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 3He) to search for an intrinsic electric dipole moment
(EDM) aligned along the particle spin axis. Statistical sensitivities could approach
10-29e cm. The challenge will be to reduce systematic errors to similar levels. The ring
will be adjusted to preserve the spin polarization, initially parallel to the particle velocity,
for times in excess of 15 min. Large radial electric fields, acting through the EDM, will
rotate the polarization from the longitudinal to the vertical direction. The slow increase in the
vertical polarization component, detected through scattering from a target, signals the EDM.
The project strategy is outlined. A stepwise plan is foreseen, starting with ongoing COSY
activities that demonstrate technical feasibility. Achievements to date include reduced polarization
measurement errors, long horizontal plane polarization lifetimes, and control of the
polarization direction through feedback from 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 a high-precision electric-field storage ring.
CERN Yellow Reports: Monographs, 3 (2021) CERN-2021-003.
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