Improvements of the Hg cohabiting magnetometer for the nEDM experiment

Full text: The Standard Model (SM) prediction for a static electric dipole moment for the neutron, breaking time reversal and parity symmetry is several orders of magnitude below the current best experimental limit dn < 2.9x10-26 e.cm (90 % CL). An experiment at the new ultra-cold neutron (UCN) source at the Paul Scherrer Institute, Switzerland, aims at a factor five improved sensitivity. Ramsey's method of separated oscillatory fields is used to detect a Larmor frequency shift for the UCN in a parallel and an antiparallel configuration of magnetic and electric fields. To determine the applied magnetic field (∼1μT) we measure the spin precession frequency of a spin polarized ensemble of 199Hg atoms in the same volume as the UCN by optical means. Currently we reach a precision of 50 fT over 100 s sampling time. I will present ideas how to further improve this magnetometer by using a laser as a light source. (author)