Energy Calibration with Energy Loss Measurements

by Anke-Susanne Mueller (CERN)

Thursday 9 Dec 1999, 16:00 → 16:15 Europe/Zurich

SL Auditorium (CERN)

The measurement of the W Boson mass at LEP2 requires a determination of the beam energy with the highest possible accuracy. Present schemes for energy calibration above the W+W- threshold of 80 GeV are based on extrapolations of resonant depolarization measurements to high energy. Since such extrapolations involve systematic uncertainties, alternative methods have been studied which are based on measurements of the energy loss due to synchrotron radiation. Because this energy loss increases with the fourth power of energy, observable sensitive to the energy loss per turn can be used to determine the beam energy. Three different methods to measure the energy loss have been studied. The first technique is based on the analysis of electron positron difference orbits, the second on measurements of the damping of horizontal coherent oscillations after an excitation and the last one on studies of the relation between synchrotron tune Qs and total accelerating voltage. As a side product, the analysis of the damping of coherent oscillations gives an opportunity to measure the horizontal detuning with amplitude (anharmonicity) which is an important parameter for the understanding of the dynamic aperture of storage ring optics. This talk will focus on the description of the different approaches to the energy loss measurement and discuss advantages and disadvantages of the methods.

Organiser(s): Werner Herr / SL Division

Note: Tea and coffee will be served at 15:30 in front of the Auditorium

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