Betatron function measurement at LEP using the BOM 1000 turns facility

A new method for measuring the beta function around LEP is presented. The method uses phase difference measurements between three adjacent beam position monitors to obtain the value for the beta function at the monitors and in their neighbourhood, e.g. at interaction points, electrostatic separators etc. The phase differences are obtained from measuring coherent betatron oscillations for 1024 turns at the 504 beam position monitors. After a discussion of the accuracy of the method the measured values for the beta function are compared with the theoretical values for different lattices. In regular parts of the lattice (e.g. arcs) the beating of the beta function measured using this method agrees well with the beating obtained by another method using a fit of the phase over 15 monitors