Rydberg Excitation of Hydrogen for studies towards Antihydrogen Deexcitation

The CERN Antiproton Decelerator (AD) facility hosts antimatter experiments, which produce antihydrogen in a wide range of Rydberg states. Precision measurements require groundstate antiatoms that are currently only available through spontaneous decay. The antihydrogen experiments can be categorised as trap and beam experiments. The trap experiments use a magnetic field to accumulate atoms and let them decay before performing measurements, but the beam experiments like AE$\bar g$IS and ASACUSA cannot afford to wait for the antiatoms to spontaneously decay. The group I joined for my bachelor thesis is investigating methods to deexcite highly excited antiatoms within a few tens of $\unit{\mu s}$. Several deexcitation schemes have been proposed. However, before they are employed on antihydrogen, a proof-of-principle experiment on hydrogen has been developed. It aims to produce Hydrogen atoms in highly excited states before demonstrating its deexcitation. In this work, I was involved in both experimental and theoretical aspects. On the experimental side, I helped set up the beamline and the Doppler-spectroscopy diode and Ti:Sa excitation laser, wrote a data-acquisition program, took spectroscopic data of the hydrogen source, and analysed them. The spectroscopy data helped the characterisation of the plasma. On the theoretical side, I used a code to find the optimal E and B fields and their mutual orientations to produce circular states via the cross-field methods. The results will guide the experimental implementation of the method.