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Storage Ring to Search for Electric Dipole Moments of Charged Particles -- Feasibility Study


The 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.

CPEDM Collaboration, CERN Yellow Reports: Monographs, 3 (2021) CERN-2021-003. DOI: 10.23731/CYRM-2021-003


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