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*Beams collided at 7 Tev *

Geneva 30 March 2010. Beams collided at 7 TeV in the LHC at 13:06 CEST today, marking the start of the LHC research programme. Particle physicists around the world are looking forward to a potentially rich harvest of new physics as the LHC begins its first long run at an energy three and a half times higher than previously achieved at a particle accelerator.

*"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."*

* *

*"This is the moment we have been waiting and preparing for",* said ALICE spokesperson J?rgen Schukraft. *"We're very much looking forward to the results from proton collisions, and later this year from lead-ion collisions, to give us new insights into the nature of the strong interaction and the evolution of matter in the early Universe."***

*"LHCb is ready for physics,"* said the experiment's spokesperson Andrei Golutvin, *"we have a great research programme ahead of us exploring the nature of matter-antimatter asymmetry more profoundly than has ever been done before."*

CERN will run the LHC for 18-24 months with the objective of delivering enough data to the experiments to make significant advances across a wide range of physics channels. As soon as they have "re-discovered" 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. With the amount of data expected, called one inverse femtobarn by physicists, the combined analysis of ATLAS and CMS will be able to explore a wide mass range, and there's even a chance of discovery if the Higgs has a mass near 160 GeV. If it's much lighter or very heavy, it will be harder to find in this first LHC run.

For supersymmetry, ATLAS and CMS will each have enough data to double today's sensitivity to certain new discoveries. Experiments today are sensitive to some supersymmetric particles with masses up to 400 GeV. An inverse femtobarn at the LHC pushes the discovery range up to 800 GeV.

*"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."*

Even at the more exotic end of the LHC's potential discovery spectrum, this LHC run will extend the current reach by a factor of two. LHC experiments will be sensitive to new massive particles indicating the presence of extra dimensions up to masses of 2 TeV, where today's reach is around 1 TeV.

*"Over 2000 graduate students are eagerly awaiting data from the LHC experiments,*" said Heuer. *"They're a privileged bunch, set to produce the first theses at the new high-energy frontier."*

Following this run, the LHC will shutdown for routine maintenance, and to complete the repairs and consolidation work needed to reach the LHC's design energy of 14 TeV following the incident of 19 September 2008. 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."*

CERN sets date for first attempt at 7 TeV collisions in the LHC

Geneva, 23 March 2010. With beams routinely circulating in the Large Hadron Collider at 3.5 TeV, the highest energy yet achieved in a particle accelerator, CERN has set the date for the start of the LHC research programme. The first attempt for collisions at 7 TeV (3.5 TeV per beam) is scheduled for 30 March.

*"With two beams at 3.5 TeV, we're on the verge of launching the LHC physics programme,"* explained CERN's Director for Accelerators and Technology, Steve Myers. *"But we've still got a lot of work to do before collisions*. *Just lining the beams up is a challenge in itself: it's a bit like firing needles across the Atlantic and getting them to collide half way*.*"*

* *

Between now and 30 March, the LHC team will be working with 3.5 TeV beams to commission the beam control systems and the systems that protect the particle detectors from stray particles. All these systems must be fully commissioned before collisions can begin.

*"The LHC is not a turnkey machine," *said CERN Director General Rolf Heuer. * "The machine is working well, but we're still very much in a commissioning phase and we have to recognize that the first attempt to collide is precisely that. It may take hours or even days to get collisions."*

The last time CERN switched on a major new research machine, the Large Electron Positron collider, LEP, in 1989 it took three days from the first attempt to collide beams to the first recorded collisions.

The current LHC run began on 20 November 2009, with the first circulating beam at 0.45 TeV. Milestones were quick to follow, with twin circulating beams established by 23 November and a world record beam energy of 1.18 TeV being set on 30 November. By the time the LHC switched off for 2009 on 16 December, another record had been set with collisions recorded at 2.36 TeV and significant quantities of data recorded. Over the 2009 part of the run, each of the LHC's four major experiments, ALICE, ATLAS, CMS and LHCb recorded over a million particle collisions, which were distributed smoothly for analysis around the world on the LHC computing grid. The first physics papers were soon to follow. After a short technical stop, beams were again circulating on 28 February 2010, and the first acceleration to 3.5 TeV was on 19 March.

Once 7 TeV collisions have been established, the plan is to run continuously for a period of 18-24 months, with a short technical stop at the end of 2010. This will bring enough data across all the potential discovery areas to firmly establish the LHC as the world's foremost facility for high-energy particle physics.

Geneva, 30 November 2009. CERN's Large Hadron Collider has today become the world's highest energy particle accelerator, having accelerated its twin beams of protons to an energy of 1.18 TeV in the early hours of the morning. This exceeds the previous world record of 0.98 TeV, which had been held by the US Fermi National Accelerator Laboratory's Tevatron collider since 2001. It marks another important milestone on the road to first physics at the LHC in 2010.

"We are still coming to terms with just how smoothly the LHC commissioning is going," said CERN Director General Rolf Heuer. "It is fantastic. However, we are continuing to take it step by step, and there is still a lot to do before we start physics in 2010. I'm keeping my champagne on ice until then." Last nights achievement brings further confirmation that the LHC is progressing smoothly towards the objective of first physics early in 2010.The world record energy was first broken yesterday evening, when beam 1 was accelerated from 450 GeV, reaching 1050 GeV (1.05 TeV) at 21:28, Sunday 29 November. Three hours later both LHC beams were successfully accelerated to 1.18 TeV, at 00:44, 30 November.

"I was here 20 years ago when we switched on CERNs last major particle accelerator, LEP," said Research and Technology Director Steve Myers. "I thought that was a great machine to operate, but this is something else. What took us days or weeks with LEP, were doing in hours with the LHC. So far, it all augurs well for a great research programme."

Next on the schedule is a concentrated commissioning phase aimed at increasing the beam intensity before delivering good quantities of collision data to the experiments before Christmas. So far, all the LHC commissioning work has been carried out with a low intensity pilot beam. Higher intensity is needed to provide meaningful proton-proton collision rates. The current commissioning phase aims to make sure that these higher intensities can be safely handled and that stable conditions can be guaranteed for the experiments during collisions. This phase is estimated to take around a week, after which the LHC will be colliding beams for calibration purposes until the end of the year.

First physics at the LHC is scheduled for the first quarter of 2010, at a collision energy of 7 TeV (3.5 TeV per beam).

Geneva, 23 November 2009. CERN Director General Rolf Heuer:

Today 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. 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 programme."

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 optimised for CMS. In the evening, ALICE had the first optimisation, 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.

"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.

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.

Geneva, 20 November 2009. CERN Director General Rolf Heuer Rolf Heuer:

"Earlier this week, the LHC was handed over for operation, and I rediscovered the long lost reflex of glancing at the status screens of CERN's flagship accelerator at every opportunity. All being well, we'll start injecting particles into the LHC tonight.

We've been here before, in September 2008. This time, however, it's different. The LHC is a much better understood machine than it was a year ago, and we can look forward with confidence to a smooth transition into physics. There will undoubtedly be hitches along the way, there always are. Magnets will trip, and there'll be power outages, but this is all normal in the operation of a major particle accelerator.

By the time you come into work next week, I hope we'll have beams circulating in the LHC. Whatever happens over the weekend, you will be able to follow progress on the CERN website, or at www.twitter.com/cern.

Circulating beam is an important milestone on the way to physics, but there is still much to do. In 2008, we showed that the LHC works beautifully as a particle storage ring, but we've yet to operate it as an accelerator and a collider. With luck, we should accomplish those objectives before the end of 2009, setting us up nicely for physics early in the New Year."

 


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