Storage Ring to Search for Electric Dipole Moments of Charged Particles -- Feasibility Study
AbstractThe proposed method exploits charged particles confined as a storage ring
beam (proton, deuteron, possibly helium-3) to search for an intrinsic electric dipole moment
(EDM) aligned along the particle spin axis. Statistical sensitivities could approach
10-29 e cm. The challenge will be to reduce systematic errors to similar levels. The ring
will be adjusted to preserve the spin polarisation, initially parallel to the particle velocity,
for times in excess of 15 minutes. Large radial electric fields, acting through the EDM, will
rotate the polarisation from the longitudinal into the vertical direction. The slow rise in the
vertical polarisation component, detected through scattering from a target, signals the EDM.
The project strategy is outlined. It foresees a step-wise plan, starting with ongoing COSY
activities that demonstrate technical feasibility. Achievements to date include reduced polarisation
measurement errors, long horizontal-plane polarisation lifetimes, and control of the
polarisation direction through feedback from the scattering measurements. The project continues
with a proof-of-capability measurement (precursor experiment; first direct deuteron
EDM measurement), an intermediate prototype ring (proof-of-principle; demonstrator for
key technologies), and finally the high precision electric-field storage ring.
F. Abusaif et al., CERN-PBC-REPORT-2019-002, CERN (2019, update 2020)
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