Integrated planar antennas for superconducting detector systems for THz beam diagnostics

In this work, superconducting detector systems are developed for use in THz beam diagnostics at particle accelerators operated as scientific light sources. The requirements for such a detector system are determined by the properties of the generated radiation. Due to the underlying physical processes, this is pulse-shaped and reaches repetition rates of several hundred megahertz at modern ring accelerators. This motivates the use of the superconducting detectors made of YBCO and NbN thin films which are used in this work. In contrast to detector types already established in the THz field, these detectors allow not only an averaged analysis but also the resolution of the radiation produced by individual electron bunches over time due to ultra-short response times of less than 100 ps in direct detection. One of the main goals of beam diagnostics is to investigate correlations between the machine parameters of the accelerator and the radiation generated. In particular, the spectrum of the generated radiation is closely related to the spatial distribution of the accelerated particles, although this cannot be measured directly. At ring accelerators, interactions also occur between the spatially distributed electron bunches. These manifest themselves in strong fluctuations in the intensity and spectrum of the radiation generated. Thus, detector systems are needed for diagnostics that have both a comprehensive temporal and spectral resolution capability. The superconducting detector elements investigated in this work are microstructures with dimensions far below the wavelength under investigation, which are operated in conjunction with antennas for radiation coupling. The focus of the work is on the development and investigation of suitable planar antennas as part of the detector circuit, since these significantly determine the spectral behaviour of the detector.