Tackling the mystery of cosmic rays by searching for cosmogenic neutrinos - transforming the ARIANNA pilot program into a discovery instrument
Astrophysics and Astronomy
Final Report Abstract
The detection of ultra-high-energy (UHE) neutrinos is a key to solve the 100-year-old mystery of the origin of cosmic rays and one of the crucial milestones for astroparticle physics. Their detection gives access to the most violent phenomena in the universe, those that happen in the vicinity of super-massive black holes (active galactic nuclei), in neutron star mergers or gamma ray bursts. The only cost-efficient way to measure these UHE neutrinos is via a sparse array of radio antenna stations installed, for instance, in the Antarctic or Arctic ice: A neutrino interaction in the ice generates a few-nanoseconds long radio flash that can be detected from kilometerlong distances. The ARIANNA testbed detector is an array of radio detector stations that are installed on the Ross Ich Shelf in Antarctica with the purpose to search for these UHE neutrinos and to measure their properties. Because of the limited size of the testbed detector and because of the tiny flux, no UHE neutrino has been observed yet with ARIANNA but this pilot program serves as an important technology pathfinder to demonstrate the technology is ready to construct a much larger array of radio detector stations with enough sensitivity to measure the low flux of UHE neutrinos. In this project I made important contributions to demonstrate the readiness of the radio detection technique. In the beginning of the project, I devoted most time on developing a novel simulation code (NuRadioMC) to precisely simulate the signals we expect from UHE neutrinos; and developing a modular reconstruction framework for radio detector data (NuRadioReco). I made both projects open-source from the beginning. Both codes are widely used by now and became the standard tool in my field of research. NuRadioMC also models the underlying physics processes with an unprecedented level of detail which enables a wealth of opportunities to study different physics phenomena such as flavor physics. Furthermore, the flexibility of NuRadioMC enabled design studies and optimizations of future detectors. These tools then enabled me to study how and how well the direction and energy of UHE neutrinos can be reconstructed which are the main parameters of interest. It is a complex task to extract the neutrino properties from the recorded short radio flashes and requires the reconstruction of several independent low-level parameters. I developed new reconstruction techniques that were first evaluated against simulated data but as much as possible tested in insitu measurements. For example, I developed a novel technique to measure the distance to the neutrino interaction in the ice, which is an important quantity to determine the neutrino energy. I verified the method in a measurement campaign on the Ross Ice Shelf. An interesting side product of this test was a continuous measurement of the snow accumulation with millimeter precision with potential relevance for Glaciology and climate science as a future UHE neutrino detector will cover large patches of Antarctic ice. The work performed in this project made important contributions to demonstrate the capabilities and readiness of the radio technique to detect UHE neutrinos which is most visible by the fact that a radio component is included in the vision for the next generation of neutrino observatory (IceCube-Gen2). This detector will have enough sensitivity to measure cosmogenic neutrinos and to finally tackle them mystery of cosmic rays.
Publications
- “Neutrino vertex reconstruction with in-ice radio detectors using surface reflections and implications for the neutrino energy resolution” J. Cosmol. Astropart. Phys 11(2019)030
ARIANNA collaboration (…, C. Glaser et al.)
(See online at https://doi.org/10.1088/1475-7516/2019/11/030) - “NuRadioReco: A reconstruction framework for radio neutrino detectors”, European Physics Journal C 79: 464 (2019)
C. Glaser et al.
(See online at https://doi.org/10.1140/epjc/s10052-019-6971-5) - “Targeting cosmogenic neutrinos with the ARIANNA experiment”, Advances of Space Research 64 (2019) 2595- 2609
ARIANNA collaboration (…, C. Glaser et al.)
(See online at https://doi.org/10.1016/j.asr.2019.06.016) - “NuRadioMC: Simulating the radio emission of neutrinos from interaction to detector”, European Physics Journal C 80, 77 (2020)
C. Glaser et al.
(See online at https://doi.org/10.1140/epjc/s10052-020-7612-8) - “The signatures of secondary leptons in radio-neutrino detectors in ice”, Phys. Rev. D 102, 083011
D. García-Fernández, C. Glaser and A. Nelles
(See online at https://doi.org/10.1103/PhysRevD.102.083011) - ”Probing the angular and polarization reconstruction of the ARIANNA detector at the South Pole”, Journal of Instrumentation 15 (2020) P09039
ARIANNA collaboration (…, C. Glaser et al.)
(See online at https://doi.org/10.1088/1748-0221/15/09/P09039)
