The First Direct Q_EC Measurement in ¹⁶³Ho and the Development of the High-Precision Mass Spectrometer PENTATRAP for Neutrino Physics

An improvement of the upper limit of the electron neutrino mass to a subeV/ C2 level is the goal of the ECHo collaboration. The upper limit of the neutrino mass will be determined with cryogenic microcalorimetry from the analysis of the atomic de-excitation spectrum of 163Dy after the EC in 163Ho. To check for systematic errors an independent measurement of the Q-value of the EC in 163Ho is required. For the first phase of ECHo the issue with the discrepancy between the latest microcalorimetry measurements of the Q-value and its literature value needed to be fixed. For this, a first direct measurement of the Q-value of the EC in 163Ho with the Penning-trap mass spectrometer SHIPTRAP was accomplished in the context of this thesis using the novel PI-ICR technique. Within the uncertainty, it agrees with the latest microcalorimetry measurements. Furthermore, the achieved precision is sufficient for ECHo-1k to be able to improve the upper limit of the electron neutrino mass to 10 eV/c2 (95% C.L.). For further improvements on the neutrino mass, the Q-value needs to be improved, too. For this, the novel high precision Penning-trap mass spectrometer PENTATRAP has been developed and commissioned. PENTATRAP will utilize five Penning traps to test new measurement schemes, which could make it possible to reach un- certainties in the 10-12 regime. Currently, first mass-ratio measurements of the nuclei pair 132Xe and 131Xe with known masses were carried out to test the performance of PENTATRAP