Karlsruhe 2024 – scientific programme

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T: Fachverband Teilchenphysik

T 42: Neutrino astronomy 2

T 42.3: Talk

Tuesday, March 5, 2024, 16:30–16:45, Geb. 30.23: 6/1

Energy-dependent measurement of seasonal variations in the atmospheric muon neutrino spectrum — •Karolin Hymon, Tim Ruhe, and Lucas Witthaus for the IceCube collaboration — Astroparticle Physics WG Rhode, TU Dortmund University, Germany

A large number of atmospheric neutrinos are detected in ground-based neutrino telescopes, such as the IceCube Neutrino Observatory. These neutrinos are generated in extensive air showers initiated by a cosmic rays interacting with air nuclei in the atmosphere. Conventional atmospheric neutrinos originate mostly from kaons and pions that decay into neutrinos. The production of atmospheric neutrinos varies seasonally due to temperature variations in the atmosphere during the year. As the temperature increases, the atmosphere expands and the atmospheric density decreases. The seasonal variation increases with energy, as parent particles interact at higher altitudes in the atmosphere and the interaction cross section increases with energy. Consequently, the probability of decay for the parent mesons increases, leading to a subsequent increase in the neutrino flux. This talk presents the measurement of seasonal variations in the muon neutrino energy spectrum between 125 GeV and 10 TeV. The determination of the neutrino energy presents an ill-conditioned inverse problem, requiring to infer the energy from measured detector quantities. This challenge is addressed by the Dortmund Spectrum Estimation Algorithm (DSEA+), which uses machine learning methods to unfold the neutrino energy using 11.5 years of IceCube data.

Supported by BMBF (ErUM) and DFG (SFB 1491)

Keywords: atmospheric neutrinos; extensive air showers; seasonal variations; IceCube; unfolding