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Abstract

Imaging atmospheric Cherenkov telescopes are used for the detection of highest-energy
γ-rays.
This thesis focuses on two experiments equipped with such telescopes: The operating High
Energy Stereoscopic System (H.E.S.S.) and the future Cherenkov Telescope Array (CTA).
Four of the five H.E.S.S. cameras saw a major electronics upgrade a few years ago enabling
improved readout and analysis techniques mainly at the highest energies. The Compact
High-Energy Camera (CHEC) is a design for the Small-Sized Telescopes of CTA focusing on
the detection of γ-rays with energies exceeding 1 TeV.
The first part of the thesis is dedicated to the characterisation of two CHEC prototype
cameras developed successively: CHEC-M and CHEC-S. I present results of laboratory and
on-telescope measurements for both cameras. In the case of CHEC-S, I focus on those
parameters that had been shown to be performance-limiting in CHEC-M and which were
therefore addressed in the design iteration for CHEC-S.
The second part is devoted to the upgraded H.E.S.S. cameras. I present results of Monte-
Carlo simulation studies, analysis developments, and performance measurements using fullwaveform
readout. In the former case I demonstrate a general consistency between simulations
and measurements, in the latter case I show that the use of full-sampled waveform
readout improves the performance, especially at the highest energies.
In the last part, I present a new analysis of the Galactic γ-rays source HESS J1646–458
which is associated with Westerlund 1, the most massive stellar cluster in our Galaxy.