Tickling C:AQ5

The alignment of the quadrupoles in a proton synchrotron is important and the alignment of the low beta quadrupoles in collider mode is even more critical. One of the important considerations is the relationship of the electric center of the Beam Position Monitors (BPMs) to the magnetic center of quadrupoles. Determining this involves measurements when the elements are not in the tunnel and careful alignment utilizing external reference marks when the BPMs are not physically attached to the quadrupole. Even when the BPM is attached to the quadrupole (and calibrated), systematic offsets can be introduced by cable mismatch or slight imbalances in the monitoring electronics. A method has been implemented at Cern [1,2] to determine this relationship using the beam itself. TM-1960 described a proof of principle experiment at the Tevatron using one of the individually powered quadrupoles near the B0 interaction region whose ACNET name is C:AQ7. This short note demonstrates that they can perform the same analysis on a set of quadrupoles powered by a single power supply without having to worry about exciting a single quadrupole.