(Crystal Ball experiment, DESY Hamburg, Germany 1981-1982).
The aim of this project was to determine the energy levels of the
so-called Chi-states of the formed b-bbar quark-antiquark system.
Due to the parity of the Chi-states they can only be studied indirectly
by the electromagnetic decay of the Upsilon-prime state.
The Chi energy states are reconstructed by accurate determination of the energies
of the photons produced in these electromagnetic decays.
My main contribution consisted of the development of criteria to suppress the
background signals based on simulation results.