Beta-decay experiments revealed the vector and axial-vector nature of the weak interaction over 50 years ago. A half century later, experimental limits on exotic chirality-flipping scalar and tensor interactions remain rather weak. In the case of tensor currents, limits on the couplings are of order 1-10% relative to axial-vector couplings. Angular correlations between the nuclear recoil and beta particle provide a robust probe of exotic couplings. Several angular correlation experiments are underway, utilizing modern trapping and radiation detection techniques in order to overcome the systematic uncertainties that have plagued past experiments. We will discuss recent results from angular correlation studies with 8Li and 6He, as well as new techniques being investigated to overcome current experimental limitations. A promising possibility is the use of Cyclotron Radiation Emission Spectroscopy (CRES) to determine the Fierz interference term via precision beta spectrum measurements. The technique, recently demonstrated by the Project 8 collaboration, has shown promising results with mono-energetic conversion-electron spectra. Thoughts on the use of CRES in precision weak interaction studies will be presented.
Argonne Physics Division Seminar Schedule