In the CMS detector project, the entire forward muon system, both detectors and absorber, is considered to be primarily an American effort. The CMS management structure now reflects this situation in that the Project Manager of the forward muon system and the great majority of the institutions involved are in the U.S. Direct responsibility for the design and construction of this well defined part of the CMS detector will reside here, although there will be other international contributors to the project.
Muon detection in the forward region has been the responsibility of American groups from the inception of the CMS project. The four American groups already present on the CMS LoI, UC Davis, UCLA, UC Riverside, and UT Dallas, in collaboration with a contingent from Dubna, elaborated a conceptual design involving cathode strip chambers (CSCs) for this region. The CSC technology is the best candidate for the forward muon detection system, because such chambers are able to function in a high magnetic field and in the presence of a high particle rate. CSCs are fast, with an electron drift time on the order of the beam crossing interval, so that they can combine all necessary functions of the muon system-position measurement, timing, and triggering-in a single detector.
In choosing an appropriate project, these original groups sought a detector element which was important in the overall CMS design strategy, with its emphasis on muons, and whose design and implementation represented a certain challenge for the physicists involved. This remains the case, even as the American participation in CMS has been broadened to include other areas. The addition of groups and individuals from the GEM Collaboration brings considerable expertise in the technology of CSCs, since this was the GEM baseline design. Also, questions of mechanical support and alignment have been studied in great detail by other GEM and SDC groups which have now joined CMS. The American groups now form a team which is very capable of handling the challenges of the CMS forward muon system and of giving the US HEP community a significant participation in LHC physics.
Many of the groups involved in the muon system are already participating in the RD5 experiment at CERN. During this coming summer R&Defforts there will address the problem of Lorentz angle compensation in a perpendicular magnetic field. Work in the US will focus on aspects of the construction and behavior of large chambers, with wider gaps and coarser strip spacing. Details of strip configuration will also be explored, mainly by calculation and simulation, but perhaps also by prototyping. Extensive simulation work is necessary as well in the area of pattern recognition. Front end readout electronics that can work in the pipeline mode must be developed. An effort is also planned on the use of RPCs operating in avalanche mode as a redundant trigger integrated into the forward muon system. Finally some prototyping of the endcap iron structure must be carried out.
List of Interested Groups: