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Abstract
Exploding stars, or supernovae, are among the most cataclysmic events observed. The detection of supernova neutrinos from SN1987A marked the beginning of a new type of astronomy-neutrino astronomy. The observation of O(10 MeV) neutrinos from the next galactic core-collapse supernova will provide invaluable insight into the supernova explosion process and may provide information about the elusive nature of neutrinos. The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector designed to detect astrophysical neutrinos with energies ≥100GeV. With its supernova analysis timing resolution (2ms) and high event statistics (O(105–10 6)) per galactic supernova, it takes a central part in the current efforts to detect neutrinos from the next galactic supernova. A new simulation framework is presented here. This implementation is able to provide the full detector response in the case of a galactic core-collapse supernova. It is based on statistical weighting techniques already employed in other IceCube simulation. Over the course of the last three years of operations of the completed IceCube detector, an increasing sensitivity to the atmospheric muon background has been observed. A 48.2% increase in the number of false positive triggers induced by the atmospheric muon background in the first two years of the completed detector has been observed. A ∼3.5% decrease in the noise rate produces a ∼2% increase in sensitivity to atmospheric muons. This in turn causes an increasing number of false positive triggers. The decay in the baseline noise is attributed to effects of the re-freezing process of the ice after the detector has been constructed. The impact of using data with a lower threshold is investigated from a small subset of the data. Using the lower energy trigger, this increases the estimate of the number of DOM triggers caused atmospheric muons by ∼6.5%. This will not affect current atmospheric muon subtraction methods employed in the analysis running at the South Pole.
