Licentiate Thesis: Preparations for the next solar WIMP Analysis with IceCube
Friday 21 February 2014
to 12:00 at
Marcel Zoll (Stockholm University, Department of Physics)
In the year 2011 the construction of IceCube, a neutrino observatory buried in deep clear Antarctic ice, was completed. IceCube now consists of an array of 5160 digital light detection modules assembled on 86 strings, which encloses a instrumented volume of roughly 1 km3 optimized for detection of neutrinos down to energies of 100 GeV. In this detector eight of these strings are arranged in a denser conﬁguration of the low energy extension DeepCore, which pushes the neutrino energy threshold further down to 10 GeV. This allows probing for ﬂuxes from various astrophysical sources. Of special interest in context of Dark Matter theories is the Sun as a potential source of energetic neutrinos. There neutrinos can be messenger particles created in annihilations of trapped Dark Matter particles (WIMPs). Searches for solar WIMPs have a tradition in IceCube and shall be continued with data recorded in the completed detector conﬁguration (IC86). Since the detector conﬁguration does not substantially change further, it is worthwhile to revisit, investigate and reﬁne analysis methods developed during the construction phases and improve on them. Described in this thesis is the preparation work for such an improved analysis: ﬁlter and data treatment studies have been conducted during three years ensuring the quality of the experimental data stream. In parallel the simulation codes ’WimpSim’ and ’WimpSim-Reader’ have been improved, which provide the signal deﬁnition for solar WIMP studies. Also in an extensive investigation about event splitting and hit clustering algorithms has been conducted. This yielded an alternative event splitting and recombination approach using ’MaxDist-Splitter’ and ’CoincidentSuite’. In a subsequent study it could be shown that thereby the performance was increased compared to previous solutions by up to 50%. Also the general beneﬁt of these alternative solutions for general data processing has been investigated, which can remedy so far unregarded problems in lowest level data treatment. Furthermore the analysis strategy has been reviewed and adjusted to the new conditions, which is expected to bring further improvements. By this work the foundation for the next solar WIMP analysis has been laid and the achieved improvements are expected to improve the sensitivity.