Oxford DELPHI Detector

Barrel Muon Detector

Oxford was responsible for the design and construction of the 1372 drift chambers which form the Barrel Muon Identifier. All chambers were built and tested in Oxford. The assembly into planks of 7 or 14 chamber was done by RAL, who also collaborated in the installation. All of the front end electronics was built in Oxford.

The system has worked well since its installation and is 98% efficiency for data taking. The performance of the detector is according to specification. During the entire data taking period the muon chambers participated in the first and second level triggers. After readout the third level trigger processor acts on the recorded data and results in the elimination of 25% of spurious triggers.

Surround Muon Chambers

As a result of studies carried out in 1992 it was decided to complete the DELPHI muon identifier by providing cover in the 45 degree region between the barrel and end caps. In view of Oxford's experience and interest in this area we provided the readout strip planes of laminated copper on a honeycomb support for the detector, which consists of limited streamer tubes, similar to those in the Hadron Calorimeter. In addition Oxford, in collaboration with Belgian groups, provided analysis and simulation software for the new detector, based on existing end cap and barrel muon programs. The major financial support for the SMC was provided by Czech, Finnish and Russian groups. This detector was installed during the 1993/94 shutdown.

The Microvertex Detector

The DELPHI microvertex detector has been in operation since 1990, and the present 3-layer detector has produced some remarkable results. It was planned, for the start of LEP physics running in 1993, to upgrade the detector. The close (radius 6.3 cm) and outer (radius 10.9 cm) layers of the three-layer single-sided device implemented at present, were replaced by double-sided microstrip silicon detectors with mutually orthogonal read-out lines capable of a 10 micron precision in both the R-phi and Z planes. The work of the Oxford/DELPHI group was concerned with all aspects of checking and assimilating the performance of the closer layer and a proportion of the outer layer detector `modules' prior to their installation in DELPHI.