Pilot bunch and co-magnetometry of polarized particles stored in a ring

TL;DR

This paper introduces a method using a pilot bunch as a co-magnetometer in storage rings to monitor and compensate for magnetic field fluctuations, enhancing precision in spin-resonance experiments.

Contribution

The paper presents a novel shielding technique that allows a pilot bunch to serve as a real-time co-magnetometer, improving control of spin precession in storage ring experiments.

Findings

Successfully demonstrated shielding of a pilot bunch from high-frequency fields.

The pilot bunch effectively tracked magnetic fluctuations on a one-second timescale.

Potential applications in electric dipole moment searches and future spin physics facilities.

Abstract

In polarization experiments at storage rings, one of the challenges is to maintain the spin-resonance condition of a radio-frequency spin rotator with the spin-precessions of the orbiting particles. Time-dependent variations of the magnetic fields of ring elements lead to unwanted variations of the spin precession frequency. We report here on a solution to this problem by shielding (or masking) one of the bunches stored in the ring from the high-frequency fields of the spin rotator, so that the masked pilot bunch acts as a co-magnetometer for the other signal bunch, tracking fluctuations in the ring on a time scale of about one second. While the new method was developed primarily for searches of electric dipole moments of charged particles, it may have far-reaching implications for future spin physics facilities, such as the EIC and NICA.