Rotating coil system for ILC final focus magnet quadrupole. Part 2

Quadrupole magnets for ILC final focus should be strong enough with the restriction on the external radius to let the disrupted out-going beam pass by, while vibration of the magnetic center has to be highly avoided to keep the nm sized beam focusing stable at the interaction point a few meter downstream from the lens. Gluckstern's 5-ring PMQ singlet seems a good candidate for this point of view. In order to fabricate a good 5-ring singlet, property of each ring has to be good enough. A precise magnetic field measurement system for harmonic components is needed for adjustments of relative positions and angles of magnet pieces in a ring. A rotating coil system, which has 24-bit ADCs for higher resolution, is developed. We calibrated the system with 2D mapping results of dipole and quadrupole of PM by hall probe and evaluated statistical error. (author)