The KATRIN forward beam monitor detector

The KATRIN detector aims to measure the neutrino mass with a sensitivity level of 200 meV. This will be done by measuring the β-electron spectrum from the decay of tritium. The source properties need to be stable and known to a high precision in order to extract the neutrino mass. For this reason the source will undergo extensive measurements from several monitoring systems. The Forward Beam Monitor Detector (FBMD) is one such monitoring system. This detector is being constructed at the University of Wuppertal and will be transported on-site to the KATRIN detector within the next few months. The working principle and the performance of the FBMD are presented, including a comparison between vacuum simulations and vacuum measurements, software details of the slow control systems, and the resulting spectra of low-energetic electrons.