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Abstract

The BASE (Baryon Antibaryon Symmetry Experiment) experiment, located at CERN’s Antiproton decelerator, tests CPT-invariance by comparing the charge-to-mass ratios and g-factors of protons and antiprotons at high precision. Both measurements rely on the comparison of the particle’s free cyclotron and Larmor frequencies in a high-precision Penning trap. This thesis describes the successful design, implementation and characterization of a superconducting magnetic shimming and shielding system which shields the trapped particle from magnetic field fluctuations induced by the noisy environment of the experiment hall and provides the possibility to tune the magnetic field as well as its first two derivatives. With the help of this system the quadratic inhomogeneity B2 ≈ 100 mT/m² of the magnetic field, which was the dominant uncertainty in the last g-factor measurement was eliminated, which paves the wave for a measurement of the antiproton g-factor at the 100 p.p.t. level. In addition, the shimming system provides the possibility to directly study systematic shifts by introducing magnetic field inhomogeneities on purpose. Finally, the increased homogeneity of the magnetic field creates the novel possibility to use coherent excitation techniques for the measurement of the trapped particle’s Larmor frequency which reduces the power broadening in the g-factor resonance.