Design of a Magnetic Quadrupole Pick-up for the CERN PS

A quadrupole pick-up is sensitive to the quantity $\sigma_x^2 - \sigma_y^2$ where $\sigma_x$ and /sigma_y$ are the horizontal and vertical r.m.s. beam sizes. Since it is a non-invasive device, it is potentially very useful for matching and emittance measurements. A magnetic quadrupole pick-up developed for the CERN PS. By coupling to the radial component of the magnetic field around the beam, it was possible to eliminate the common-mode problem, which is usually a limiting factor in the use of quadrupole pick-ups. This paper presents the final pick-up design, which is the result of a series of simulations and test prototypes. The performance of the pick-up and its associated electronics is discussed. Preliminary results from the two pick-ups recently installed in the PS machine are also presented.