Analysis of Ice Cherenkov detector response functions during a latitude survey

Abstract

Ice Top, the surface component of IceCube Neutrino Observatory at the South Pole, detects cosmic ray air showers with an array of Ice Cherenkov detectors called"IceTop Tanks."We examine data from an IceTop Tank contained in an insulated shipping con- tainer loaded on the Swedish Oden icebreaker, in November 2009, with the collaboration from the University of Delaware, UW River Falls, and Uppsala University. Oden tra- versed the Atlantic Ocean from Helsingborg, Sweden, to MeMurdo Station, Antarctica, and returned. In a latitude survey, a detector is carried through a wide range of geo- magnetic cutoffs. At each location on the surface of the Earth, the geomagnetic cutoff is the minimum rigidity (momentum per unit charge) that a particle needs to reach the top of the atmosphere from interplanetary space. The project aims to calibrate the Ice- Top 'Tanks to study cosmic rays in the GeV energy range using the Earth as a magnet spectrometer. Specifically we determine the Ice Cherenkov detector response functions during this survey year. Due to solar modulation changes during the trip, we separate the analysis into two intervals (southbound and northbound). The data are fitted using Dorman functions from which the response functions are calculated. Further analysis will allow the energy-dependent effective area (yield functions) of the tanks to be determined.