The Tracker's Midnight Ride
The CMS tracker gets used to it's new home. Image courtesy of Michael Hoch, Adventure Art.
Under a starry sky just before midnight on Dec. 12, a truck carrying the CMS experiment's silicon tracker pulled out of the main CERN site. It began its 10-mile voyage to the underground experiment hall for the CMS detector. At 1:30 a.m. on Dec. 16 the team of scientists bolted the tracker into place.
The silicon tracker comprises 10 million silicon strips that will detect particles created in the LHC's proton collisions, and specialized electronics to select and send data to computers for storage and analysis.
"The silicon strip detector operates like a high-speed camera capable of taking 40 million images of elementary particles each second," said Slawek Tkaczyk of Fermilab, leader of the tracker electronics team.
The tracker's journey across the LHC-ring took three hours. "This was like having their baby crawl to CMS," said Joel Butler said of Fermilab, U.S. CMS project manager. "When it got there, you could see the relief of everyone involved."
At 2:30 p.m. on Dec. 13, the tracker began its 260-foot descent. Motion sensors monitored shaking to prevent damage to the detector. By 3:05 p.m., it rested safely on the cavern floor.
The next morning, Dec. 14, a team hoisted the tracker to align it with the detector. Next on Dec. 15, technicians stripped off its seal and introduced it into CMS. By 1:30 a.m. Dec. 16, scientists secured the tracker in place and toasted with champagne.
"This is a major milestone for CMS, marking the completion of the silicon tracker and the completion of the central CMS detector," said Jeff Spalding of Fermilab, co-leader for the final integration of the silicon tracker. "It is also a major personal milestone for the many U.S. physicists, engineers and technicians who worked on the project."
The silicon tracker group is eager to connect the tracker to the cooling and electronics at CMS in January and to commission full system ready for physics. The successful installation of the tracker in its new home brings CMS that much closer to the first proton collisions in mid-2008.