Measurements of noise on the PS B-train’s B-dot signal

This note reports the results of a series of magnetic field measurements carried out in the PS reference magnet U101 in February 2011, aimed at investigating the source of an abnormally high noise on the B-dot signal noticed by operation. Results indicate that the noise can be ascribed to actual field perturbations which may be traced back to power converter ripple. Due to the filtering effect of the magnet, however, the perturbations are very small i.e. generally less than 0.1 G above 1 kHz, which is unlikely to represent a serious beam disturbance.