The IceCube Neutrino Observatory was designed primarily to search for high-energy (TeV–PeV) neutrinos produced in distant astrophysical objects. A search for >100 TeV neutrinos interacting inside the instrumented volume has recently provided evidence for an isotropic flux of such neutrinos. At lower energies, IceCube collects large numbers of neutrinos from the weak decays of mesons in cosmic-ray air showers. Here we present the results of a search for neutrino interactions inside IceCube’s instrumented volume between 1 TeV and 1 PeV in 641 days of data taken from 2010–2012, lowering the energy threshold for neutrinos from the southern sky below 10 TeV for the first time, far below the threshold of the previous high-energy analysis. Astrophysical neutrinos remain the dominant component in the southern sky down to a deposited energy of 10 TeV.
From these data we derive new constraints on the diffuse astrophysical neutrino spectrum,as well as the strongest upper limit yet on the flux of neutrinos from charmed-meson decay in the atmosphere, 1.52 times the benchmark theoretical prediction used in previous IceCube results at 90% confidence.
Read the paper on the arXiv.
Search for contained neutrino events at energies greater than 1 TeV in 2 years of data.
Click here to download (.zip, 2.3MB)
The download includes the following files:
Neutrino effective areas in m2 for the entire event selection. To predict the total number of events that would have appeared in this sample from your favorite flux, integrate your flux model over the provided neutrino energy and zenith angle bins to obtain a rate of events per m2, multiply by the provided effective areas, and take the sum over all neutrino energy and zenith angle bins.
Note that the quoted effective area is an average for neutrinos and antineutrinos. To obtain the correct number of events, multiply by the sum of the neutrino and antineutrino fluxes.
Effective areas in m2 for each bin shown in Fig. 8, separated by particle type, interaction channel (charged-current deep-inelastic scattering (CC), neutral current DIS (NC), or resonant anti-electron-neutrino/electron scattering (GR)), and event signature (track or cascade, using the same classification as the event table shown below). Using these tables instead of the total effective areas given above allows you to predict the deposited-energy spectrum observed in this analysis separately for the northern and southern hemispheres.
Note that in contrast to the integrated tables above, these effective areas are given separately for neutrinos and anti-neutrinos, and so should be multiplied by a neutrino or anti-neutrino flux.
Reconstructed deposited energies and declination for the 383 events with successful energy reconstructions. Each of the error ranges given is 68% confidence interval derived from Monte Carlo simulation, assuming the given flux (conventional atmospheric neutrinos, the best-fit 1:1:1 E-2.47 astrophysical neutrino flux, or the typical 1:1:1 E-2 benchmark flux).
Data points from Fig. 12
Models and data points from Fig. 8
NB: the energy is resonstructed deposited energy, not neutrino energy
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