Measurement of the Atmospheric $\nu_e$ Spectrum with IceCube

TL;DR

This study measures the atmospheric electron neutrino spectrum from 0.1 to 100 TeV using IceCube data, constraining the flux and kaon contribution, and examining the prompt neutrino flux with implications for cosmic-ray models.

Contribution

First comprehensive measurement of atmospheric $ u_e$ spectrum at high energies with improved event selection and analysis techniques in IceCube.

Findings

Conventional $ u_e$ flux is about 1.3 times the baseline prediction.

Kaon contribution to neutrino flux is approximately 1.3 times the baseline.

Prompt neutrino flux is consistent with zero within uncertainties.

Abstract

We present a measurement of the atmospheric $\nu_e$ spectrum at energies between 0.1 TeV and 100 TeV using data from the first year of the complete IceCube detector. Atmospheric $\nu_e$ originate mainly from the decays of kaons produced in cosmic-ray air showers. This analysis selects 1078 fully contained events in 332 days of livetime, then identifies those consistent with particle showers. A likelihood analysis with improved event selection extends our previous measurement of the conventional $\nu_e$ fluxes to higher energies. The data constrain the conventional $\nu_e$ flux to be $1.3^{+0.4}_{-0.3}$ times a baseline prediction from a Honda's calculation, including the knee of the cosmic-ray spectrum. A fit to the kaon contribution ($\xi$) to the neutrino flux finds a kaon component that is $\xi =1.3^{+0.5}_{-0.4}$ times the baseline value. The fitted/measured prompt neutrino flux from charmed hadron decays strongly depends on the assumed astrophysical flux and shape. If the astrophysical component follows a power law, the result for the prompt flux is $0.0^{+3.0}_{-0.0}$ times a calculated flux based on the work by Enberg, Reno and Sarcevic.