First Physics a smashing success at the LHC

By Tushna Commissariat

The Large Hadron Collider (LHC) at CERN reached another significant milestone yesterday at 12.06BST, achieving proton collisions at 7 trillion electron volts (TeV).

This is the highest amount of energy ever expelled in a particle accelerator under laboratory conditions (3.5 TeV per proton beam). The LHC is poised for its first long run at an energy level three and a half times higher than previously achieved with a particle accelerator.

An event as recorded by the LHC CMS experiment. Photo credit: CERN

This historic moment is the start of a two-year campaign that will hopefully help scientists make new discoveries about our Universe and better understand its very fabric.

“It’s a great day to be a particle physicist” said CERN Director General Rolf Heuer. “A lot of people have waited a long time for this moment, but their patience and dedication is starting to pay dividends.”

“With these record-shattering collision energies, the LHC experiments are propelled into a vast region to explore, and the hunt begins for dark matter, new forces, new dimensions and the Higgs boson” said ATLAS collaboration spokesperson Fabiola Gianotti. “The fact that the experiments have published papers already on the basis of last year’s data bodes very well for this first physics run.”

“We’ve all been impressed with the way the LHC has performed so far,” said Guido Tonelli, spokesperson of the CMS experiment, “and it’s particularly gratifying to see how well our particle detectors are working while our physics teams worldwide are already analysing data. We’ll address soon some of the major puzzles of modern physics like the origin of mass, the grand unification of forces and the presence of abundant dark matter in the universe. I expect very exciting times in front of us.”

There were a few minor complications earlier on in the day and it took three attempts before the machine was safely accelerating beams at 3.5 TeV. An electric perturbation, which has been seen in other accelerators, made the protection system stop the magnets as the system was set at a very high sensitivity. A repeat of September 2008 was to be avoided at all costs, and scientists preferred having the system so sensitive that it would even trigger at very small or ‘fake’ alarms.

The machine was restarted soon after and reached a rate where collisions were seen at 7 TeV. Latest reports from CERN said that the various experiments have recorded thousands of events within an hour of stable and colliding beams.

CERN will run the LHC for 18-24 months with the objective of delivering enough data from the experiments to make significant advances across a wide range of physics channels. As soon as they have “rediscovered” the known Standard Model particles, a necessary precursor to looking for new physics, the LHC experiments will start the systematic search for the Higgs boson.

“The LHC has a real chance over the next two years of discovering supersymmetric particles,” explained Heuer, “and possibly giving insights into the composition of about a quarter of the Universe.”

Following this run, the LHC will shut down for routine maintenance, and to complete the repairs and consolidation work needed to reach the LHC’s design energy of 14 TeV . Traditionally, CERN has operated its accelerators on an annual cycle, running for seven to eight months with a four to five month shutdown each year. Being a cryogenic machine operating at very low temperature, the LHC takes about a month to bring up to room temperature and another month to cool down. A four-month shutdown as part of an annual cycle no longer makes sense for such a machine, so CERN has decided to move to a longer cycle with longer periods of operation accompanied by longer shutdown periods when needed.

“Two years of continuous running is a tall order both for the LHC operators and the experiments, but it will be well worth the effort,” said Heuer. “By starting with a long run and concentrating preparations for 14 TeV collisions into a single shutdown, we’re increasing the overall running time over the next three years, making up for lost time and giving the experiments the chance to make their mark.”

This entry was posted on 31 March, 2010 at 09:27 and is filed under News & discovery. You can follow any responses to this entry through the RSS 2.0 feed.