Capping off installation

Installation of the cathode strip chambers for the muon system on the CMS positive endcap has been completed.

Like successfully putting together the pieces of a giant puzzle, installation of the muon system cathode strip chambers on one of the CMS endcaps has been completed. Total installation of the cathode strip chambers (CSC) is now 91 percent complete; only one ring of chambers needs to be mounted on the remaining endcap to finish installation of the entire system.

To guarantee a good fit for the 468 total endcap muon system CSCs, physicists and engineers from the collaboration spent about 10 years carefully planning the design. The endcap muon system's cables, boxes, pipes and other parts were designed and integrated using a 3D computerized model. 'It took a long time to do all the computer modelling, but in the long run it saved us an enormous amount of time because it meant that everything fit together,' said Project Manager Dick Loveless. 'We didn't have to do a lot of stuff here at the last minute.' After the design was complete, quality control was key. Most of the chamber's parts were made in the United States and then put together at U.S., Russian and Chinese institutions.

'The CMS detector is one of the first to use CSCs on such a large scale', said Richard Breedon, a research physicist from the University of California, Davis, who is working on the CSC project. With four CSC stations on each endcap and six layers in each chamber, Breedon said he believes the robust design will succeed. 'Triggering on muons in the endcap in a hadron machine has always been very challenging,' he said. 'We're hoping we have learned from the experience of other detectors that have tried it.'

The first chambers were installed in June 2003, and CSC installation on the first endcap was finished in early February. The remaining CSCs will be installed following the CMS magnet test this summer. After chambers are mounted, a team installs the 6000 cables necessary for operation and attaches services such as gas and high voltage. Next, a commissioning team turns on the chambers and electronics to test their performance. About 85 percent of installed chambers have been tested and, so far, the results have been encouraging. Not one of the 2 million or so wires used in the system has been found to be broken.