World's Largest Particle Detector Nearing Completion, Penn Physicists Prepare To Study Nature of Matter

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Media Contact:Jordan Reese | | 215-573-6604February 29, 2008

PHILADELPHIA -- Today, researchers at the University of Pennsylvania and their U.S. ATLAS collaborators joined colleagues around the world to celebrate a pivotal landmark in the construction of the Large Hadron Collider (LHC) – the lowering of the final piece of the ATLAS particle detector into the underground collision hall at CERN in Geneva, Switzerland.

Experiments conducted at this revolutionary LHC facility, poised to become the world’s most powerful particle accelerator, may help scientists unravel some of the deepest mysteries in particle physics. Penn particle physicists Brig Williams, Evelyn Thomson and Joe Kroll, together with graduate students, postdoctoral fellows and technical staff at Penn, have a strong participation in the ATLAS experiment. Members of this group, together with collaborators in Europe and the United States, designed and commissioned the 350,000 electronic circuits for a tracking detector that will eventually provide images of the 40 million proton collisions that occur every second. This tracking detector was installed in the experimental cavern 100 meters underground during June 2007 and has since been undergoing extensive testing by Penn personnel.

Today, the last piece of ATLAS lowered into the ATLAS experimental cavern is one of two elements known as the small wheels. The two ATLAS small wheels are each about 30 feet in diameter and weigh 100 tons. It is the detectors on each wheel that will be used to identify and measure the momentum of subatomic particles, called muons, that are created in collisions at the LHC. The entire detector system has an area equal to three football fields, consisting of 100 million independent electronic channels. As charged particles pass through a magnetic field created by superconducting magnets, this detector has the ability to accurately track them to the precision of the width of a human hair.

“This is more than just a proud moment for the physics community, this is a milestone marking one of the great collaborations in science,” said Brig Williams professor in the Department of Physics and Astronomy at Penn. “For Penn this is the culmination of a decade of intense research to produce a critical component of the ATLAS detector. We look forward to using ATLAS to explore the fundamental forces in the universe when proton-proton collisions begin at the LHC later this year.

“We’re proud of the teams involved in this international scientific endeavor - one of the largest collaborative efforts ever attempted in the physical sciences,” said Dennis Kovar, acting associate director for High Energy Physics in DOE’s Office of Science. “This technical landmark brings us a huge step closer to unveiling a new level of understanding of our universe.”

Of the almost 2,100 participants in the ATLAS collaboration, about 420 are U.S. physicists, engineers, and graduate students hailing from 38 universities and four national laboratories. Involving the work of 450 physicists from 48 institutions around the world, lowering this last small wheel marks the end of a decade of planning and construction of the muon spectrometer system.

“These fragile detectors comprise the largest measuring device ever constructed for high-energy physics,” said George Mikenberg, ATLAS muon project leader.

Experiments at the LHC will allow physicists to take a big leap in their exploration of the universe. The ATLAS detector may help its scientists unravel some of the deepest mysteries in particle physics such as the origin of mass or the identification of dark matter. The ATLAS collaboration will now focus on commissioning the detector in preparation for the start-up of the LHC this summer.

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