LHC back online

Light the fuse and stand back. Are they CERNtain it will work this time.

"Cern Large Hadron Collider restarts after 14 months"

by

Paul Rincon

BBC News

The Large Hadron Collider experiment has re-started after a 14-month hiatus while the machine was being repaired.

Engineers have made two stable proton beams circulate in opposite directions around the machine, which is in a tunnel beneath the French-Swiss border.

The team may try to increase the £6bn ($10bn) collider's energy to record-breaking levels this weekend.

The LHC is being used to smash together beams of protons in a bid to shed light on the nature of the Universe.

It is the world's largest machine and is housed in a 27km-long circular tunnel.

During the experiment, scientists will search for signs of the Higgs boson, a sub-atomic particle that is crucial to our current understanding of physics. Although it is predicted to exist, scientists have never found it.

Dozens of giant superconducting magnets that accelerate the particles at the speed of light have had to be replaced after faults developed just days after the collider was inaugurated last year.

Operated by the European Organization for Nuclear Research (Cern), the LHC will create similar conditions to those which were present moments after the Big Bang.

The BBC's Pallab Ghosh in Geneva says the restart of the collider was the moment the scientists had been waiting for.

It means they can once again go in search of the new discoveries they believe will roll back the frontiers of understanding our universe, says our correspondent.

"It's great to see beams circulating in the LHC again," said Cern's director-general Rolf Heuer.

"We've still got some way to go before physics can begin, but with this milestone we're well on the way."

Engineers sent their first beam all the way round the LHC's circumference 100m underground after 1930 GMT on Friday.

Record attempt

The beams themselves are made up of "packets" - each about a metre long - containing billions of protons. But they would disperse if left to their own devices.

Electrical forces had to be used to "capture" the protons. This keeps them tightly huddled in packets, for a stable, circulating beam.

Engineers had not been expected to try for a circulating beam before 0600 GMT on Saturday.

James Gillies, Cern's director of communications, told BBC News: "It happened faster than anyone could have dreamed of."

"Everything went very smoothly."

Dr Gillies said that if everything continued to go well, Cern might try to reach a record-breaking beam energy of 1.2 trillion electron volts this weekend.

Only the Tevatron particle accelerator in Chicago, US, has approached this energy, operating at just under one trillion electron volts.

But other team members want to keep the beam circulating at low energy and try for the machine's first proton beam collisions.

"The LHC is a far better understood machine than it was a year ago," said Steve Myers, Cern's director for accelerators.

"We've learned from our experience, and engineered the technology that allows us to move on. That's how progress is made."

There are some 1,200 superconducting magnets which form the LHC's main "ring".

These magnets bend proton beams in opposite directions around the tunnel at close to the speed of light.

At allotted points around the tunnel, the proton beams cross paths, smashing into one another with enormous energy. Large "detector" machines located at the crossing points will scour the wreckage of these collisions for discoveries that should extend our knowledge of physics.

Engineers first circulated a beam all the way around the LHC on 10 September 2008.

But just nine days later, an electrical fault in one of the connections between superconducting magnets caused a tonne of liquid helium to leak into the tunnel.

Liquid helium is used to cool the LHC to its operating temperature of 1.9 kelvin (-271C; -456F).

The machine has been shut down ever since the accident, to allow repairs to take place.

Professor Norman McCubbin, from the UK's Rutherford Appleton Laboratory in Didcot, added: "I'm sure every particle physicist has been feeling just a little bit impatient as the 're-start' of the LHC has drawn nearer. It's great to see beams circulating again."

The damage caused to the collider meant 53 superconducting magnets had to be replaced and about 200 electrical connections repaired.

Engineers have also been installing a new early warning system which could prevent incidents of the kind which shut down the experiment.

Cern has spent some 40m Swiss Francs (£24m) on repairs to the collider.

""Big Bang" experiment advancing fast"

by

Jonathan Lynn

November 21st, 2009

Reuters

After a year's delay, scientists at the world's biggest accelerator have restarted an experiment to recreate "Big Bang" conditions that had sparked suggestions the earth would be sucked in by millions of black holes.

Scientists at the European Organization for Nuclear Research (CERN) have established circulating particle beams in both directions in the underground Large Hadron Collider, a step that is already beyond where the experiment stalled during a first attempt in September 2008, CERN spokesman James Gillies said.

The high-profile experiment, through which tiny particles are smashed in a bid to learn more about the birth of the universe, failed just nine days after it was launched due to a technical problem that took longer than expected to fix.

"We are further advanced now than where we were after five days of experiment last year," said CERN's Director for Accelerators Steve Myers, saying the extra year had allowed researchers to upgrade instrumentations and computer software.

Myers added that researchers had increased the sensitivity of the protections at the 10 billion Swiss franc ($9.82 billion) collider under the French-Swiss border.

"If anything happens, we would not have the same amount of damage we had last year," he said.

CERN, a 55-year-old organization that counts 10,000 scientists and technicians worldwide working on its research projects, has vigorously rebuffed any suggestion the ground-breaking experiment would cause the world to end.

CERN's Director General Rolf Heuer said getting the experiment re-started had been an "herculean effort."

