Improved search for tensor interactions in nuclear beta decay – bSTILED

This proposal aims at performing the most sensitive search for exotic tensor type interactions contributing to the weak interaction involving the lightest quarks. The observation of such contributions would provide a signature for new physics beyond the standard electroweak model whereas their non-observation will provide the tightest constraints on the couplings associated with those interactions. The search will be performed through high precision measurements of the full beta-energy spectrum in the decay of 6He nuclei. The main instrumental effect which has precluded these measurements to be performed so far, associated with the back-scattering of beta particles on detectors, is eliminated by improving and implementing calorimetric techniques in which the active volume of particle detectors fully enclose the decay source.