Spin Dynamics Investigation of Quasi-Frozen Spin Lattice for EDM Searches

TL;DR

This paper explores the Quasi-Frozen Spin (QFS) method as a simplified alternative to the Frozen Spin technique for deuteron EDM searches, demonstrating its viability through modeling and tracking in the COSY ring.

Contribution

It introduces a new implementation approach for QFS in the COSY ring, including calibration and systematic error mitigation, supported by detailed modeling and simulation results.

Findings

QFS is a viable alternative to FS for EDM searches

Modeling shows QFS can be implemented with minor modifications to existing rings

Tracking indicates manageable systematic errors in QFS approach

Abstract

The Quasi-Frozen Spin (QFS) method was proposed by Yu. Senichev et al. in [1] as an alternative to the Frozen Spin (FS) method [2] for the search of deuteron electric dipole moment (dEDM). The QFS approach simplifies the design of the lattice. In particular, small changes to the currently operating COSY storage ring will satisfy the QFS condition. Spin decoherence and systematic errors fundamentally limit EDM signal detection and measurement. Our QFS implementation method includes measurement of spin precession in (1) the horizontal plane to calibrate the magnetic field when changing field polarity and (2) the vertical plane to search for EDM. To address systematic errors due to element misalignments, we track particle bunches in forward and reverse directions. We modeled and tracked two QFS and one FS lattice in COSY INFINITY. The models include normally distributed random variate spin kicks in magnetic dipoles and combined electrostatic and magnetic field elements. We used Wolfram Mathematica programs to partially automate lattice input file generation and tracking output data analysis. We observed indications that the QFS method is a viable alternative to the FS method. [1] Y. Senichev, A. Lehrach, B. Lorentz, R. Maier, S. Andrianov, A. Ivanov, S. Chekmenev, M. Berz, and E. Valetov (on behalf of the JEDI Collaboration), in Proceedings of IPAC 2015, Richmond, VA (2015) MOPWA044. [2] D. Anastassopoulos et al., AGS Proposal: Search for a Permanent Electric Dipole Moment of the Deuteron Nucleus at the $10^{-29}\:e\cdot\mathrm{cm}$ Level, BNL Report, Brookhaven National Laboratory, Upton, NY (2008).