Phase Locking the Spin Precession in a Storage Ring

Abstract

This Letter reports the successful use of feedback from a spin polarization measurement to the revolution frequency of a 0.97 GeV/c bunched and polarized deuteron beam in the Cooler Synchrotron (COSY) storage ring in order to control both the precession rate (≈121 kHz) and the phase of the horizontal polarization component. Real time synchronization with a radio frequency (rf) solenoid made possible the rotation of the polarization out of the horizontal plane, yielding a demonstration of the feedback method to manipulate the polarization. In particular, the rotation rate shows a sinusoidal function of the horizontal polarization phase (relative to the rf solenoid), which was controlled to within a 1 standard deviation range of σ=0.21 rad. The minimum possible adjustment was 3.7 mHz out of a revolution frequency of 753 kHz, which changes the precession rate by 26 mrad/s. Such a capability meets a requirement for the use of storage rings to look for an intrinsic electric dipole moment of charged particles.

Nuclear electric dipole moment in the cluster model with a triton: Li7 and B11

“…In this work, we focus on the nuclear EDM which may be measured using storage rings [15,17,[56][57][58][59][60][61]. Although the idea is not new, this approach is currently being developed, and the experimental preparation is on-going [62][63][64][65]. * ynodoka@yukawa.kyoto-u.ac.jp Let us list the advantages of the nuclear EDM.…”

Phase measurement for driven spin oscillations in a storage ring

“…115 s after the start of the cycle, at turn number 22.9 × 10 6 , the solenoid was switched on again while the feedback system was switched off, allowing the spins to precess independently from the solenoid. This is the important difference from the procedure described in [4], where the feedback system remained active for the whole cycle. The experiment was repeated for 16 values of Δϕ 0 between −π and π.…”

“…An analytical model is derived, which is compared to the data. The work is based on earlier publications; it makes use of the 1000 s spin coherence time at the Cooler Synchrotron (COSY) [1], measurements of the fast (120 kHz) precession in the horizontal plane [2,3] and a polarization feedback system, which is used to select the initial conditions for the measurements presented here [4].…”

“…The presented experiment was performed at COSYunder conditions similar to those described in [4]. A deuteron beam with a vertical vector polarization was injected into COSY and accelerated to a momentum of 970 MeV=c.…”

Non-exponential decoherence of radio-frequency resonance rotation of spin in storage rings

“…Inherent to particles in storage rings is a modulation of the spin-tune by synchrotron oscillations (SO) which drives the spin precession and RF frequencies apart [4] and decoheres evolution of the polarization of particles in an ensemle. It becomes still more important at large spin rotation times imperative in searches for extremely small EDM's [5,6,7]. In this paper we develop a fully analytic theory of SO driven spin decoherence and show that SOs entail a non-exponential attenuation of resonance driven up-down oscillations averaged over an ensemle.…”