A Search for Neutrino-Induced Electromagnetic Showers in the 2008 Combined IceCube and AMANDA Detectors

Open Access
Author:
Rutledge, Douglas Lowery
Graduate Program:
Physics
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
July 21, 2011
Committee Members:
  • Douglas Cowen, Dissertation Advisor
  • Douglas Cowen, Committee Chair
  • Mark Strikman, Committee Member
  • Stephane Coutu, Committee Member
  • Robin Bruce Ciardullo, Committee Member
Keywords:
  • IceCube
  • AMANDA
  • atmospheric neutrino
Abstract:
The Antarctic Muon and Neutrino Detector Array (AMANDA) and its successor experiment, IceCube, are both Cherenkov detectors deployed very near the geographic South Pole. The Cherenkov technique uses the light emitted by charged particles that travel faster than the propagation velocity of light in the detector medium. This can be used to detect the daughter particles from the interaction in the ice of neutrinos of all flavors. The topology of neutrino interaction events is strongly dependent on the neutrino flavor, allowing separate measurements to be made. Electrons resulting from neutrino interactions leave spherical events by depositing all of their energy within a small region. Events of this type are often referred to as “Cascades.” Muons propagate over long distances, leaving Cherenkov light distributed over a line. The principal event topology for taus is called “Double Bangs,” with two spatially separated cascades. There are many potential benefits to running a search for neutrino-induced cascades using the combined readout from both the IceCube and the AMANDA detectors. AMANDA is sensitive to lower energies, owing to its denser distribution of PMTs. IceCube has a much larger volume, allowing it to make better measurements of the background. This allows for better background rejection techniques, and thus a higher final signal rate. This work presents a search for cascades from the atmospheric neutrino flux using the combined data from AMANDA’s Transient Waveform Recorder (TWR) data acquisition system, and IceCube’s 40 string detector configuration. After the 200 Hz background rate is removed the final measured rate of cascade candidates is 2.5 × 10−7 Hz+3.8×10−7 −9.9×10−8 Hz(stat) ± 9.8 × 10−8 Hz(syst). The dataset used in this work was collected over 187 days from April to November in 2008.