# Measurement of the inhomogeneity of the KATRIN tritium source electric potential by high-resolution spectroscopy of conversion electrons from 83mKr

## TL;DR

The KATRIN experiment measures the electric potential inhomogeneity of its tritium source using high-resolution spectroscopy of conversion electrons from 83mKr to improve neutrino mass determination.

## Contribution

A new method using conversion electrons from 83mKr to measure tritium source potential inhomogeneity in the KATRIN experiment is presented.

## Key findings

- Several-weeks long measurement campaigns were conducted to infer tritium source potential observables.
- The inhomogeneity of the electric potential in the tritium source impacts the neutrino-mass determination.
- Precision spectroscopy of 83mKr conversion electrons quantifies potential distortions in the beta-spectrum.

## Abstract

Precision spectroscopy of the electron spectrum of the tritium \documentclass[12pt]{minimal}
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\begin{document}$$\upbeta $$\end{document}β-decay near the kinematic endpoint is a direct method to determine the effective electron antineutrino mass. The KArlsruhe TRItium Neutrino (KATRIN) experiment aims to determine this quantity with a sensitivity of better than \documentclass[12pt]{minimal}
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\begin{document}$${0.3}{\hbox { eV}}$$\end{document}0.3eV (\documentclass[12pt]{minimal}
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\begin{document}$$90\%$$\end{document}90% C.L.). An inhomogeneous electric potential in the tritium source of KATRIN can lead to distortions of the \documentclass[12pt]{minimal}
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\begin{document}$$\upbeta $$\end{document}β-spectrum, which directly impact the neutrino-mass observable. This effect can be quantified through precision spectroscopy of the conversion-electrons of co-circulated metastable \documentclass[12pt]{minimal}
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\begin{document}$$^{83\text {m}}\text {Kr}$$\end{document}83mKr. Therefore, dedicated, several-weeks long measurement campaigns have been performed within the KATRIN data taking schedule. In this work, we infer the tritium source potential observables from these measurements, and present their implications for the neutrino-mass determination.