High-voltage monitoring with a solenoid retarding spectrometer at the KATRIN experiment

The KATRIN experiment will measure the absolute mass scale of neutrinos with a sensitivity of m(v) = 200 meV/c(2) by means of an electrostatic spectrometer set close to the tritium beta-decay endpoint at 18.6 keV. Fluctuations of the energy scale must be under control within +/- 60 mV (+/- 3 ppm). Since a precise voltage measurement in the range of tens of kV is on the edge of current technology, a nuclear standard will be deployed additionally. Parallel to the main spectrometer the same retarding potential will be applied to the monitor spectrometer to measure 17.8-keV K-conversion electrons of Kr-83m. This article describes the setup of the monitor spectrometer and presents its first measurement results.