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Presented are the main design features of the large Cathode Strip Chambers (CSCs) for the CMS Endcap Muon System as well as the performance results obtained with the two full-scale 3.4×1.5 m2 six-plane prototypes. The prototype performance was within the baseline requirements: (a) higher than 99% efficiency of muon track finding at the trigger level with more than 92% probability for bunch crossing identification and better than 2 mm spatial resolution, and (b) better than 150 μm spatial resolution in off-line.

Presented are the main design features of the large cathode strip chambers (CSCs) for the CMS endcap muon system as well as the performance results obtained with the first large-scale prototype. The 3.4×1.2 m 2 six-plane prototype has been reliably operated over one year and the cosmic-ray tests showed that it was capable of detecting muons with ∼80 μm spatial and ∼5 ns time resolutions.

We report on the results of testing two six-layer 0.6 × 0.6 m 2 cathode strip chamber (CSC) prototypes in a muon beam at CERN. The prototypes were designed to simulate sections of the end-cap muon system of the Compact Muon Solenoid (CMS) detector which will be installed at the Large Hadron Collider (LHC). We measured the spatial and time resolutions of each chamber for different gains, different orientations with respect to the beam direction and different strength magnetic fields. The single-layer spatial resolution of a prototype with a strip pitch of 15.88 mm ranged from 78 to 468 μm, depending on whether the particle passed between two cathode strips or through the center of a strip; its six-layer resolution was found to be 44 μm. The single-layer spatial resolution of a prototype with a strip pitch of 6.35 mm ranged from 54 to 66 μm; its six-layer resolution was found to be 23 μm. The efficiency for collecting an anode wire signal from one of six layers within a 20 ns time window appropriate for the LHC was found to be greater than 95% in normal running conditions.

This report describes the 1991 implementation of the data acquisition system of the OPAL detector at LEP including the additional services and infrastructure necessary for its correct and reliable operation. The various tasks in this “on-line” environment are distributed amongst many VME subsystems, workstations and minicomputers which communicate over general purpose local area networks and special purpose buses. The tasks include data acquisition, control, monitoring, calibration and event reconstruction. The modularity of both hardware and software facilitates the upgrading of the system to meet new requirements.

A silicon strip microvertex detector has been designed, constructed and commissioned in the OPAL experiment at the LEP electron-positron collider. The microstrip devices incorporate a new FoxFET biassing scheme developed together with Micron Semiconductor Ltd., UK. The devices digitise with a precision close to 5 μm and have an exceptionally high signal-to-noise ratio. The associated microelectronics were all custom made for the OPAL project. The detector began operation in 1991 and has since continued to be part of the OPAL experiment, performing to a very high standard and opening up new areas of physics studies.

We measured electron shower transport through a finely granulated calorimeter composed of alternating layers of aluminum and plastic scintillator for electron energies of 53, 108 and 144 MeV. These data were in the transition region near to the critical energies for both aluminum and carbon. Previous measurements in this region suggested deviations from the predicted calorimeter energy resolution; however, our data were in agreement with resolutions calculated using the EGS4 computer program. We made detailed measurements of the penetration depth of electrons and their electromagnetic showers into the calorimeter, as well as the size of gaps where the energy was transported by neutral particles. These measurements were also found to be in general agreement with the EGS4 predictions. However, there was one significant discrepancy, the data showed significantly deeper shower penetration into the calorimeter than predicted by the program.