Large Hadron Collider

Valerio Mezzanotti for The New York Times

Updated: July 5, 2012
Call it the Hubble Telescope of Inner Space.
The Large Hadron Collider, located 300 feet underneath the French-Swiss border, is the world’s biggest and most expensive particle accelerator. It is designed to accelerate the subatomic particles known as protons to energies of 7 trillion electron volts apiece and then smash them together to create tiny fireballs, recreating conditions that last prevailed when the universe was less than a trillionth of a second old.
It is operated by CERN, the multinational research center headquartered in Geneva.
Whatever forms of matter and whatever laws and forces held sway Back Then — relics not seen in this part of space since the universe cooled 14 billion years ago — will spring fleetingly to life. If all goes well, they will leave their footprints in four mountains of hardware and computer memory that international armies of physicists have erected in the cavern.
After 16 years and $10 billion, on March 30, 2010, the collider finally began its work of smashing subatomic particles. The day was a milestone — delayed a year and a half by an assortment of technical problems — and brings closer a moment of truth for CERN and for the world’s physicists, who have staked their credibility and their careers, not to mention all those billions of dollars, on the conviction that they are within touching distance of fundamental discoveries about the universe.
In July 2012, physicists at CERN announced that they had discovered a new subatomic particle that looks for all the world like the Higgs boson, a key to understanding why there is diversity and life in the universe. The find, one of the biggest in the field in decades, was based on mountains of data produced by the Large Hadron Collider, making it an impressive opening act for a machine still operating at half power.
Looking Back in Time
Machines like CERN’s new collider get their magic from Einstein‘s equation of mass and energy. The more energy that these machines can pack into their little fireballs, in effect the farther back in time they can go, closer and closer to the Big Bang, the smaller and smaller things they can see.
The new hadron collider, scientists say, will take physics into a realm of energy and time where the current reigning theories simply do not apply, corresponding to an era when cosmologists think that the universe was still differentiating itself, evolving from a primordial blandness and endless potential into the forces and particles that constitute modern reality.

Cosmic Leapfrog
The advent of the CERN collider cements a shift in the balance of physics power away from American dominance that began in 1993, when Congress canceled the Superconducting Supercollider, a monster machine under construction in Waxahachie, Tex. The supercollider, the most powerful ever envisioned, would have sped protons around a 54-mile racetrack before slamming them together with 40 trillion electron volts.
For decades before that, physicists in the United States and Europe had leapfrogged one another with bigger, more expensive and, inevitably, fewer of these machines. The most powerful American accelerator now operating is the Tevatron, colliding protons and their antimatter opposites, antiprotons, with energies of a trillion electron volts apiece, at the Fermi National Accelerator Laboratory in Batavia, Ill. It is presently expected to run through 2010 or 2011.
Once upon a time, said Lyn Evans, who led the building of the CERN collider, “There was a nice equilibrium across the Atlantic. People used to come and go.”
Now, he said, “The center of gravity has moved to CERN.”
The Development of CERN
CERN was born amid vineyards and farmland in the countryside outside Geneva in 1954 out of the rubble of postwar Europe. It had a twofold mission of rebuilding European science and of having European countries work together.
Today, it has 20 countries as members. Yearly contributions are determined according to members’ domestic economies, and a result is a stable annual budget of about a billion Swiss francs. The vineyards and cows are still there, but so are strip malls and shopping centers.
It was here that the World Wide Web was born in the early 1990s, but the former director-general of CERN, Robert Aymar, joked recently that the lab’s greatest fame was as a locus of conspiracy in the novel “Angels and Demons,” by the author of “The DaVinci Code,” Dan Brown. The lab came into its own scientifically in the early ’80s, when Carlo Rubbia and Simon van der Meer won the Nobel Prize by colliding protons and antiprotons there to produce the particles known as the W and Z bosons, which are responsible for the so-called weak nuclear force that causes some radioactive decays.
Bosons are bits of energy, or quanta, that, according to the weird house rules of the subatomic world, transmit forces as they are tossed back and forth in a sort of game of catch between matter particles. The W’s and Z’s are closely related to photons, which transmit electromagnetic forces, or light.
The lab followed up that triumph by building a 17-mile-long ring, the Large Electron-Positron collider, or LEP, to manufacture W and Z particles for further study. The United States started and then abandoned its plans for an accelerator, which would have been named Isabelle, but in the meantime, CERN physicists had been mulling building their own giant proton collider in the LEP tunnel.
The Collider’s Cost Problems
In 1994 CERN’s governing council gave its approval. The United States eventually agreed to chip in $531 million for the project. CERN also arranged to borrow about $400 million from the European Investment Bank. Even so, there was a crisis in 2001 when the project was found to be 18 percent over budget, necessitating cutting other programs at the lab. The collider’s name comes from the word hadron, which denotes subatomic particles like protons and neutrons that feel the “strong” nuclear force that binds atomic nuclei.
Whether the Europeans would have gone ahead if the United States had still been in the game depends on whom you ask. Dr. Aymar, the former director, who was not there in the ’90s, said there was no guarantee then that the United States would have succeeded even if it had proceeded.
“Certainly in Europe the situation of CERN is such that we appreciate competition,” he said. “But we assume we are the leader and we have all intention to remain the leader. And we’ll do everything which is needed to remain the leader.”
Sunken Cathedrals
The guts of the collider are some 1,232 electromagnets, thick as tree trunks, long as boxcars, weighing in at 35 tons apiece, strung together like an endless train stretching around the gentle curve of the CERN tunnel.
In order to bend 7-trillion-electron-volt protons around in such a tight circle these magnets, known as dipoles, have to produce magnetic fields of 8.36 Tesla, more than 100,000 times the Earth’s field, requiring in turn a current of 13,000 amperes through the magnet’s coils. To make this possible the entire ring is bathed in 128 tons of liquid helium to keep it cooled to 1.9 degrees Kelvin, at which temperature the niobium-titanium cables are superconducting and pass the current without resistance.
Running through the core of this train, surrounded by magnets and cold, are two vacuum pipes, one for protons going clockwise, the other counterclockwise. Traveling in tight bunches along the twin beams, the protons will cross each other at four points around the ring, 30 million times a second. During each of these violent crossings, physicists expect that about 20 protons, or the parts thereof — quarks or gluons — will actually collide and spit fire. It is in vast caverns at those intersection points that the detectors, or “sunken cathedrals” in the words of a CERN theorist, Alvaro de Rujula, are placed to capture the holy fire.
Detectors And Their Quarry
Two of the detectors are specialized. One, called Alice, is designed to study a sort of primordial fluid, called a quark-gluon plasma, that is created when the collider smashes together lead nuclei.
The other, LHCb, will hunt for subtle differences in matter and antimatter that could help explain how the universe, which was presumably born with equal amounts of both, came to be dominated by matter.
The other two, known as Atlas and the Compact Muon Solenoid, or C.M.S. for short, are the designated rival workhorses of the collider, designed expressly to capture and measure every last spray of particle and spark of energy from the proton collisions.
Or as Katie McAlpine, who writes about science for the Atlas group, put it in “The L.H.C. Rap,”
“LHCb sees where the antimatter’s gone.
Alice looks at collisions of lead ions.
CMS and Atlas are two of a kind,
They’re looking for whatever new particles they can find.”
The last two, Atlas and C.M.S., represent complementary strategies for hunting one of the prime targets of the collider, a particle known as the Higgs boson, which is expected to disintegrate into a spray of lesser particles. Exactly which particles are produced depends on how massive the Higgs really is.
One telltale signature of the Higgs and other subatomic cataclysms is a negatively charged particle known as a muon, a sort of heavy electron that comes flying out at nearly the speed of light. Physicists measure muon momentum by seeing how much their paths bend in a magnetic field.
It is the need to have magnets strong enough and large enough to produce measurable bending, physicists say, that determines the gigantic size of the detectors.
The Compact Muon Solenoid weighs 12,000 tons, the heaviest scientific instrument ever made. It takes its name from a massive superconducting electromagnet that produces a powerful field running along the path of the protons.
Conversely, the magnetic field on Atlas wraps like tape around the proton beam. At 150 feet long and 80 feet high, Atlas is bigger than its rival, but it is much lighter, about 7,000 tons, about as much as the Eiffel Tower.
The two detectors have much in common, including “onion layers” of instruments to measure different particles and the ability to cope with harsh radiation and vast amounts of data. The central C.M.S. detector is made of strips of silicon that record the passage of charged particles. It is in effect a 60-megapixel digital camera taking 40 million pictures a second.
To manage this onslaught the teams’ computers have to perform triage, and winnow those events to a couple of hundred per second. Even so, the collider will produce the equivalent of 3 million DVDs worth of data every year, and a grid computing system of more than 100,000 processors from over 170 sites in 34 countries has been constructed to cope with it.
The competition between Atlas and the C.M.S. is in keeping with a long tradition of having rival teams and rival detectors at big experiments to keep each other honest and to cover all the bets.
At the Fermilab Tevatron, the teams, several hundred strong, are called CDF and D0. In the glory years 20 years ago at CERN, they were called UA1 and UA2. Over the years, as the machines have grown, so have the groups that built them, from teams to armies, 1,800 people from 34 countries for Atlas and 2,520 from 37 countries for the C.M.S. The other two experiments — Alice with 1,000 scientists, and LHCb with 663 — are only slightly smaller.
The Collider in Operation
The first experiments with the collider were delayed by over a year when an explosion vaporized an electrical connection and spewed tons of helium underneath the Swiss-French countryside in the fall of 2008. The explosion took place only nine days after the physicists celebrated threading the first protons around the 17-mile underground racetrack by drinking Champagne. The incident exposed a weakness in the connections between the collider’s thousands of magnets that will mean a longer wait until it is ready to operate at peak power.
On Nov. 23, 2009, the first collision was produced in a test of the collider systems’ ability to synchronize the beams, in which bunches of protons travel along at nearly the speed of light, and make them collide at the right points. The protons were at their so-called injection energies of 450 billion electron volts, a far cry from the energies the machine will eventually achieve.
Four months later, the collider went into full operation for the first time, whipping protons to 99 percent of the speed of light and to energy levels of 3.5 trillion electron volts apiece. That was cause for great celebration, but the machine is still operating at half of peak power.
Because of the defective joints and some mysteriously underperforming magnets, the collider will not run at or near full strength until at least late 2012.

 CERN is the world’s largest particle physics laboratory, located near Geneva at the border between Switzerland and France.
Its most ambitious project, the particle accelerator known as the Large Hadron Collider, above, began test operations in fall 2007. Technical problems postponed its true opening till 2010, when it began to work at half power.
Even at that limit, the data generated the collider led physicists in July 2012 to declare that they had discovered a new subatomic particle that looks for all the world like the Higgs boson, a key to understanding why there is diversity and life in the universe. The find, one of the biggest in the field in decades, was based on mountains of data produced by the Large Hadron Collider, making it an impressive opening act.
The name CERN derives from its original incarnation: the French Conseil Européen pour la Recherche Nucléaire, or European Council for Nuclear Research, which was formed in 1952 to help establish world-class fundamental physics research in Europe. Two years later, the council was dissolved and replaced by the European Organization for Nuclear Research. The name CERN was retained.