Muon track reconstruction and data selection techniques in AMANDA Ahrens, J.; Bai, X.; Bay, R. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2004, Letnik:
524, Številka:
1
Journal Article
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The Antarctic Muon And Neutrino Detector
Array (AMANDA) is a high-energy neutrino telescope operating at the geographic South Pole. It is a lattice of photo-multiplier tubes buried deep in the polar ...ice between 1500 and
2000
m
. The primary goal of this detector is to discover astrophysical sources of high-energy neutrinos. A high-energy muon neutrino coming through the earth from the Northern Hemisphere can be identified by the secondary muon moving upward through the detector.
The muon tracks are reconstructed with a maximum likelihood method. It models the arrival times and amplitudes of Cherenkov photons registered by the photo-multipliers. This paper describes the different methods of reconstruction, which have been successfully implemented within
AMANDA. Strategies for optimizing the reconstruction performance and rejecting background are presented. For a typical analysis procedure the direction of tracks are reconstructed with about 2° accuracy.
We present the results of a search for point sources of high-energy neutrinos in the northern hemisphere using AMANDA-II data collected in the year 2000. Included are flux limits on several ...active-galactic-nuclei blazars, microquasars, magnetars, and other candidate neutrino sources. A search for excesses above a random background of cosmic-ray-induced atmospheric neutrinos and misreconstructed downgoing cosmic-ray muons reveals no statistically significant neutrino point sources. We show that AMANDA-II has achieved the sensitivity required to probe known TeV gamma-ray sources such as the blazar Markarian 501 in its 1997 flaring state at a level where neutrino and gamma-ray fluxes are equal.
A search for an excess of muon–neutrinos from neutralino annihilations in the Sun has been performed with the AMANDA-II neutrino detector using data collected in 143.7 days of live-time in 2001. No ...excess over the expected atmospheric neutrino background has been observed. An upper limit at 90% confidence level has been obtained on the annihilation rate of captured neutralinos in the Sun, as well as the corresponding muon flux limit at the Earth, both as functions of the neutralino mass in the range 100–5000
GeV.
Data from the AMANDA-B10 detector taken during the austral winter of 1997 have been searched for a diffuse flux of high energy extraterrestrial muon neutrinos. This search yielded no excess events ...above those expected from background atmospheric neutrinos, leading to upper limits on the extraterrestrial neutrino flux measured at the earth. For an assumed E-2 spectrum, a 90% classical confidence level upper limit has been placed at a level E2Phi(E)=8.4 x 10(-7) cm(-2) s(-1) sr(-1) GeV (for a predominant neutrino energy range 6-1000 TeV), which is the most restrictive bound placed by any neutrino detector. Some specific predicted model spectra are excluded. Interpreting these limits in terms of the flux from a cosmological distributions of sources requires the incorporation of neutrino oscillations, typically weakening the limits by a factor of 2.
Transient neutrino sources such as gamma-ray bursts (GRB) and supernovae (SNe) are hypothesized to emit bursts of high-energy neutrinos on a time-scale of ...100 s. While GRB neutrinos would be ...produced in high relativistic jets, core-collapse SNe might host soft-relativistic jets, which become stalled in the outer layers of the progenitor star leading to an efficient production of high-energy neutrinos. To increase the sensitivity to these neutrinos and identify their sources, a low-threshold optical follow-up program for neutrino multiplets detected with the IceCube observatory has been implemented. If a neutrino multiplet, ie two or more neutrinos from the same direction within 100 s, is found by IceCube a trigger is sent to the Robotic Optical Transient Search Experiment (ROTSE). The 4 ROTSE telescopes immediately start an observation program of the corresponding region of the sky in order to detect an optical counterpart to the neutrino events. No statistically significant excess in the rate of neutrino multiplets has been observed and furthermore no coincidence with an optical counterpart was found. (ProQuest: ... denotes formulae/symbols omitted.)
We report on a search for electro-magnetic and/or hadronic showers (cascades) induced by high-energy neutrinos in the data collected with the AMANDA II detector during the year 2000. The observed ...event rates are consistent with the expectations for atmospheric neutrinos and muons. We place upper limits on a diffuse flux of extraterrestrial electron, tau and muon neutrinos. A flux of neutrinos with a spectrum Φ∝E−2 which consists of an equal mix of all flavors, is limited to E2Φ(E)=8.6×10−7 GeVcm−2s−1sr−1 at a 90% confidence level for a neutrino energy range 50 TeV to 5 PeV. We present bounds for specific extraterrestrial neutrino flux predictions. Several of these models are ruled out.
Data taken during 1997 with the AMANDA-B10 detector are searched for a diffuse flux of neutrinos of all flavors with energies above 1016eV. At these energies the Earth is opaque to neutrinos, and ...thus neutrino induced events are concentrated at the horizon. The background are large muon bundles from down-going atmospheric air shower events. No excess events above the background expectation are observed and a neutrino flux following E−2, with an equal mix of all flavors, is limited to E2Φ(1015eV<E<3×1018eV)⩽0.99×10−6GeVcm−2s−1sr−1 at 90% confidence level. This is the most restrictive experimental bound placed by any neutrino detector at these energies. Bounds to specific extraterrestrial neutrino flux predictions are also presented.
A comparison of the forward-backward s-quark asymmetry with the b-quark asymmetry can be used to test the universality of the standard model coupling constants, We present a measurement of the ...s-quark asymmetry at the Z(o) peak using high energy charged k
Using the South Pole Acoustic Test Setup (SPATS) and a retrievable transmitter deployed in holes drilled for the IceCube experiment, we have measured the attenuation of acoustic signals by South Pole ...ice at depths between 190 m and 500 m. Three data sets, using different acoustic sources, have been analyzed and give consistent results. The method with the smallest systematic uncertainties yields an amplitude attenuation coefficient α = 3.20 ± 0.57 km-1 between 10 and 30 kHz, considerably larger than previous theoretical estimates. Expressed as an attenuation length, the analyses give a consistent result for λ ≡ 1/α of ˜300 m with 20% uncertainty. No significant depth or frequency dependence has been found.
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