Item

Abstract

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.