Rob Walet, promovendus aan het Nikhef, verdedigt zijn proefschrift maandag 14 november 2022 om 9.45 aan de Vrije Universiteit Amsterdam.
“Advanced instrumentation for gravitational-wave research”
This manuscript presents a laboratory-scale test setup of a laser interferometer that includes suspended optics. The latter, mimicks the fundamental building blocks of a laser interferometer, like those of the kilometerscale gravitational-wave detectors LIGO and Virgo. The test setup has been used to develop and demonstrate novel methods for fast recovery from large misalignments. Here, beam camera images are used for automated pre-alignment of optical cavities, even when they are far outside their linear response region.
An overview of Nikhef’s contribution to the Advanced Virgo Plus filter cavity realization and commissioning is presented. This is part of the detector upgrade in preparation of the O4 observation run. It focuses on the activities by the author on the preparation and installation of the filter cavity mirror suspension systems and the optimization of the local controls.
One of the most demanding elements in the seismic attenuation systems: the maraging steel blade springs, altering the duty cycle of gravitational-wave observatories are investigated in detail. These mechanical components, designed to operate at a high level of stress while maintaining low creep, are subject to sporadic failures that have a large impact on the duty cycle of a gravitational-wave detector. The most common cause of failure is hydrogen embrittlement of the blade material. An overview of recorded blade failure events in gravitational-wave detectors is presented. Results of the study on the hydrogen contamination levels and on the binding energies of the trapping sites inside the material are discussed. Finally, the results of a comparative study, in which the resistance of different materials to stress corrosion cracking was investigated, are presented.
Lastly, this research includes the characterization of a novel instrument to measure gradients of the gravitational field. The concept of the instrument, a ribbon gravity gradiometer is illustrated, followed by a description and the characterization of the individual subsystems. A dedicated gravity-gradient source, a spinning rotor, has been developed to test the instrument and its capabilities to resolve fluctuations in the gravitational field for various rotor spinning frequencies and stand-off distances. The results reveal the potential of the instrument for future application in both third generation gravitational-wave observatories and in geophysical applications.
“Advanced instrumentation for gravitational-wave research” (pdf)
De promotie vindt plaats op maandag 14 november, om 9.45 in de Aula van de Vrije Universiteit, De Boelelaan 1105, 1081 HV Amsterdam.
De promotie zal online te volgen zijn op het YouTube kanaal van de VU.
Meer informatie op de website van de VU.
Promotor: prof. dr. J.F.J. van den Brand
Co-promotor: dr. A. Bertolini en dr. B. Swinkels
Contact: Rob Walet