, "I'm sure every particle physicist has been feeling just a little bit impatient as the "re-start" of the LHC has drawn nearer. It's great to see beams circulating again, and the LHC back on course."
Recommissioning the LHC began in the summer, and successive milestones have regularly been passed since then. The LHC reached its operating temperature of 1.9 Kelvin, or about -271 Celsius, on 8 October. Particles were injected on 23 October, but not circulated. A beam was steered through three octants of the machine on 7 November, and circulating beams have now been re-established.
The next important milestone will be low-energy collisions, expected in about a week from now. These will give the experimental collaborations their first collision data, enabling important calibration work to be carried out. This is significant, since up to now, all the data they have recorded comes from cosmic rays. Ramping the beams to high energy will follow in preparation for collisions at 7 TeV (3.5 TeV per beam) next year.
Particle physics is a global endeavour, and CERN has received support from around the world in getting the LHC up and running again.
Professor Jon Butterworth, of University College London and one of the UK scientists involved in the LHC's ATLAS experiment, said, "It has been a tough year, but it will have been worth the wait. The LHC is going to open up a whole new landscape of physics for us. We've been stuck at the border for a year, but our visa has finally come through."
