Instrument Development for the Next-Generation Astroparticle Detectors: Einstein Telescope and CTAO

The Einstein Telescope and the Cherenkov Telescope Array Observatory (CTAO) are two next-generation instruments currently in the design and construction phase to advance the field of astroparticle physics. Although they explore different aspects of it, gravitational waves and gamma rays, both face similar instrumentation challenges. In this thesis, specialised high-speed cameras are developed for each experiment, which are related by their shared utilisation of high-speed amplification and digitisation. In the first part of this thesis, a monitoring tool for the Einstein Telescope is developed: A 56-pixel proof-of-concept phase camera capable of simultaneously measuring the spatial phase and amplitude of different radio-frequency components of a laser. Such a phase camera allows the determination of the mode content and wavefront aberrations caused by misalignment in the interferometer. A key innovation of the prototype is the introduction of a multimode fibre array, which significantly improves image quality by stabilising the phase relation between the pixels at higher frame rates. High-gain, high-bandwidth, low-noise amplification is developed to enable the digital demodulation to acquire the phase and amplitude information of the different radio frequency components. The complete signal chain is designed, built, and characterised with an in-depth study of the acquisition of phase and amplitude noise. To scale up the camera, the CTC digitising ASIC from the SST Camera is adapted and integrated into the system. Finally, a commissioning study of the phase camera at the ET Pathfinder is conducted to verify the performance and ability to observe and characterise the mode content. In the second part, the front-end electronics for the SST, an Imaging Air Cherenkov Telescope (IACT) of CTAO, are characterised and optimised, with particular focus on the TARGET ASIC pair CTC and CT5TEA, the heart of the SST Camera. Throughout this thesis, a standardised calibration chain is developed for largescale production of the camera, focusing on the digitisation ASIC CTC, refining established routines and introducing new ones. Special emphasis is placed on its temperature-stable performance, with in-situ recalibration techniques in the camera for temperature-sensitive calibration steps. Additionally, comprehensive evaluation and tuning of the Wilkinson ADC in the CTC are conducted to ensure meeting the specific performance criteria. The validation and verification results demonstrate that the CTC is suitable for IACTs and meets the CTAO’s performance requirements.