large Hadron Collider Finally Smashing Properly

Large Hadron Collider Finally Smashing Properly

Physicists at the European Center for Nuclear Research celebrated 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 Tue sday: the world’s biggest physics machine, the Large Hadron Collider, finally began to collide subatomic particles.

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

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 gatherings of particle physicists all around the world, who have collectively staked the future of their profession on the idea that the new collider will eventually reveal new secrets of the

universe, like the identity of the dark matter that shapes the visible cosmos and the strang e particle known as the “Higgs,” 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 at the California Institute of Technology, where refreshments in a conference room overflowing with Los Angeles-area physicists attending a midnight remote viewing included matzos, chips and pizza.

Rolf 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 added: “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,” F abiola Gianotti, a spokeswoman for CERN, said of one of the giant particle detectors at the collider, known as Atlas. Guido Tonelli, leader of a rival detector called C.M.S. said, “We are really starting physics.”

The success in colliding protons marks 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 is riddled with thousands of such joints, the result of what Lucio Rossi, head of magnets at CERN, sai d stemmed from 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 7 trillion electron volts and 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-volt Tevatron at the Fermi National Accelerator Laboratory in Illinois, which is smaller but has been running for years and thus has a head start in data. After that, the CERN machine will 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 further back in time they can go, closer and closer to the Big Bang, and the smaller and smaller things they can see.

The first modern accelerator was the cyclotron, built by Ernest Lawrence at the University of California, Berkeley, in 1932. It was a foot in diameter and boosted protons to energies of 1.25 million electron volts, the unit of choice for mass and energy in physics. By comparison, an electron, the lightest well-known particle, is about half a million electron volts, and a proton about a billion.

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 end was decreed in 1993, the U.S. Congress canceled the Superconducting Supercollider, a 54-mile 20-trillion-electron-volt machine being built underneath Waxahachie, Texas, after its projected cost ballooned to $11 billion.

The following year, CERN, a 20-nation consortium that grew from the ashes of World War II and has provided a template for other pan-European organizations like the European Space Agency and the European Southern Observatory, approved its own big collider. With a budget and dues established by treaty, CERN 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 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 st rength. According to theoretical models, that would stretch out the time it should take to achieve the collider’s main goals, including producing a particle known as the Higgs boson, which is thought to be responsible for imbuing other elementary particles with mass.

Engineers also want to identify the dark matter that astronomers say makes up 25 percent of the cosmos, and test more exotic ideas like extra dimensions. Until then, the American accelerator Tevatron will chase CERN for big goals like the Higgs boson, physicists say. The CERN experimenters will spend the next 4 to 6 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 Dr. Newm an of Caltech, 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 U.S. 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 email message. “The dreams of a lifetime are waiting, and hopefully not much longer.”