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SLAC All Over the ATLAS

(Photo - ATLAS Pixel Detector)Thousands of scientific visitors regularly descend upon the European Organization for Nuclear Research (CERN). Home of the Large Hadron Collider (LHC), the newest and largest particle accelerator, makes CERN a frequent destination for visiting collaborators, many of whom are from SLAC.

"I end up spending more time at CERN than I do at SLAC," physicist Charlie Young said. "I wouldn't do all this traveling, if it weren't for the physics."

One particular center of SLAC's involvement at the LHC is the A Toroidal LHC ApparatuS (ATLAS) experiment, one of six detectors situated at collision interaction points. Nearly 2,000 ATLAS collaborators worldwide are busy finalizing the detector, which will scour data from the uncharted high-energy frontier.

In the LHC, billions of protons will collide 40 million times a second, but only about 200 of these events will be recorded. Clearly, scientists want to probe the most interesting interactions for the possibility of "new" physics. To separate the known from the unknown, SLAC physicists, along with others, have been programming trigger software that must quickly and accurately decide which data to keep or ignore.

SLAC scientists have also contributed to ATLAS's pixel detector. Deeply embedded within the core of the structure, the detector is uniquely suited for not only tracking the trajectories of particles, but pinpointing the origins of interactions.

As a whole, ATLAS works remarkably well, especially considering the complexity of its components and massive size. However, ATLAS collaborators are still working on numerous facets of the project. Other areas that SLAC is aiding the overall effort include detailed data simulations, which will include real data and data based on the best current approximations.

Matt Cunningham , SLAC Today, April 9, 2008

The pixel detector installed at the core of ATLAS will help track particles in the massive detector. (Photo: CERN)