First detection and energy measurement of recoil ions following beta decay in a Penning trap with the WITCH experiment

The WITCH experiment (Weak Interaction Trap for CHarged particles) will search for exotic interactions by investigating the \( \beta\) -\( \nu\) angular correlation via the measurement of the recoil energy spectrum after \( \beta\) -decay. As a first step the recoil ions from the \( \beta^{-}_{}\) -decay of 124In stored in a Penning trap have been detected. The evidence for the detection of recoil ions is shown and the properties of the ion cloud that forms the radioactive source for the experiment in the Penning trap are presented.