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HK: Fachverband Physik der Hadronen und Kerne
HK 62: Astroparticle Physics I
HK 62.2: Talk
Thursday, March 23, 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 mν 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 mν2. 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.