Measurement of Atmospheric Neutrino Oscillations with IceCube

TL;DR

This paper reports the first significant detection of atmospheric neutrino oscillations at energies above 20 GeV using IceCube data, confirming oscillation parameters with high confidence.

Contribution

It provides the first statistically significant measurement of high-energy atmospheric neutrino oscillations using IceCube's DeepCore detector, extending oscillation studies to higher energies.

Findings

Disappearance of low-energy upward-going muon neutrinos observed.

Oscillation parameters measured: Δm²₃₂ ≈ 2.3×10⁻³ eV², sin²(2θ₂₃) > 0.93.

Non-oscillation hypothesis rejected with >5σ significance.

Abstract

We present the first statistically significant detection of neutrino oscillations in the high-energy regime ($>$ 20 GeV) from an analysis of IceCube Neutrino Observatory data collected in 2010-2011. This measurement is made possible by the low energy threshold of the DeepCore detector ($\sim 20$ GeV) and benefits from the use of the IceCube detector as a veto against cosmic ray-induced muon background. The oscillation signal was detected within a low-energy muon neutrino sample (20 -- 100 GeV) extracted from data collected by DeepCore. A high-energy muon neutrino sample (100 GeV -- 10 TeV) was extracted from IceCube data to constrain systematic uncertainties. Disappearance of low-energy upward-going muon neutrinos was observed, and the non-oscillation hypothesis is rejected with more than $5\sigma$ significance. In a two-neutrino flavor formalism, our data are best described by the atmospheric neutrino oscillation parameters $\Delta m^2_{23}= (2.3^{+0.6}_{-0.5})\cdot 10^{-3}$ eV$^2$ and $\sin^2(2 \theta_{23})>0.93$, and maximum mixing is favored.