"We've still got some way to go before physics can begin, but with this milestone we're well on the way," he said.

If things continue to progress at this speed, scientists may be able to accelerate particles at the highest energy level ever tested before Christmas, although high-energy collisions that may shed light on the secrets of the universe would only happen in the new year, Myers said.

The experiment will be fully under way when the particle beams will be smashed at high energy levels. This will most likely happen in January.

The next important step in the experiment will be low-energy collisions, expected in about a week from now, CERN said.

"Quick restart of Big Bang machine stuns scientists"

November 21st, 2009

USA Today

Scientists moved Saturday to prepare the world's largest atom smasher for exploring the depths of matter after successfully restarting the $10 billion machine following more than a year of repairs.

The nuclear physicists working on the Large Hadron Collider were surprised that they could so quickly get beams of protons whizzing near the speed of light during the restart late Friday, said James Gillies, spokesman for the European Organization for Nuclear Research.

The machine was heavily damaged by a simple electrical fault in September last year.

Some scientists had gone home early Friday and had to be called back as the project jumped ahead, Gillies said.

At a meeting early Saturday "they basically had to tear up the first few pages of their PowerPoint presentation which had outlined the procedures that they were planning to follow," he said. "That was all wrapped up by midnight. They are going through the paces really very fast."

The European Organization for Nuclear Research has taken the restart of the collider step by step to avoid further setbacks as it moves toward new scientific experiments — probably starting in January — regarding the makeup of matter and the universe.

CERN, as it is known, had hoped by 7 a.m. (0600 GMT) Saturday to get the beams to travel the 27-kilometer (17-mile) circular tunnel under the Swiss-French border, but things went so well Friday evening that they had achieved the operation seven hours earlier.

Praise from scientists around the world was quick. "First beam through the Atlas!" whooped an Internet message from Adam Yurkewicz, an American scientist working on the massive Atlas detector on the machine.

"I congratulate the scientists and engineers that have worked to get the LHC back up and running," said Dennis Kovar of the U.S. Department of Energy, which participates in the project.

"The LHC is a machine unprecedented in size, in complexity, and in the scope of the international collaboration that has built it over the last 15 years," said Kovar.

The next step, possibly later Saturday, was to decide whether to collide beams in the detectors to get necessary measuring data or to try using the machine to accelerate the protons to higher energy than any machine has ever reached, said Gillies.

In the meantime CERN is using about 2,000 superconducting magnets — some of them 15 meters (50 feet) long — to improve control of the beams of billions of protons so they will remain tightly bunched and stay clear of sensitive equipment.

Gillies said the scientists are being very conservative.

"They're leaving a lot of time so that the guys who are operating the machine are under no pressure whatsoever to tick off the boxes and move forward," he said.

Officials said Friday evening's progress was an important step on the road toward scientific discoveries at the LHC, which are expected in 2010.

"We've still got some way to go before physics can begin, but with this milestone we're well on the way," CERN Director General Rolf Heuer said.

With great fanfare, CERN circulated its first beams Sept. 10, 2008. But the machine was sidetracked nine days later when a badly soldered electrical splice overheated and set off a chain of damage to the magnets and other parts of the collider.

Steve Myers, CERN's director for accelerators, said the improvements since then have made the LHC a far better understood machine than it was a year ago.

The LHC is expected soon to be running with more energy the world's current most powerful accelerator, the Tevatron at Fermilab near Chicago. It is supposed to keep ramping up to seven times the energy of Fermilab in coming years.

This will allow the collisions between protons to give insights into dark matter and what gives mass to other particles, and to show what matter was in the microseconds of rapid cooling after the Big Bang that many scientists theorize marked the creation of the universe billions of years ago.

When the machine is fully operational, the magnets will control the beams of protons and send them in opposite directions through two parallel tubes the size of fire hoses. In rooms as large as cathedrals 300 feet (100 meters) below the ground the magnets will force them into huge detectors to record what happens.

The LHC operates at nearly absolute zero temperature, colder than outer space, which allows the superconducting magnets to guide the protons most efficiently.

Physicists have used smaller, room-temperature colliders for decades to study the atom. They once thought protons and neutrons were the smallest components of the atom's nucleus, but the colliders showed that they are made of quarks and gluons and that there are other forces and particles. And scientists still have other questions about antimatter, dark matter and supersymmetry they want to answer with CERN's new collider.

The Superconducting Super Collider being built in Texas would have been bigger than the LHC, but in 1993 the U.S. Congress canceled it after costs soared and questions were raised about its scientific value

Gillies said the LHC should be ramped up to 3.5 trillion electron volts some time next year, which will be 3 1/2 times as powerful as Fermilab. The two laboratories are friendly rivals, working on equipment and sharing scientists.

But each would be delighted to make the discovery of the elusive Higgs boson, the particle or field that theoretically gives mass to other particles. That is widely expected to deserve the Nobel Prize for physics.

More than 8,000 physicists from other labs around the world also have work planned for the LHC. The organization is run by its 20 European member nations, with support from other countries, including observers Japan, India, Russia and the U.S. that have made big contributions.