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480m 190m Depth 810m ice surface level 1000m 1520m 2000m A B 60m 60m B Electronic feedthrough Main cable Optical fiber 3 Nylon ball 1 4 60m 2 Voltage divider Metallic harness Silicon gel Photomultiplier Glass sphere Figure 25: Geometries of the AMANDA-A and AMANDA-B4 arrays with a zoomed-in view of an optical module of the B-array. 36
5 Optical properties of the South Polar ice 5.1 Diffusive scattering in AMANDA-A Several light sources have been installed in-situ in order to assess the optical properties of the glacier ice in which the different stages of the AMANDA array are deployed. One concern is that photons would get scattered on air bubbles or dust and the Cherenkov cone get deformed, another is to find which depth has the clearest ice. As air bubbles trapped in the accumulating snow get buried deeper with time, their size diminishes due to the increasing pressure. Eventually a phase transition occurs, in which hydrate crystals are formed and no bubbles can be observed [48]. Ice cores taken at the Russian Vostok Antarctic base reported bubble free ice at depths below 1280 m [49], and cores taken at Byrd station yielded bubble free ice below 1100 m [50]. Preliminary studies by AMANDA, made with a single string containing four OMs, indicated negligible scattering by air bubbles or dust in the ice at 800 m depth [51]. For AMANDA-A, measurements of time-distributions of light emitted from the sources deployed and detected by OMs further away (typically by tenths of meters) did not result in a sharp peak which would indicate clear ice. Instead, they yielded broad curves extending over several microseconds, characteristic of scattering by air bubbles (see Fig. 26) delaying the arrival times of the photons. The AMANDA-A array is located at depths between 810 m and 1000 m, with the geometry shown in Fig. 25. Figure 26: Arrival time distribution at an OM located 32 m away from the source. The straight line indicates where unscattered photons would have hit the cathode. The data, represented with dots, is fitted by the thick curve and the histogram represents the Monte Carlo simulation. Since the time distributions recorded indicate that photons undergo several scatterings along their path, the situation can be best described by a random walk process [52]. The Green’s function for an isotropic light source can be derived in the limiting case when the distance between emitter and receiver of light is large compared to the mean distance between scatterings ( ¤ in ¤ the case of bubbles): ¤ ¤ ¦ ¢ ¤ ¤ § £ ¤ ¤ ¤ 37 (42)
Page 1 and 2: Muon Analysis with the AMANDA-B Fou
Page 3 and 4: Contents 1 Dissertation description
Page 5 and 6: 1 Dissertation description This dis
Page 7 and 8: structure of NESTOR is a 12 floor t
Page 9 and 10: 3.1.2 Acceleration mechanisms In pr
Page 11 and 12: 3.1.3 Candidate point sources of ne
Page 13 and 14: 3.1.4 Neutrino cascades ~10 -2 pc J
Page 15 and 16: 3.1.6 Background The first source o
Page 17 and 18: which is the fraction of the nucleo
Page 19 and 20: Detection rate Detector Figure 7: D
Page 21 and 22: Cherenkov wavefront £ £ £¤¦¥
Page 23 and 24: Electromagnetic showers Both electr
Page 25 and 26: 4 Detector description 4.1 String d
Page 27 and 28: Figure 10: ©¡ -laser module insta
Page 29 and 30: 1m Figure 12: The drill head, equip
Page 31 and 32: Figure 14: Bleeder circuit meters.
Page 33 and 34: micros. Figure 16: Arrival time dis
Page 35 and 36: 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1
Page 37 and 38: of 100 V over PMs. The TDC module u
Page 39: 10 4 10 3 10 2 0 5000 10000 15000 2
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
Page 55 and 56: £ £ £ £ £ £ 79.5 72.0 80.3
Page 57 and 58: String# 2 3 4 1 1.9 1.8 -51.5 1.5
Page 59 and 60: String# 2 3 4 1 0.2 1.0 -51.5 0.9
Page 61 and 62: experience from the field, where th
Page 63 and 64: emitter ¦ £ ¤ ¢ ¡ ¦ £ ¤ ¢
Page 65 and 66: 1 ¢ ¢ ¢ ¢ ¢ ¢ ¥ ¢ ¢ ¢ ¢
Page 67 and 68: 7 Data filters 7.1 Data cleaning Th
Page 69 and 70: Figure 46: All leading edge times f
Page 71 and 72: the average relative time between p
Page 73 and 74: 8 Reconstruction of muons-tracks 8.
Page 75 and 76: x' z' D č Figure 51: In a coordina
Page 77 and 78: Number of events 1200 1000 800 600
Page 79 and 80: Probability (t > t 0 ) 1 0.8 0.6 0.
Page 81 and 82: 1/N dN/dt < t > (ns) Skewness 1 0.8
Page 83 and 84: Several measures of the distributio
Page 85 and 86: ¤ ¦ § £ ¢¡ ¤£ ¢¡ § ¤
Page 87 and 88: Table 15 yields the results, with n
Page 89 and 90: Figure 60: £¢¡ ¤¤£¦¥¨§©
Page 91 and 92:
9 Analysis of 1996 data There are t
Page 93 and 94:
Figure 64: Atmospheric muon flux at
Page 95 and 96:
ule to scatter back and give a hit,
Page 97 and 98:
£ ¡ ¤¨£ £ ¦¡ Figure 70: for
Page 99 and 100:
9.2.2 SPASE coincidences The SPASE
Page 101 and 102:
-15 and 15 ns after the STREC recon
Page 103 and 104:
9.3 Search for atmospheric neutrino
Page 105 and 106:
Figure 78: Left: probability distri
Page 107 and 108:
Figure 80: Distributions of several
Page 109 and 110:
8 7 6 5 4 3 2 1 Figure 82: The two
Page 111 and 112:
threshold for an AMANDA-B4 search o
Page 113 and 114:
¡ [ ¦ Neutralino 50 100 250
Page 115 and 116:
10 Conclusions A position calibrati
Page 117 and 118:
References [1] E. Andrés, P. Askeb
Page 119 and 120:
[50] A. J. Gow and T. Williamson, J
Page 121 and 122:
Appendix correction (ns) correction
Page 123 and 124:
Em. string Em. module Rec. string R
Page 125 and 126:
distance (m) Run 159 Z-shift=33.5.
Page 127 and 128:
distance (m) To string 1 distance (
Page 129 and 130:
distance (m) To string 1 distance (
Page 131 and 132:
¦ ¦ § ¦ © © © © ¢ ¡£¢
Page 133 and 134:
Em. string Em. module Rec. string R
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