Electric and magnetic field control for electric dipole moment searches
Permanent Electric Dipole Moments (EDMs) would violate the symmetries of parity and time-reversal, and with validity of CPT symmetry they would also violate the combined CP symmetry. EDMs have been suggested in many speculative extensions to the Standard Model of particle physics. The purpose of the NL-eEDM experiment is to search for a permanent electron Electric Dipole Moment (eEDM). The experiment entails a BaF molecular beam moving through an interaction zone with a homogeneous electric and a homogeneous magnetic field. A non-zero eEDM would reveal itself in a different spin precession behavior for parallel and anti-parallel electric and magnetic fields.
The emphasis of this work lies on the design, implementation, evaluation and use of the interaction zone for this new experiment. The design is informed by calculations with COMSOL software. The implementation consists of Indium Tin Oxide (ITO) coated glass plates for homogeneous electric field generation at several kV/cm scale. A homogeneous magnetic field of O(nT) is realized by a novel designed double cosine coil, which resides in a 5 layer µ-metal shield with O(10^6) shielding surrounded by rectangular compensation coils.
This work in combination with work on a BaF source, laser systems, a quantum mechanical description of the measurement process, data acquisition and analysis provides the first complete eEDM setup at the VSI in Groningen. Measurements have been performed with spin precession on BaF molecules in order to quantify the capabilities of the setup. These show that the setup of the interaction zone suffices for a competitive eEDM search.