✍ Scribed by R. Chritin; D. Cornuet; B. Dehning; A. Hidalgo; M. Hildreth; W. Kalbreier; P. Leclère; G. Mugnai; J. Palacios; F. Roncarolo; E. Torrence; G. Wilkinson
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The LEP spectrometer performed calibrations of the beam energy in the 2000 LEP run, in order to provide a kinematical constraint for the W boson mass measurement. The beam was deflected in the spectrometer by a steel core dipole, and the bending angle was measured by Beam-Position Monitors on either side of the magnet. The energy determination relies on measuring the change in bending angle when ramping the beam from a reference point at 50 GeV to an energy within the LEP W physics regime, typically 93 GeV. The ratio of integrated bending fields at these settings (approximately 1.18 Tm/0.64 Tm) must be known with a precision of a few 10 À5 :
The paper reports on the field mapping measurements which were conducted to determine the bending integral under a range of excitation currents and coil temperatures. These were made in the laboratory before and after spectrometer operation, using a test-bench equipped with a moving arm, carrying an NMR probe and Hall probes, and in the LEP tunnel itself, with a mapping trolley inside the vacuum chamber. The mapping data are related to local readings supplied by fixed NMR probes in the dipole, and a predictive model developed which shows good consistency for all datasets within the estimated uncertainty, which is 14 Â 10 À5 for the moving arm, and 3 Â 10 À5 for the mapping trolley. Measurements are also presented of the field gradient inside the dipole, and of the environmental magnetic fields in the www.elsevier.com/locate/nima
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LEP measurements of the weak electric dipole moment d~ and the weak anomalous magnetic dipole moment a~' of the r lepton are reviewed and the search for CP violation in the production of r pairs on the Z peak is discussed. Two methods of the measurement of the weak dipole moments based on the analys