Identifying cosmic ray induced cascade events with IceTop

IceCube is the largest neutrino detector in the world. It consists of an array of photomultiplier tubes installed throughout a cubic kilometre of ice below the surface at the South Pole. These photomultiplier tubes detect the Cherenkov radiation from neutrino-nucleon interactions. IceTop is the surface component of IceCube neutrino observatory and is used to study Cosmic Ray Extensive Air Showers (EAS). The goal of IceCube is to investigate astophysical neutrinos. However the majority of events recorded by IceCube are background events caused by cosmic rays interacting in the Earth's atmosphere. This thesis is concerned with developing a technique to veto the background events from the IceCube experimental data using the IceTop surface array. Four original studies were performed. In the rst study the output of a cosmic-ray air shower simulation code was compared with real events detected by IceCube and IceTop. It was found that the simulation code performed well, although in some cases the actual number of hits detected in IceTop ws greater than predicted. However as far as assessing the ability of IceTop as a veto this means our estimates will be conservative which would mean that the veto would be more e ective than estimated. In the second study the cosmic-ray simulation code was used to investigate the scope of background events which might be able to vetoed using the IceTop array and the energies and zenith angles where the veto would be e ective were given. The appropriate time window for deciding whether an IceTop hit was related to an event detected in the IceCube detector was investigated in the third study and was found to be -500 ns to 800 ns relative to the timing of the IceCube event. In the fourth study, the nal sample of a published IceCube cascade analysis was examined to determine whether there were any related hits in the IceTop array