Applications of the 1000-turns orbit measurement system at LEP

Abstract

The software of the LEP beam orbit measurement system allows the acquisition of the beam position for over 1000 consecutive turns. The acquisition can be synchronized to a deflection by a kicker in order to observe coherent betatron oscillations. In this paper we describe the use of this technique to study the dependence of head-tail damping on beam parameters and the tune dependence on the oscillation amplitude for various LEP optics. Coherent oscillations can be represented in phase space to observe the effect of resonances and other non-linear behavior. Coherent oscillations can also be excited using a sinusoidal deflection in order to maintain the oscillation amplitude. Thus, precise measurements of the phase advance are obtained by harmonic analysis of the signal at each pick-up.