High precision fundamental physics experiments using compact spin-transparent storage rings of low energy polarized electron beams

We present a new design of highly specialized small storage rings for low energy polarized electron beams. The new design is based on the transparent spin methodology that cancels the spin precession due to the magnetic dipole moment at any energy while allowing for spin precession induced by the fundamental physics of interest to accumulate. The buildup of the vertical component of beam polarization can be measured using standard Mott polarimetry that is optimal at low electron energy. Systematic effects are suppressed using counter-rotating bunched beams with various polarization orientations. These rings can be used to directly measure the permanent electric dipole moment of the electron, relevant to CP violation and matter-antimatter asymmetry in the universe, and to search for dark energy and ultra-light dark matter. & COPY; 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons .org /licenses /by /4 .0/). Funded by SCOAP3.

Automated summary

We propose a new design of small storage rings that are highly specialized for low energy polarized electron beams. This design eliminates spin precession caused by the magnetic dipole moment at any energy, while allowing for the accumulation of spin precession induced by the fundamental physics of interest. The rings can be used for direct measurement of the electron's permanent electric dipole moment, as well as for searching for dark energy and ultra-light dark matter.