LEP operation in 1992 with a 90/spl deg/ optics

The optics for physics operation in LEP was changed from 60/spl deg/ to 90/spl deg/ at the start of 1992 with a view to improved Z/sup 0/ production, preparation for future operation at higher energies and the use of the same optics in machine developments. The developments included running LEP with twice the number of bunches and using resonant depolarisation for energy calibration, Perturbation to steady operation was felt at the start of the year but was soon overcome as the benefits of smaller emittances were realised. The peak luminosity increased to 1.15 10/sup 31/ and the luminosity lifetime improved. New operational software halved the time taken between dumping one coast and the start of data taking on the next. The 8+8 bunch operation was introduced as routine operation for the last month. Overall, there was an increase in integrated luminosity from 17.6 inverse picobarns per experiment in 1991 to 28.6 in 1992. Along with improvements in detector efficiency, almost 3 million hadronic Z/sup 0/s were recorded by the four experiments, an increase from 1.27 million in 1991.<
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