SQUID-based beam position monitor

Abstract

The proton electric dipole moment (pEDM) experiment is proposed to be done with two counter-rotating beams in an all-electric storage ring. Radial magnetic field is one of the most critical systematic errors in the experiment as it mimics the EDM signal. Its secondary effect is a vertical split between the counter-rotating beams. According to the proposal of the pEDM experiment, that split should be monitored and compensated to picometer level by the beam position monitoring systems (BPM). We propose a BPM using Superconducting QUantum Interference Devices or SQUIDs to measure the beam splitting with such resolution that corresponds to magnetic field measurement with 10−18 T (aT) resolution. In this paper we experimentally demonstrate that the white noise of such magnetometers and SQUID read-out electronics can be decreased by more than two orders of magnitude down to 25 aT/√Hz by using 5 hour signal averaging. It demonstrates very high long-time stability and low intrinsic fluctuation level in the instrument. We expect that our next BPM version will be able to reach [removed]