Development of a sub-glacial array of radio antennas for the detection of the flux of GZK neutrinos

• Main Author: Meures, Thomas
• Other Authors: Hanson, Kael, Tiniakov, Petr, Buitink, Stijn, De Lentdecker, Gilles, Scholten, Olaf
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Universite Libre de Bruxelles 2014
• Subjects: Physique; Neutrinos; Radio detectors; Démodulateurs; radio detection; Askaryan radiation; GZK neutrinos; South Pole; South pole
• Online Access: http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209032; https://dipot.ulb.ac.be/dspace/bitstream/2013/209032/1/02fc3751-b23c-4692-8709-5659cb88a456.txt

GZK neutrino are interesting messenger particles since, if detected, they can transmit us exclusive information about ultra-high energy processes in the Universe. These particles, which hold energies above 10^16 eV, interact very rarely. Therefore, detectors of several gigatons of matter are needed to discover them. The ARA detector is planned and currently being constructed at the South Pole. It is designed to use the Askaryan effect, the emission of radio waves from neutrino induced cascades in the South Pole ice, to detect neutrino interactions. With antennas distributed in 37 stations in the ice, such interactions can be observed in a volume of several hundred cubic kilometers. Currently 2 ARA stations have been deployed in the ice and are taking data since the beginning of the year 2013. The first part of this thesis summarizes the current theories concerning the GZK mechanism and the Askaryan effect to explain the interest in GZK neutrinos and in the used detection method. In the second part the ARA detector is described and calibrations of different detector parts are presented. In this work, the digitization chips have been calibrated concerning their timing precision and signal amplitude. In this way a timing precision of 100 ps between antennas could be achieved. Furthermore, the geometry of the antenna clusters is determined by cuts based on external signals to allow for a proper radio vertex reconstruction. In the third part of the thesis the development of methods to distinguish radio signals from thermal noise are presented. Moreover, a reconstruction method, developed to determine the position of radio sources, is described. With only two stations operational a discovery of GZK neutrinos is not expected and in fact no signal candidate has been found in the analysis of the data. A neutrino ux limit is calculated. This limit is not competitive yet with the current best limits, but very promising for the full ARA detector. The work shows that after completion this detector is expected to be capable ...