For projects like the LEGEND experiment, in which very rare events are
investigated, a detailed analysis of all possible background sources is crucial
to obtain a valuable result. Amongst the potential sources of background in
this experiment are the components of the experimental setup. It is important
to radioassay these components to quantify the potential background they in-
duce and to ensure high levels of radiopurity. The α-chamber at TU Dresden
is a great asset to investigate the alpha-radiation emitted from the surface of
such components.
Before the α-chamber can be used for the purpose of material screening, sev-
eral preparation steps are necessary to make such a material screening pos-
sible. The goal of this work is to go these steps in the preparation. First a
calibration is executed, which enables to match output values of the system
to the energies of detected alpha-particles. After that simulations of the ion-
ization of the used P5 gas with various α-energies are run, with the goal to
find the top position of the ionization cloud and the center of charge. The
purpose of this measure is to determine the energy-dependent parameters of
the position cut and the drift velocity cut, which reduce the background of
the alpha-chamber itself. The last step is the evaluation of the background
spectrum of the chamber. Contaminants are identified and their activity quan-
tified, with the two goals of being able to distinguish these events from sample
events and to reduce the background in the long run.