Physicists look at initial data from Large Hadron Collider

Three physicists who took winter trips to the Large Hadron Collider are beginning to see some real data from the planet`s biggest experiment.

Last Updated: Jan 07, 2010, 18:37 PM IST

Washington: Three physicists who took winter trips to the Large Hadron Collider are beginning to see some real data from the planet`s biggest experiment.
Last month the ATLAS experiment at the Large Hadron Collider (LHC) began recording proton-proton collisions at a record energy of 2.36 trillion electron volts.

That could include the Higgs boson, a particle predicted by the Standard Model of particle physics. The model theorises that space is filled with a Higgs field and particles acquire their masses by interacting with the field.

The multibillion-dollar collider made news on September 2008, when it sent its first beam of protons around 17 miles of underground tunnel near Geneva, Switzerland.

But breakdowns in the machine`s high-current electrical connections forced a complete shutdown for more than a year of repairs and tests.

"The data look just beautiful," said Soeren Prell, an Iowa State University (ISU) associate professor of physics and astronomy.

Prell has been looking at the first data recorded with the ATLAS experiment`s silicon pixel detector. The pixel detector is the innermost part of ATLAS, one of two giant, general purpose detectors at the collider.

ATLAS will measure the paths, energies and identities of the particles created when protons or lead ions collide at unprecedented energies. The pixel detector uses 80 million pixels to make precise measurements as close to the particle collisions as possible.

Prell said the pixel detector is already sending physicists fairly clean data with very little background noise. It has a resolution down to 10 millionths of a metre, which has to be just as precisely aligned.

The detector`s data also has to be distributed to physicists worldwide for study and analysis. Jim Cochran, Prell`s ISU colleague, is the ATLAS experiment analysis support manager for the US. He has to ensure researchers have the data they need for their analyses.

And, so far, the experiment`s analysis system has been able to keep up with the data. But that`s going to be a bigger challenge when the collider is turned back on in February and begins running at higher energies and much higher collision rates.

"One of the concerns I`ve had is whether we`ll be able to handle the data loads we`re expecting," Cochran said. "We have to have our computing systems optimised so we can do it. We`ve already had 700,000 collision events and that`s nothing compared to what`s coming."

Physicists from around the world cheered on Nov 20 last year, when the collider once again sent protons racing through its tunnel. Three days later the machine recorded its first proton-proton collisions.

And on Nov 30 it set a new world record when it accelerated two beams of protons to a total energy of 2.36 trillion electron volts, said an ISU release.

Physicists at CERN, the European Organisation for Nuclear Research, shut down the collider on Dec 16 to prepare for even higher energy collisions later this year.

That`s just one of the reasons Chunhui Chen, Prell and Cochran`s colleague, is telling people that big, new, Nobel-winning physics from the LHC won`t happen right away. There`s just too much data to collect, distribute and analyse.