Cosmic Rays and the Radio Neutrino Observatory Greenland (RNO-G)

• Main Author: Pyras, Lilly
• Other Authors: Nelles, Anna
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) 2024
• Subjects: Cosmic rays; Neutrinos; RNO-G; Radio detection; atmospheric muons; Greenland; greenlandic
• Online Access: https://bib-pubdb1.desy.de/record/612609; https://bib-pubdb1.desy.de/search?p=id:%22PUBDB-2024-05403%22

Neutrinos are unique messengers, as they travel unimpeded over cosmological distances, pointing back to their sources. As their production is tightly coupled to that of ultra-high energy cosmic rays, they could help us to understand the ultra-high energy universe. However, the expected neutrino flux at the highest energies is very low, and the detection of neutrinos is difficult due to their small cross section. Therefore, measuring the neutrino flux requires large detection volumes of dense media. One such effort is the Ra- dio Neutrino Observatory Greenland (RNO-G), which targets the detection of neutrinos above PeV energies in the Greenlandic ice shield. When a neutrino interacts with a nucleus in the ice, it induces particle cascades that produce radio emission via the Askaryan effect. The attenuation length of glacial ice is ????(1 km) at radio frequencies which allows for large, and sparsely instrumented detection volumes. The hybrid design, consisting of antennas deep in the ice and shallow antennas just below the surface, also provides sensitivity to cosmic ray air showers, which improves background rejection for in-ice neutrino events. The focus of this work is the precise estimation of air showers in RNO-G and the identification of atmospheric muons originating from air showers. For this purpose, the surface signal chain of the shallow detector component and its diode trigger are characterized. The digitizer board and trigger are tested for functionality and performance prior to deployment. These studies are essential for understanding the measured signals and making robust event rate predictions. To obtain the number of detected cosmic rays, a detailed Monte Carlo study is performed, which suggests that 3 to 10 air showers per day and seven RNO-G stations are expected to be measured. The energy threshold is around 1e17 eV and depends strongly on the trigger threshold. The performance in air shower detection has a direct impact on the identification of neutrinos, since ultra-high energy muons from air ...