European Collider Begins Its Subatomic Exploration

In a control room, a scientist toasted the start of the Large Hadron Collider outside Geneva on Tuesday.
By DENNIS OVERBYE
Published: March 30, 2010

PASADENA, Calif. — After 16 years and $10 billion — and a long morning of electrical groaning and sweating — there was joy in the meadows and tunnels of the Swiss-French countryside Tuesday: the world’s biggest physics machine, the Large Hadron Collider, finally began to make subatomic particles collide.

After two false starts due to electrical failures, protons that were whipped to more than 99 percent of the speed of light and to record-high energy levels of 3.5 trillion electron volts apiece raced around a 17-mile underground magnetic track outside Geneva a little after 1 p.m. local time. They crashed together inside apartment-building-size detectors designed to capture every evanescent flash and fragment from microscopic fireballs thought to hold insights into the beginning of the universe.

The soundless blooming of proton explosions was accompanied by the hoots and applause of scientists crowded into control rooms at CERN, the European Organization for Nuclear Research, which built the collider. The relief spread to bleary-eyed gatherings of particle physicists around the world, who have collectively staked the future of their profession on the idea that the collider will eventually reveal new secrets of the universe.

Among their top goals are finding the identity of the dark matter that shapes the visible cosmos and the strange particle known as the Higgs boson, which is thought to imbue other particles with mass. Until now, these have been tantalizingly out of reach.

“We’re expecting some answers,” said David Politzer, a Nobel laureate and professor at the California Institute of Technology, where a conference room overflowed with Los Angeles-area physicists attending a midnight remote viewing, with refreshments including matzos, chips and pizza.

Rolf-Dieter Heuer, director general of CERN, speaking from Japan, said the new collider “opens a new window of discovery and it brings, with patience, new knowledge of the universe and the microcosm.”

“It shows what one can do in bringing forward knowledge,” he said, adding, “It will also bring out an army of children and young people who will get into the private sector and academia.”

“We are all proud and so happy,” Fabiola Gianotti, a spokeswoman for CERN, said of one of the giant particle detectors at the collider, known as Atlas.

Guido Tonelli, spokesman for a rival detector called C.M.S., said, “We are really starting physics.”

The success in producing proton collisions represents a remarkable comeback for CERN, but the lab is still only halfway back to where it wanted to be. Only a year and a half ago, the first attempt to start the collider ended with an explosion that left part of its tunnel enveloped in frigid helium gas and soot when an electrical connection between two of the powerful magnets that steer the protons vaporized.

A subsequent investigation revealed that the collider was riddled with thousands of such joints, a result of what Lucio Rossi, head of magnets at CERN, said was a “lack of adequate risk analysis,” in a recent report in the online journal Superconductor Science and Technology. As a result, the collider, which was designed to accelerate protons to seven trillion electron volts, then smash them together to reveal particles and forces that reigned during the first trillionth of a second of time as we know it, can only be safely run for now at half power.

CERN physicists say that operating the collider for a year and a half at this energy level should allow them to gather enough data to start catching up with its American rival, the trillion-electron-volt Tevatron at the Fermi National Accelerator Laboratory in Illinois. The Tevatron is smaller but has been running for years and thus has a head start in data. After that, the CERN machine will be shut down for a year so that the connections can be rebuilt.

Particle colliders get their oomph from Einstein’s equation of mass and energy. The more energy — denoted in the physicists’ currency of choice, electron volts — that these machines can pack into their little fireballs, the farther back in time they can go, closer and closer to the Big Bang, and the smaller and smaller are the things they can see.

The first modern accelerator was the cyclotron, built by Ernest Lawrence at the University of California, Berkeley, in the 1930s. An early version was a foot in diameter and accelerated protons to energies of 1.25 million electron volts.

Over the last century, universities and then nations leapfrogged each other, building bigger machines to peer deeper into the origins of the universe. But the race ended in 1993, when Congress canceled the Superconducting Supercollider, a 54-mile, 20 trillion-electron-volt machine being built underneath Waxahachie, Tex., after its projected cost ballooned to $11 billion.

The following year, CERN approved its own big collider. CERN, a 20-nation consortium that grew from the ashes of World War II, has provided a template for other pan-European organizations like the European Space Agency and the European Southern Observatory. With a budget and dues established by treaty, the organization enjoys a long-term stability that is the envy of American labs. Last winter, Europe took the lead for good when test collisions at the Hadron collider achieved energies of 1.18 trillion electron volts.

The collider first ramped up its beams to 3.5 trillion electron volts two weeks ago, but the engineers took pains to prevent them from colliding so as not to steal the thunder from what was billed as First Physics Day on Tuesday.

Because of the defective joints and some mysteriously underperforming magnets, it will still be three years at least before CERN’s collider runs at or near full strength. According to theoretical models, that would stretch out the time it should take to achieve the collider’s main goals, like producing the Higgs boson and testing more exotic ideas like extra dimensions.

Until then, the Tevatron will chase CERN for big goals like the Higgs boson, physicists say. The CERN experimenters will spend the next four to six months learning how their detectors work and rediscovering known physics. Then, anything is possible.

“It’s very exciting because we are entering a new energy range,” said Harvey Newman, a Caltech professor who works on the C.M.S. experiment. “We’re looking at all kinds of exotic things,” he said, including signs of extra dimensions. The possibilities begin between the middle and end of this year.”

Michael Barnett, a physicist from the Lawrence Berkeley National Laboratory, said that he had worked on an experiment for the Superconducting Supercollider for 10 years until the project was canceled by Congress, and later spent 16 years on the Atlas experiment at the CERN collider.

“We are on this planet and in this universe a short time,” he wrote in an e-mail message. “The dreams of a lifetime are waiting, and hopefully not much longer.”

Correction: An earlier version of this article incorrectly identified Fabiola Gianotti as a spokesman for CERN. She is a spokeswoman.