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9.4 Search for neutralinos from the center of the Earth ¡ ¢ ¡ ¢ ¡ £ ¤ £ ¡ ¢ ¡ ¡ ¢ ¡ 104 10 Conclusions 111 Acknowledgments 112 References 113 Appendix 117
1 Dissertation description This dissertation describes the work done between the summer of 1993 and the summer of 1997. It includes: - a summary of the physics goals of AMANDA. - a description of the hardware used in the detector. - a summary of our present knowledge about the optical properties of the glacier ice at the South Pole. - results of the position and time calibration of the AMANDA-B array. - a description of the data preparation prior to reconstruction. - a description of the muon-track reconstruction methods used and a discussion upon the detector response to different classes of events. - studies of atmospheric muon coincidences between SPASE-2 and AMANDA-B. - a search for up-going atmospheric neutrinos. - the results of a search for muons induced by neutralino annihilation from the center of the Earth, resulting in a limit on the expected flux. My main activities in the AMANDA collaboration were the development of the Swedish event reconstruction program STREC. I have also worked with the position calibration of the fourstring array, especially using laser data, with the data-handling and with the analysis of the AMANDA-SPASE events. I also applied the reconstruction program in the search for atmospheric neutrinos, using the whole 1996 data sample. This served as a basis for the neutralino analysis, resulting in limits set on the neutrino-induced muon flux coming from neutralino annihilation in the center of the Earth. 2 Introduction AMANDA is a European-American collaboration to build a neutrino telescope located at the geographical South Pole, a project started in 1992. Such a telescope will open a new observation window on the Universe, complementary to the electromagnetic observations already in use. Its basic principle is to detect the Cherenkov wavefront emitted by muons passing through a clear medium, which are produced when highly energetic neutrinos (greater than a few GeV) interact with matter in a region close to the detector. This light is detected by an array of photo-multipliers (PMs) buried in deep glacier ice. The time distribution of hits then provides the necessary information for reconstructing the straight-line track of the muon. One can infer the direction of incoming neutrinos from the direction of their muon tracks since the two are parallel within about one degree at about 1 TeV (and improving with energy). Thus the telescope is able to search for point sources of neutrinos with an angular resolution of order one degree or better. The general aim is to observe high energy cosmic neutrinos from different possible sources such as Active Galactic Nuclei (AGNs), X-ray binary systems, young supernova remnants, Gamma Ray Bursters (GRBs) and neutralino annihilation in the center of our Sun and Earth. 1
Page 1 and 2: Muon Analysis with the AMANDA-B Fou
Page 3: Contents 1 Dissertation description
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Page 13 and 14: 3.1.4 Neutrino cascades ~10 -2 pc J
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Page 23 and 24: Electromagnetic showers Both electr
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Page 37 and 38: of 100 V over PMs. The TDC module u
Page 39 and 40: 10 4 10 3 10 2 0 5000 10000 15000 2
Page 41 and 42: 5 Optical properties of the South P
Page 43 and 44: λ a [m] 300 250 200 150 100 50 Dep
Page 45 and 46: (a.u) 0.5 0.4 0.3 0.2 0.1 0 0 1000
Page 47 and 48: absorption length, m 160 140 120 10
Page 49 and 50: leading edge (ns) Figure 34: Exampl
Page 51 and 52: High Voltage [V] Gain 1300 0.03 140
Page 53 and 54: transit time (ns) YAG-data, larger
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experience from the field, where th
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7 Data filters 7.1 Data cleaning Th
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Figure 46: All leading edge times f
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the average relative time between p
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8 Reconstruction of muons-tracks 8.
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x' z' D č Figure 51: In a coordina
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Number of events 1200 1000 800 600
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Probability (t > t 0 ) 1 0.8 0.6 0.
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1/N dN/dt < t > (ns) Skewness 1 0.8
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Several measures of the distributio
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Table 15 yields the results, with n
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9 Analysis of 1996 data There are t
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Figure 64: Atmospheric muon flux at
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ule to scatter back and give a hit,
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£ ¡ ¤¨£ £ ¦¡ Figure 70: for
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9.2.2 SPASE coincidences The SPASE
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-15 and 15 ns after the STREC recon
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9.3 Search for atmospheric neutrino
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Figure 78: Left: probability distri
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Figure 80: Distributions of several
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8 7 6 5 4 3 2 1 Figure 82: The two
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threshold for an AMANDA-B4 search o
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¡ [ ¦ Neutralino 50 100 250
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10 Conclusions A position calibrati
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References [1] E. Andrés, P. Askeb
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[50] A. J. Gow and T. Williamson, J
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Appendix correction (ns) correction
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Em. string Em. module Rec. string R
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distance (m) Run 159 Z-shift=33.5.
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distance (m) To string 1 distance (
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distance (m) To string 1 distance (
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Em. string Em. module Rec. string R
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