Synchrotron oscillation effects on an rf-solenoid spin resonance

Abstract

New measurements are reported for the time dependence of the vertical polarization of a 0:97 GeV=c deuteron beam circulating in a storage ring and perturbed by an rf solenoid. The storage ring is the cooler synchrotron (COSY) located at the Forschungszentrum Jülich. The beam polarization was measured continuously using a 1.5 cm thick carbon target located at the edge of the circulating deuteron beam and the scintillators of the EDDA detector. An rf solenoid mounted on the ring was used to generate fields at and near the frequency of the 1 À G spin resonance. Measurements were made of the vertical beam polarization as a function of time with the operation of the rf solenoid in either fixed or continuously variable frequency mode. Using rf-solenoid strengths as large as 2:66 Â 10 À5 revolutions=turn, slow oscillations ($ 1 Hz) were observed in the vertical beam polarization. When the circulating beam was continuously electron cooled, these oscillations completely reversed the polarization and showed no sign of diminishing in amplitude. But for the uncooled beam, the oscillation amplitude was damped to nearly zero within a few seconds. A simple spin-tracking model without the details of the COSY ring lattice was successful in reproducing these oscillations and demonstrating the sensitivity of the damping to the magnitude of the synchrotron motion of the beam particles. The model demonstrates that the characteristic features of measurements made in the presence of large synchrotron oscillations are distinct from the features of such measurements when made off resonance. These data were collected in preparation for a study of the spin coherence time, a beam property that needs to become long to enable a search for an electric dipole moment using a storage ring.

Electric dipole moments of atoms, molecules, nuclei, and particles

“…Several magnetometer schemes are feasible, and the most common are called M x magnetometers (Bell and Bloom, 1961;Bloom, 1962) and NMOR sensors (Pustelny et al, 2006). M x sensors monitor the Larmor frequency of atomic spins in a static field, e.g.…”

“…Results indicate that precision polarimetry for both deuterons and protons is feasible at the ppm level, which is required for a 10 −29 e · cm EDM sensitivity. Preliminary efforts to measure and improve spin coherence times of deuterons using the COSY storage ring have also been reported (Bagdasarian et al, 2014;Benati et al, 2012Benati et al, , 2013. High precision (10 −10 ) control and monitoring of the spin motion of deuterons at COSY has also been demonstrated (Eversmann et al, 2015).…”

Influence of electron cooling on the polarization lifetime of a horizontally polarized storage ring beam

“…A series of papers [1][2][3][4][5] from the cooler synchrotron COSY [6] show progress toward using a polarized beam in a storage ring to search for an electric dipole moment (EDM) on the charged particles in the beam. The signature of the EDM is the rotation of the beam's polarization, which is aligned with the EDM, about the radial direction in response to the torque produced by the particle-frame radial electric field [7].…”

Phase measurement for driven spin oscillations in a storage ring

“…The only possible initial state was upward or downward polarization. Additionally, the analytical model presented here is simpler than the numerical multiplication of rotation matrices used in the earlier publication [5].…”