Abstract (eng)
In the non-perturbative, low-energetic regime of QCD, the interaction between antikaons and nucleons close to threshold still poses many unresolved questions and is thus the subject of extensive research. The study of the antikaon-N interaction allows to gain insight in the complex processes of chiral symmetry breaking, leading to a better understanding of fundamental concepts in hadron physics like the origin of the hadron masses. X-ray spectroscopy of kaonic atoms provides a versatile tool to study the strong interaction at low relative energies via a direct observation of its influence on the ground state of kaonic atoms. The SIDDHARTA-2 experiment, currently under construction at the DAΦNE collider complex in Frascati, Italy, aims to
determine the energy shift and width of the kaonic deuterium 1s state induced by the strong interaction with precisions of 30 eV and 75 eV, respectively.
However, this measurement is severely aggravated by the low kaonic deuterium X-ray yield. Due to this challenge, an improvement of the signal-to-background ratio by at least one order of magnitude compared to the previously performed kaonic hydrogen measurement (SIDDHARTA) is crucial. This increase will be achieved in SIDDHARTA-2 through the implementation of three updates: a lightweight, cryogenic target, a newly developed large-area X-ray detection system consisting of Silicon Drift Detectors, and a dedicated veto system for background suppression. The veto system consists of an outer veto system (Veto-1) for active shielding and an inner veto system (Veto-2)
for active shielding as well as the suppression of signal-correlated background in the form of charged particles. Excellent timing properties are required for both veto detectors.
The Veto-2 system was constructed, tested and optimised at the Stefan Meyer Institute. The time resolution, detection effciency and its performance within a broad temperature range were studied and satisfying results were obtained. The first detector units of the Veto-2 system were installed in the SIDDHARTA-2 setup in Frascati.