Measurements of beta-energy spectra in nuclear beta decay with a calorimetric technique

Searches for exotic tensor interactions in beta decay have motivated new measurements of beta-energy spectra in allowed Gamow-Teller transitions. Such measurements enable the most direct access to the Fierz interference term which constitutes a very sensitive probe to the presence of exotic couplings. We have implemented a calorimetric technique which makes use of high energy beams produced at the National Superconducting Cyclotron Laboratory. The technique eliminates the major instrumental effect related to the back-scattering of beta particles in surrounding matter and detectors but poses other specific challenges. We have performed measurements in the decays of $^6$He and $^{20}$F. In this contribution we describe the status of the data analysis with emphasis on the discussion of specific systematic effects.