LHC experiments reach record data milestone
|The ATLAS and CMS experiments have both accumulated 1 inverse femtobarn of data, an important milestone for both experiments. Image courtesy of CERN.
As of this week, the Large Hadron Collider has delivered one inverse femtobarn of integrated luminosity to ATLAS and CMS, two of the four experimental stations housed along the ring. This means the detectors will have gathered data from about 100 trillion proton-proton collisions. For comparison, the experiments collected just 45 inverse picobarns in all of 2010; one inverse femtobarn is equal to one thousand inverse picobarns.
Accelerator scientists promised one inverse femtobarn for the entire 2011 run, but met their goal just a few months after collisions began in March. The groups could see several more inverse femtobarns by the end of the year.
Scientists wasted no time analyzing the first few hundred inverse picobarns, and announced their findings at the Physics at LHC conference last week. With five times more data than they had in 2010, researchers have been able to set more stringent limits on new physics. They haven’t observed anything new just yet, but are beginning to explore uncharted territory.
“We spent 2010 rediscovering the Standard Model,” said Richard Hawkings, the deputy physics coordinator for the ATLAS experiment. “In 2011, we will push our detectors to the limit and make more precise measurements.”
Experimentalists have increased the sensitivity of the detectors to Standard Model processes, the events that account for much of the background signal in the hunt for new physics. Making the most precise measurements of these events could lead to an indirect hint of something new.
For example, the number of single top quarks scientists have spotted agrees well with what is predicted by the Standard Model, but with the new data they can begin to study the behavior between the top quark and the other, lighter quarks.
Despite finding no direct evidence of new physics, Hawkings says they have made significant inroads toward a discovery. “We’re closing in on supersymmetry,” he said. The data suggest that some of the theorized superparticles must have masses greater than 1 TeV, which narrows the window for observation. “We’ve looked through a lot of the space where supersymmetry could have been found, but there are still more corners to explore,” Hawkings said.
— Lauren Rugani