SMuK 2023 – wissenschaftliches Programm

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HK: Fachverband Physik der Hadronen und Kerne

HK 62: Astroparticle Physics I

HK 62.2: Vortrag

Donnerstag, 23. März 2023, 14:30–14:45, SCH/A252

Measurement of the nuclear transition energies of ^83mKr using the condensed krypton source of KATRIN — •Matthias Böttcher and Benedikt Bieringer for the KATRIN collaboration — Institut für Kernphysik, WWU Münster

The KATRIN experiment aims to measure or exclude the effective electron neutrino mass m_ν down to 0.2 eV/c² (90 % C.L.) by measuring the tritium beta spectrum near its endpoint E₀, and performing a fit including the parameters E₀ and m_ν². Since these are highly correlated, a systematic shift influencing the obtained neutrino mass would be visible in the endpoint and thus the tritium Q value. The KATRIN Q value can be determined by absolute calibration with ^83mKr conversion electron lines. This is however limited by the nuclear gamma transition energy uncertainties of ^83mKr to 0.5−0.6 eV accuracy. The excited nucleus of ^83mKr decays in a two-step cascade of 32.2 eV and 9.4 eV highly converted gamma transitions. In a new four weeks measurement campaign performed at KATRIN, a large set of conversion electron lines including a new line was measured extensively with a condensed krypton source. Following the method described in ref. EPJ C 82 (2022) 700, the ^83mKr nuclear transition energies can be determined, which can allow for a reduction of the Q value uncertainty to below 100 meV. In this talk the principle, measurements, and analyses for improving the ^83mKr transition energy uncertainties are presented. This work is supported by BMBF under contract number 05A20PMA.