Author/Authors :
Arnaudon، نويسنده , , L. and Dehning، نويسنده , , B. and Hofmann، نويسنده , , A. and Grosse-Wiesmann، نويسنده , , P. and Jacobsen، نويسنده , , R. and Koutchouk، نويسنده , , J.P. and Miles، نويسنده , , J. and Olsen، نويسنده , , R. and Placidi، نويسنده , , M. and Schmidt، نويسنده , , R. and Wenninger، نويسنده , , J. and Assmann، نويسنده , , R. and Blondel، نويسنده , , A. and Fischer، نويسنده , , G.E.، نويسنده ,
Abstract :
The circular e+e− collider LEP located near Geneva is used to investigate the properties of the Z boson. The measurements of the Z boson mass and resonance width are of fundamental importance for the standard model of the electroweak interactions. They require a knowledge of the LEP beam energy with a precision of ∼ 20 ppm, which is provided by a measurement of the electron spin precession frequency. To extrapolate beam energy calibrations over a longer period of time, effects causing energy changes have to be taken into account. Among these are the terrestrial tides due to the sun and moon which move the Earth surface up and down. The lateral components of this motion modify the 26.7 km LEP circumference by about 1 mm. This change in length results in variations of the beam energy up to 120 ppm. We present results of measurements on the influence of terrestrial tides on the LEP beam energy that have been performed in 1992 and 1993.
