First Evidence For Atmospheric Neutrino-Induced Cascades with the IceCube Detector - Astrophysics > High Energy Astrophysical PhenomenaReportar como inadecuado




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Abstract: IceCube is an all-flavor, cubic kilometer neutrino telescope currently underconstruction in the deep glacial ice at the South Pole. Its embedded opticalsensors detect Cherenkov light from charged particles produced in neutrinointeractions in the ice. For several years IceCube has been detecting muontracks from charged-current muon neutrino interactions. However, IceCube hasyet to observe the electromagnetic or hadronic particle showers or -cascades-initiated by charged-current or neutral-current neutrino interactions. Thefirst detection of such an event signature is expected to come from the knownflux of atmospheric electron and muon neutrinos.A search for atmospheric neutrino-induced cascades was performed using 275.46days of data from IceCube-s 22-string configuration. Reconstruction andbackground rejection techniques were developed to reach, for the first time, asignal-to-background ratio ~1. Above a reconstructed energy of 5 TeV, 12candidate events were observed in the full dataset. The signal expectation fromthe canonical Bartol atmospheric neutrino flux model is 5.63+-2.25 events,while the expectation from the atmospheric neutrino flux as measured byIceCube-s predecessor array AMANDA is 7.48 +- 1.50 events. Quoted errorsinclude the uncertainty on the flux only.While a conclusive detection can not yet be claimed because of a lack ofbackground Monte Carlo statistics, the evidence that we are at the level ofbackground suppression needed to see atmospheric neutrino-induced cascades isstrong. In addition, one extremely interesting candidate event of energy 133TeV survives all cuts and shows an intriguing double pulse structure in itswaveforms that may signal the -double bang- of a tau neutrino interaction.



Autor: Michelangelo D'Agostino

Fuente: https://arxiv.org/



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