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This article reviews space-based detection methods for cosmic neutrinos using celestial bodies like Earth, the Moon, and the Sun as targets. When ultra-high-energy neutrinos interact with these bodies, they generate particle cascades that produce detectable optical and radio signals from orbiting or balloon-borne instruments. Current detection thresholds are above 1 PeV for optical Cherenkov methods and 100 PeV for radio detection, with different techniques offering varying sensitivities to neutrino flavors and operational duty cycles.
Why it matters
Space-based neutrino detection enables observation of the highest-energy neutrinos in the universe, which cannot be efficiently detected by ground-based observatories alone. These measurements could reveal sources of ultra-high-energy cosmic rays and provide insights into extreme astrophysical phenomena like active galactic nuclei and gamma-ray bursts.
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⚠️ Preprint – Noch nicht peer-reviewed
Dieser Artikel wurde noch nicht von unabhängigen Experten begutachtet. Die Ergebnisse sind vorläufig und sollten mit Vorsicht interpretiert werden.
Abstract: Space-based neutrino detection employs celestial bodies, the Earth, moon, and the sun, as neutrino targets and particle cascade generators. These cascades, or showers, have an immense content of charged particles, mainly electrons and positrons, that can form signals that can be detected by orbiting or balloon-borne (for the Earth) experiments. Here the focus will be on the using the Earth as the neutrino target and using the atmosphere to generate optical and radio signals from extensive air showers (EAS). Cascades in the Earth itself can also generate Askaryan radiation in ice, where the radio transparency allows the signal from in ice neutrino-induced showers to eventually refract out of the Earth’s surface. These different techniques also have different neutrino-flavor detection sensitivities and duty cycles, i.e. experimental live time fractions. For example, optical measurements need to be performed close to astronomical night and are also affected by the level of moonlight and distribution of clouds in the the viewing direction of the EAS. The radio technique can be operate with nearly 100% efficiency, as long as sources of anthropogenic and other backgrounds are minimal. Given the distances for viewing the neutrino-induced signals from sub-orbital or low Earth orbit (LEO) altitudes, the neutrino energy thresholds for detection are currently above $sim$ 1 PeV for optical Cherenkov detection and 100 PeV for radio detection. In this chapter, the nature of the cosmic neutrino interactions, shower development, and optical and radio signal generation and detection will be detailed. This will be done by discussing experiments that have used such signals to set limits on the very-high and ultra-high energy cosmic neutrino flux. We will also discuss the design and simulated performance of the next generation of space-based cosmic neutrino detection experiments.