Investigation into the anomalous trigger rates in the IceCube Neutrino Observatory on Febraury 5th 2013

• Main Authors: Olofsson, Simon, Setterquist, Erik
• Format: Bachelor Thesis
• Language: English
• Published: 2013
• Subjects: IceCube; South Pole; South pole
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-202219

On February 5th 2013, a 9.09σ deviation in noise and muon triggerrates lasting 1.5s was detected in the IceCube Neutrino Observatoryon the South Pole, which triggered a supernova alert. Thisinvestigation has studied the noise and angular distributions of the9.09σ alert and compared it to the normal background. For the noisestudy, we looked at the noise distributions of three different levels:for the whole detector, for each string, and for each digital opticalmodule. The distributions were fitted with Gaussian and lognormalfunctions to determine if any anomalies could be detected. For theangular distribution study, the online filter passing rates were studiedto determine the probability for each filter’s passing rate during the9.09σ alert. The angular study then moved on to perform a binnedpoint-source analysis of both the full data set and the filtered dataset. Conclusions are that a) the noise increase is most pronounced inthe core of the detector, but this is consistent with the overallincrease in the detector, b) no increase in extremely high-energymuon events could be found, and c) the increase in muon eventsdoes not seem to be coming from a particular region of the sky.