The Large Hadron Collider has launched a new era for particle physics. Today at 1:06 p.m. Central European Summer Time (CEST) at CERN in Geneva, Switzerland, the first particles collided at the record energy of seven trillion electron volts (TeV). These collisions mark the start of a decades-long LHC research program, and the beginning of the search for discoveries by thousands of scientists around the world.
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“Today’s first 7 TeV collisions are a great start for LHC science,” said Dr. Dennis Kovar, Associate Director of Science for High Energy Physics at the U.S. Department of Energy. “We eagerly anticipate the work of the world’s physicists as they begin their search for dark matter, extra dimensions, and the ever-elusive Higgs boson.”
Today’s proton collisions were recorded by the LHC experiments’ particle detectors, known by their acronyms: ATLAS, CMS, ALICE and LHCb. While the LHC accelerator brings the protons up to their maximum energy and steers them around the 16-mile ring into collision, the experiments use massive particle detectors to record and analyze the collision debris.
“The LHC experiments are the world’s largest and most complex scientific instruments, and scientists from American universities and laboratories have made vital contributions to each of them,” said Dr. Edward Seidel, Acting Assistant Director of the National Science Foundation’s Directorate For Mathematical and Physical Sciences. “We wish all the LHC scientists success in their quest to solve some of the most profound mysteries of our universe.”
More than 1,700 scientists, engineers, students and technicians from 89 American universities, seven U.S. Department of Energy (DOE) national laboratories, and one supercomputing center helped design, build and operate the LHC accelerator and its four massive particle detectors. American participation is supported by the DOE’s Office of Science and the National Science Foundation (NSF).
Now, the real work begins for the LHC teams. Over the next 18 to 24 months, the LHC accelerator will deliver enough collisions at 7 TeV to enable significant advances in a number of research areas. As data begins to pour from their detectors, more than 8,000 LHC scientists around the world will sift through the flood in search of the tiny signals that could indicate discovery.
“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.”
The DOE’s Brookhaven National Laboratory and Fermi National Accelerator Laboratory are the host laboratories for the U.S. groups participating in the ATLAS and CMS experiments, respectively. Scientists from American universities and laboratories, who comprise more than 20% of the ATLAS collaboration and 35% of CMS, have played major roles in the construction of both detectors, and join thousands of international colleagues as they operate the detector and analyze the collision data that will be collected in the coming years. In addition, Lawrence Berkeley National Laboratory is the host laboratory for U.S. groups participating in ALICE, with American scientists contributing 10% of the ALICE collaboration.
The United States is also home to major national and regional computing centers that, as part of the Worldwide LHC Computing Grid, enable scientists in the United States and around the world to access the enormous amount of data generated by the LHC experiments. Brookhaven National Laboratory and Fermi National Accelerator Laboratory, host to major “Tier-1” computing centers, are the first stop in the U.S. for data from the ATLAS and CMS experiments, respectively. The data are further distributed to smaller NSF and DOE-funded “Tier-2” and “Tier-3” computing centers across the country, where physicists will conduct the analyses that may lead to LHC discoveries.
LHC research programme gets underway
Text of the CERN Press Release:
Geneva 30 March 2010. Beams collided at 7 TeV in the LHC at 13:06 CEST, 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 Jürgen 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.”
