Towards a more sensitive measurement of the permanent electric dipole moment of Radium-225

Ra-225 is expected to have a greatly enhanced sensitivity to its permanent atomic electric dipole moment (EDM) arising from violation of combined charge-conjugation (C) and parity (P) transformation, and, assuming CPT symmetry, time (T) violation due to its octupole-deformed nucleus. A proof-of-principle measurement of the upper limit of the Ra-225 EDM was carried out in 2014 (PRL 114 233002) and an improved measurement followed in June 2015 (PRC 94 025501). There are three main experimental upgrades that can collectively contribute to a much more sensitive EDM measurement. This work updates the status of the electric field upgrade. Radium atoms are vaporized, trapped, and transported into a science chamber with controlled magnetic and electric fields between two high voltage electrodes in the Ra EDM experimental apparatus at Argonne National Laboratory (ANL). Recently, a new pair of niobium electrodes was conditioned and validated at Michigan State University (MSU) and installed in the apparatus, replacing the original electrodes.