Fundamental weak interaction studies using polarised nuclei and ion traps

Two experiments to search for new physics beyond the standard model for ele ctroweak interactions by measuring correlations between different spin and momentum vectors in nuclear beta -decay are discussed. In the first experim ent the correlation between the emission asymmetry and the longitudinal pol arisation of positrons emitted by polarised nuclei is determined. This type of measurement is sensitive to the presence of right-handed currents but a lso to possible scalar and tensor-type currents in the weak interaction. Th e aim of the second experiment is to determine the beta nu -correlation in beta -decay by measuring the energy spectrum of the recoil ions, using a Pe nning trap and a retardation spectrometer. In this case the focus is on the search for scalar currents in the weak interaction. The results of the exp eriments presented here are complementary to results from experiments in mu on decay and at high-energy colliders.