June 28, 2010

LHC Achieves New Milestone

Scientists working with the Large Hadron Collider (LHC) said they have moved a step closer to reaching their goal of unlocking the mysteries of the Universe.

The LHC has produced a record-breaking particle collision rate, which is about double the previous rate.

According to physicist Andrei Golutvin, the collider is now generating about 10,000 particle collisions per second.

The LHC is the world's highest-energy particle accelerator and is located in a 16 mile tunnel under the French-Swiss border.

The machine is operated by the European Organization for Nuclear Research (CERN), and is based near Geneva in Switzerland.

Scientists say this marks the start of turning the LHC into the world's most powerful particle collider.

"It's clear that the LHC is the new boy in town, but in two years running we're going to put Fermilab out of business," operation group leader Mike Lamont told BBC News.

The Tevatron particle accelerator at the Fermi National Accelerator Laboratory (Fermilab) in Illinois, USA, is the LHC's rival.  It has operated at higher intensities, but the current collision rate is a record for CERN.

The LHC is expected to eventually surpass the Fermilab eventually.

LHC engineers have slowly and carefully increased the energy and intensity of the proton beams.

This weekend, engineers smashed two beams together that consisted of three "bunches" of proton particles.

These bunches were at "nominal" intensity for the first time, which is the intensity the LHC was designed to work at.  This means each bunch consisted of as many as 100 billion protons.

The LHC smashed its first two particle beams together at the speed of light in November 2009.

It is currently running at half the energy it was designed for, but scientists hope to take the machine to the top energy of seven tera-electronvolts (TeV) per beam by 2013.

Stationed around the collider's ring are four large experiments designed to study new physics.  These are Compact Muon Solenoid (CMS), Atlas, Alice and LHCb, of which Golutvin is chief scientist.

The researchers hope to find an elusive sub-atomic particle known as Higgs boson, dubbed the "God particle," which explained why matter has mass.

Mike Lamont said that his team has recently achieved a record luminosity, which is a measure of the number of protons colliding per second.

Luminosity is key to a particle smasher's power, he said. More collisions means more chances of "really interesting physics, like [finding] the Higgs", Lamont explained told BBC.

Dr. John Ellis, one of CERN's top theoretical physicists, is among those on the hunt for the Higgs.  Ellis said he was very excited by the LHC's latest record.

"Protons are complicated particles, they've got quarks, [and other small particles], and colliding them is like colliding two garbage cans and watching carrots come out," he told BBC News.

"The more collisions we get, the closer we get to supersymmetry, dark matter, the Higgs boson and other types of new physics."

The theoretical physicist explained that collision rates depend on the bunch intensity, which is the number of protons in a bunch.

"Now we will be trying to increase the number of those bunches, and then probably in August we will spend quite a period of time just banging away and trying to get as many collisions as we can."

The ultimate goal is to reach 2,808 bunches in a beam.  The LHC team hopes that they achieve this by 2016.

Ellis said that as the luminosity increases, one of the things physicists at CERN will be on the look-out for is a mini black hole.

"It would be absolutely, fantastically exciting if we produced black holes at the LHC," he said.

"Then we would test our ideas about gravity, quantum physics, string theory. This would be much more exciting than finding a... Higgs boson or even dark matter."

Lamont said that before stepping up the intensity, scientists had to be certain the beam carrying bunches at nominal intensity was not going to become unstable.

"Up to now we've been working with very low intensities because we didn't want to risk any damage," he told BBC.

The two beams that produced the first high-energy collisions of seven tera-electronvolts (TeV) on March 30 contained four bunches each, but with relatively small number of protons in each bunch.

He said that as the number of protons increased, the team had to be really careful not to lose "a high-intensity beam in an uncontrolled way."

"The beam has got enough energy to melt a hole in the vacuum pipe, cause a vacuum leak into the magnet and helium leak into the vacuum pipe. It could be a real mess and would probably take us six months to repair," Lamont told BBC.

However, he said the consequences for the general public would be roughly nothing.

"Standard analogy is a British aircraft carrier going at 12 knots. Imagine it going into the Mont Blanc Bridge - it would be a real wreck, but it would not destroy half of Geneva."

"And given that this is all buried 100m under ground, the loss of energy would be very localized and safely contained in the tunnel."

The LHC is located in picturesque region of French-Swiss Alps, but Lamont said the team had few opportunities to get off the site and joy the area's natural beauty.

"The aim over this summer now is to get into a routine, where we're just turning the handle, delivering collisions on a regular basis to the experiments," he told BBC.

He added that this weekend's record is the first step towards that goal.

"Once we get into a routine, [scientists on individual experiments] can get on with their analysis, and we can gradually increase the intensity and at the same time catch our breath, go home see our families and maybe get into the mountains occasionally."


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