Mainz 2026 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 14: Precision Spectroscopy of Atoms and Ions I (joint session A/Q)

Q 14.7: Talk

Monday, March 2, 2026, 18:45–19:00, N 3

Continuation of Laser-Based HV Measurements at COALA — •Hendrik Bodnar, Kristian König, and Wilfried Nörtershäuser — Institute for nuclear physics, TU Darmstadt

The ALIVE experiment at the Collinear Apparatus for Laser spectroscopy and Applied sciences (COALA) at TU Darmstadt aims to measure high voltages in the tens-of-kilovolts range with ppm precision. Conventional techniques rely on voltage dividers that reduce the high-voltage to about 10 V. A drawback of these dividers, however, is the time-dependent drift of their division ratio. In contrast, the ALIVE experiment determines the high-voltage via the Doppler-shift of a transition line in an ion, which has been accelerated using the high-voltage under investigation. Therefore, the ion beam is superimposed with a laser beam and the laser frequency is adjusted to excite the ions. When the rest-frame transition frequency and the laboratory laser frequency are known and measured with sufficient accuracy, respectively, the voltage experienced by the ions can be calculated.

The best precision achieved so far with this approach was 5 ppm [1]. This limitation originated mainly from the design of the acceleration region and its influence on the ion beam. The new design of the accceleration region and first measurements will be presented. Funding from the DFG under project number 461079926 and support under project ID 279384907-SFB 1245 is acknowledged.

[1] Krämer et al., Metrologia 55 268, (2018)

Keywords: Laser; spectroscopy; voltage measurements