J. Deutsch

A novel approach for measuring the beta-neutrino angular correlation in nuclear beta decay

The experiment described here will search for deviations from the V-A structure of the standard electroweak model. It is based on measuring the recoil energy spectrum in nuclear beta decay which is determined by the electron-neutrino angular correlation. For pure Fermi decays this is exactly known in the standard model and any deviation will point to additional scalar interaction. The experiment consists of a Penning trap coupled to a retardation spectrometer to measure the energy of the recoiling daughter nuclei. The current status will be presented.

Search for physics beyond the standard model via a polarization-asymmetry correlation experiment on 107In

We report on a new precision measurement of the longitudinal polarization of positrons emitted by polarized 107In nuclei. Preliminary results yield a lower limit of 303 GeV/c2 for the mass of a possible, predominantly right-handed, W gauge boson, if interpreted in the framework of the manifest, left-right symmetric model. In more general left-right symmetric models our result is complementary to those from muon decay experiments and to results from searches for a similar particle in collider experiments. Our data also provide new results on possible tensor contributions to the weak interaction.