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Abstract

The Penning-trap mass spectrometer PENTATRAP aims for measurements of mass ratios of single stable and long-lived highly-charged ions with a relative uncertainty on the order of 10⁻¹¹. For the mass-ratio measurement the cyclotron frequencies are measured for two ion species inside the magnetic field of the Penning traps. The ions’ eigenfrequencies are measured by means of a non-destructive detection of image currents. Essential part of each detection circuit is a cryogenic high-quality (high-Q) resonator, realised as a superconducting NbTi or copper coil in a copper housing. PENTATRAP incorporates detectors for the axial and the modified cyclotron mode, which enable direct cooling and detection of these modes. The tiny image currents induced by a single ion become detectable with the help of cryogenic GaAs FET amplifiers. Due to a modification of the PENTATRAP setup, a new detection system is needed. This detection system was developed in the framework of this thesis. The new detection system features identical housings for the axial and the cyclotron resonators. Both coil types were designed as toroidal coils. The previous amplifier circuit was adapted to the new amplifier box. First tests of the resonators, with and without the cryogenic amplifier, were conducted inside a cryocooler. For a ³⁵Cl¹⁰⁺-ion the final resonators will lead to a dip width of ~1.73 Hz for a dip detection measurement with the axial resonator at the correction electrode. With the cyclotron resonator connected to one half of the correction electrode the expected cooling time constant for this ion is ~36.6 s.