Jeffrey Ammon

Nuclear-spin-dependent parity violation (NSD-PV) effects arise from exchange of the Z boson between electrons and the nucleus, and from interaction of electrons with the nuclear anapole moment (a parity-odd magnetic moment induced by electroweak interactions within the nucleus).  These effects cause a mixing of opposite-parity levels in atoms and molecules, where the size of the mixing is inversely proportional to the energy difference of the mixed levels.  We study NSD-PV effects using the rotational levels of diatomic molecules, which can have energy splittings that are about four orders of magnitude smaller than the typical 1 eV atomic energy scale.  We amplify observable signals from NSD-PV by about seven additional orders of magnitude by bringing two rotational levels of opposite parity close to degeneracy with a strong magnetic field.  In this talk, the experimental strategy and expected signal will be discussed, followed by a description of the experimental apparatus.
In particular, two new components of the experiment will be discussed in detail: the “interaction region”, consisting of electrodes and optical delivery components, and our data acquisition system.  We will then discuss our methods for measuring and nullifying nonuniformities in the magnetic and electric fields that we apply, since such nonuniformites can cause systematic errors in our measurements of NSD-PV.  Finally, we will present preliminary results using the test system 138^Ba19^F.  Over the long term, our technique is sufficiently general and sensitive that it should apply to measurements of the NSD-PV couplings for a wide range of nuclei.