Ion monitoring within the KATRIN experiment

The KATRIN (KArlsruhe TRItium Neutrino) experiment aims to measure the effective neutrino mass with an unprecedented design sensitivity of 0.2 eV at the 90% confidence level by measuring the energy of the electron that is produced in tritium beta decay. Magnetic fields guide charged particles through the energy-analyzing retarding spectrometers towards the detector. In this process, ions produced from the decay act as a background source as they further ionize residual gas and produce secondary electrons. Ion-blocking mechanisms are implemented in the source and transport section for which we found preferred settings and neutralization times. We monitor the small ion flux in the spectrometers by the current that they make by striking electrodes along the beamline and by electron generation by ion-impact in the spectrometer. We will present results from commissioning tests as well as the performance during our first neutrino mass measurement campaigns.