Unfolding the True Atmospheric Neutrino Event Rate in the 1Gev -- 1Tev Range Using IceCube/DeepCore

Abstract

An unfolding measurement of the atmospheric neutrino flux at the South Pole is performed using the IceCube/DeepCore detector. The main results presented is the true neutrino interaction rate by unit volume of ice, as a function of energy or zenith angle. The method used is the D'Agostini iterative unfolding. While the detector response estimate is based on Monte Carlo simulation, the iterative approach will compensate for this inherent bias and draw the unfolded result closer to the unbiased estimator, as the number of iterations is optimized. This is done using an ensemble test with a blind re-smearing approach. Thus this measurement is minimally biased regarding atmospheric flux-, oscillation- and neutrino interaction models, allowing model builders to test their predictions against this measurement. As an aside, using the same data set and methodology, we also present an unfolding measurement directly to atmospheric neutrino flux.