Towards a More Sensitive Search for the Atomic EDM of Radium Using Laser Cooling and Trapping*

Searches for the atomic electric dipole moment (EDM) of diamagnetic atoms is primarily sensitive to charge-parity-(CP)-violation originating within the nuclear medium and are motivated by the observed and unexplained baryon asymmetry of the universe. The Radium-225 isotope, which has a two week half-life, has a large octopole ("pear-shaped") nuclear deformation which is expected to enchance its nuclear Schiff moment by about three orders of magnitude compared to the Hg-199 isotope which currently sets some of the best limits on new sources of CP-violation in the hadronic sector. The Ra EDM experiment utilizes laser probing to measure the spin precession of laser cooled and trapped atoms in its search for an EDM. A variety of upgrades for the experiment are underway which, when combined, are expected to improve the statistical sensitivity of the experiment by at least two orders of magnitude. A new laser cooling scheme, utilizing a stronger atomic transition, will increase the atom trapping efficiency by two orders of magnitude. In addition, a new high voltage apparatus capable of a factor of 7 higher electric field (E-field) as well as a more well-controlled E-field reversal is under development. A new laser-based spin-precession readout scheme, demonstrated recently for a similar search using Yb-171 atoms, is being adapted for Ra-225. Finally, studies are being performed, using stable surrogates, to quantify the efficiency of producing neutral atomic beams from rare isotopes harvested from the water beam dump at the Facility for Rare Isotope Beams, which will provide a new, abundant source of Ra-225 atoms.