Laser-Based High-Voltage Measurements with 1 ppm Accuracy

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We aim to measure high voltages in the range of 10 kV to 100 kV with a relative accuracy of at least 1E-6 (1 ppm). To achieve this, ions of a specific velocity class inside an ion beam are prepared in a particular atomic state and then accelerated with this high voltage. The Doppler shift prior to and after the acceleration is determined and its change corresponds to the change of the ions velocity while passing through the applied potential difference. With this approach we can trace back the high voltage measurement to an optical transition in an ion (Ca+/In+). This traceability is of great interest for metrology institutes but also for high-precision experiments in physics that require extremely accurate high voltage measurements. Examples are the KATRIN experiment for the measurement of the electron-antineutrino mass in Karlsruhe or precision experiments on electron-cooled ions at storage rings. The proposed project is based on earlier and published studies of the applicant, which already demonstrated a significant improvement compared to previous studies performed by other groups with this technique. A detailed analysis of the remaining systematic uncertainties resulted in a list of technological improvements of the ion beam line to remove or reduce their influence. Moreover, a new measurement scheme will be implemented and tested, employing a Raman transition to populate the excited metastable 3d state in the Ca+ ion and a fast scanning procedure utilizing EOM sidebands. This will allow us to further improve the measurement accuracy.During the three-year project the proposed amendments will be implemented in the framework of a doctoral study and their implications for the laser-based high-voltage measurements will be studied.