WITCH: Testing the standard model using a β-recoil spectrometer with a trapped ion cloud as source Original Research Article

The combination of a zero thickness source of β radioactivity, consisting of an ion-cloud in a Penning trap, with a retardation spectrometer has for the first time allowed the construction of a set-up that can measure the β recoil spectrum of any nucleus. This opens a number of severely hampered areas of study, such as lepton angular correlations and charge state distributions after β-decay. The former allows extraction of Standard Model violating S and T contributions to the weak interaction. An overview of the set-up is given in this presentation.