Development of Single Sideband Down Converters for Precise Measurements of the Axial Frequency of a Single Trapped Antiproton

The Baryon Antibaryon Symmetry Experiment (BASE) at the antiproton decelerator of CERN, Geneva, Switzerland aims at precise comparisons of the fundamental properties of the antiproton and proton. Such comparisons are interesting because any measured asymmetry between a matter and antimatter-conjugates would hint at physics beyond the Standard Model. In this bachelor's project, a single sideband (SSB) down converter for the measurement of the axial frequency of an antiproton or a proton was developed. The goal is to down-convert the axial frequency into the frequency range of the FFT analyzer and to increase the down-mixed signal to noise ratio of the detection system. In addition, an active feedback cooling system was developed by using this SSB down converter. The temperature of the axial detection system is about 8 Kelvin without feedback. It is demonstrated that the feedback system is capable to decrease the temperature of the detection system and thus that of the particle by about a factor of 3 to 5. This leads to reduction of resonance line widths, faster particle preparation cycles and thus improves measurement precision.