Energy Reconstruction for Radio Neutrino Detectors

• Main Author: Welling, Christoph
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: 2022
• Subjects: ddc:539; Greenland
• Online Access: https://opus4.kobv.de/opus4-fau/frontdoor/index/index/docId/20115; https://nbn-resolving.org/urn:nbn:de:bvb:29-opus4-201153; https://opus4.kobv.de/opus4-fau/files/20115/PhD_Thesis.pdf

Currently, the technique to detect neutrinos at the EeV energy scale by the radio signals emitted when they interact in glacial ice, is making the transition from small prototype experiments to full discovery-scale detectors. In the summer of 2021, con- struction started for the Radio Neutrino Observatory Greenland (RNO-G), the first detector large enough to be sensitive to the expected flux of cosmogenic neutrinos. With the prospect of the first detection of a neutrino using the radio technique, the ability to reconstruct their properties from the radio signal becomes more and more important. The goal of this thesis is to develop methods that would allow for the reconstruction of the energy of a neutrino detected by RNO-G or a similar detector. At the same time, radio detection is a well-established technique for cosmic ray observatories. The radio emission from air showers is due to very similar effects, and shares many properties with the radio signals expected from high-energy neutrinos. Thus, air showers can be a useful test case when trying to develop reconstruction techniques for radio neutrino detectors. To reconstruct the energy of an air shower, radio cosmic ray observatories usually use the amplitude of the radio signal measured at a number of different locations. Such an approach is not feasible for a radio neutrino detector, because most events are expected to only be detected by a single radio station. Therefore, the first task was to develop a way to reconstruct the energy of an air shower using only a single detector station. This was accomplished by first using a technique called forward folding, which fits an analytic model to the measured waveforms, to determine the radio signal’s frequency spectrum. By using the shape of this spectrum as a proxy for the angle under which the radio signal is recorded, called the viewing angle, the shower energy can be reconstructed with a resolution of around 15%. The forward folding technique used to reconstruct the radio signal from an air shower relies on ...