The WITCH experiment: completion of a set-up to investigate the   structure of weak interactions with a Penning trap
  The WITCH experiment aims to study a possible admixture of a scalar or tensor type interaction in beta decay by determining the beta-neutrino angular correlation from the shape of the recoil energy spectrum. The installation period was completed and intensive commissioning of the set-up was performed already. The lay-out of the WITCH set-up and results of commissioning tests performed until now are described here, showing that the full set-up up to the spectrometer is now operational, although several efficiencies are still to be improved. Due to its feature of being able to measure the energy spectrum for recoil ions, the WITCH experiment also opens possibilities for other observables. 
V.Yu. Kozlov, N. Severijns, D. Beck, M. Beck, S. Coeck, B. Delaure, S.   Kopecky, A. Lindroth, P. Delahaye, F. Wenander, V.V...