Simulating Excited States of Antihydrogen within the Geant4 Simulation of the ASACUSA Experiment

We have performed numerical calculations of decay rates for excited states of hydrogen in magnetic fields. The calculated decay rates were used to implement excited hydrogen states in a Geant4-simulation of an experimental setup intended to measure the hyperfine splitting of antihydrogen. The excited states could thereby decay to lower states in the simulation. Changes in the effective magnetic moment due to the decays were taken into account. The simulation was used to evaluate the efficiency of the experimental setup, depending on which initial antihydrogen state was created. The implementation of excited states also made possible more realistic evaluations of proposed changes in the experimental setup.