Wideband precision stabilization of the -18.6 kV retarding voltage for the KATRIN spectrometer

Understand

The Karlsruhe Tritium Neutrino Experiment (KATRIN) measures the effective electron anti-neutrino mass with an unprecedented design sensitivity of 0.2 eV (90 % C.L.).

• In this experiment, the energy spectrum of beta electrons near the tritium decay endpoint is analyzed with a highly accurate spectrometer.
• To reach the KATRIN sensitivity target, the retarding voltage of this spectrometer must be stable to the ppm level and well known on various time scales ($\mu s$ up to months), for values around -18.6 kV.
• A custom-designed high-voltage regulation system mitigates the impact of interference sources in the absence of a closed electric shield around the large spectrometer vessel.