Monitoring the energy scale of KATRIN with conversion electrons of a solid ^83mKr source as nuclear standard

For KATRIN to be able to achieve the desired sensitivity of 200 meV/c² for the effective electron neutrino mass, it is of crucial importance that the energy scale of the main spectrometer (18.6 keV) is under control within +/-60 mV at any given time over the planned measurement time of approximately 5 years. Besides conventional high voltage dividers and high precision volt meters, a nuclear standard will be deployed additionally in a separate spectrometer of MAC-E filter type. The filter electrodes of both spectrometers are connected galvanically. For permanent and continuous monitoring an easy to use ion implanted source containing the noble gas ^83mKr was developed and qualified for HV monitoring at the ppm level in the 30 kV regime. This talk presents the methods applied and the achievements made.