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The Central Tracking Detector of the ZEUS experiment employs a time difference technique to measure the z coordinate of each hit. The method provides fast, three-dimensional space point measurements which are used as input to all levels of the ZEUS trigger. Such a tracking trigger is essential in order to discriminate against events with vertices lying outside the nominal electron-proton interaction region. Since the beam crossing interval of the HERA collider is 96 ns, all data must be pipelined through the front-end readout electronics. Subsequent data aquisition employs a novel technique which utilizes a network of approximately 120 INMOS transputers to process the data in parallel. The z-by-timing method and its data aquisition have been employed successfully in recording and reconstructing tracks from electron-proton interactions in ZEUS. © 1993.

The Vertex Drift Chamber for the OPAL experiment at LEP provides high quality track coordinates using multihit subnanosecond timing to detect the drifted electrons. This paper explains the electronic techniques that have been devised and implemented for the detector. The overall performance of the system is demonstrated with measurements from the final OPAL chamber.

Summary form only given. Subsea cable technology has advanced to allow the manufacture of both single and three core cables for bulk power transfer between transmission systems in continuous lengths up to 100 km. The mechanical and electrical integrity of these cable systems is enhanced by the ability to manufacture the cable in long lengths, thereby removing discontinuities at jointing positions. Handling of long length cables is complex, requiring manufacturing facilities capable of insulating, sheathing, armouring, storing and off-loading the cable to be located on the same site. A 100 km continuous length of completed, armoured cable for example may weigh in excess of 8000 Tonnes. The installation of subsea cable presents many challenges in mechanical and marine engineering. The cable must withstand the significant mechanical forces which are generated during installation due to its own weight and the action of tidal currents. The installed cable is also at risk from damage by anchors, fishing activity, vessel impact, movement of the cable or seabed terrain. To protect the cable during laying or in service metallic armour wires are applied in one or two layers to the construction as part of the manufacturing process, however, additional protection can be offered by burying the cable in the seabed using a variety of jetting, ploughing or trenching techniques. The paper describes the choice of cable design which exists for subsea power links and the merits of these various designs. The manufacture and installation of long continuous lengths of subsea power cable is discussed with reference to some key installations.

A method to determine the z-coordinate of a track using a time-difference measurement has been developed for the ZEUS Central Tracking Detector. It has been demonstrated that a spatial resolution of 50 mm can be obtained under normal chamber operating conditions. This corresponds to a time-difference resolution of 330 ps. A method of minimizing nonlinearities in the time-to-distance response is described. This uses an inductor to form a matching network to achieve resistive termination of the chamber. Test beam measurements from a prototype chamber are presented, demonstrating the effects of the chamber surface field and beam incidence angle on the time-difference resolution.