Author: B. Dehning
Co-Author: G.P. Ferri, P. Galbraith, G. Mugnai, M. Placidi, F. Sonnemann, F. Tecker
Impact of Beam Based Alignment on Polarization at LEP
A beam based technique has been used at LEP to determine the offsets of beam position monitors (BPM) relative to the magnetic axis of the quadrupole magnets. Simulations show that the offsets are particularly important for the level of spin polarization achievable by so-called Harmonic Spin Matching, since it requires a precise knowledge of the vertical orbit kicks. The simulations indicate that polarization can be increased measuring the offsets of all BPMs in the arcs of LEP. The gain in polarisation is even significantly larger when the known mechanical quadrupole misalignments measured by the geometrical survey are included. It is envisaged to measure the offsets of all BPMs during the 1997 running period and the progress will be presented.