493 research outputs found
Functional responses can unify invasion ecology.
We contend that invasion ecology requires a universal, measurable trait of species and their interactions with resources that predicts key elements of invasibility and ecological impact; here, we advocate that functional responses can help achieve this across taxonomic and trophic groups, among habitats and contexts, and can hence help unify disparate research interests in invasion ecology
Results from the Antarctic Muon and Neutrino Detector Array (AMANDA)
We show new results from both the older and newer incarnations of AMANDA
(AMANDA-B10 and AMANDA-II, respectively). These results demonstrate that AMANDA
is a functioning, multipurpose detector with significant physics and
astrophysics reach. They include a new higher-statistics measurement of the
atmospheric muon neutrino flux and preliminary results from searches for a
variety of sources of ultrahigh energy neutrinos: generic point sources,
gamma-ray bursters and diffuse sources producing muons in the detector, and
diffuse sources producing electromagnetic or hadronic showers in or near the
detector.Comment: Invited talk at the XXth International Conference on Neutrino Physics
and Astrophysics (Neutrino 2002), Munich, Germany, May 25-30, 200
IceCube - the next generation neutrino telescope at the South Pole
IceCube is a large neutrino telescope of the next generation to be
constructed in the Antarctic Ice Sheet near the South Pole. We present the
conceptual design and the sensitivity of the IceCube detector to predicted
fluxes of neutrinos, both atmospheric and extra-terrestrial. A complete
simulation of the detector design has been used to study the detector's
capability to search for neutrinos from sources such as active galaxies, and
gamma-ray bursts.Comment: 8 pages, to be published with the proceedings of the XXth
International Conference on Neutrino Physics and Astrophysics, Munich 200
The AMANDA Neutrino Telescope
With an effective telescope area of order m for TeV neutrinos, a
threshold near 50 GeV and a pointing accuracy of 2.5 degrees per muon
track, the AMANDA detector represents the first of a new generation of high
energy neutrino telescopes, reaching a scale envisaged over 25 years ago. We
describe early results on the calibration of natural deep ice as a particle
detector as well as on AMANDA's performance as a neutrino telescope.Comment: 12 pages, Latex2.09, uses espcrc2.sty and epsf.sty, 13 postscript
files included. Talk presented at the 18th International Conference on
Neutrino Physics and Astrophysics (Neutrino 98), Takayama, Japan, June 199
Sensitivity of the IceCube Detector to Astrophysical Sources of High Energy Muon Neutrinos
We present the results of a Monte-Carlo study of the sensitivity of the
planned IceCube detector to predicted fluxes of muon neutrinos at TeV to PeV
energies. A complete simulation of the detector and data analysis is used to
study the detector's capability to search for muon neutrinos from sources such
as active galaxies and gamma-ray bursts. We study the effective area and the
angular resolution of the detector as a function of muon energy and angle of
incidence. We present detailed calculations of the sensitivity of the detector
to both diffuse and pointlike neutrino emissions, including an assessment of
the sensitivity to neutrinos detected in coincidence with gamma-ray burst
observations. After three years of datataking, IceCube will have been able to
detect a point source flux of E^2*dN/dE = 7*10^-9 cm^-2s^-1GeV at a 5-sigma
significance, or, in the absence of a signal, place a 90% c.l. limit at a level
E^2*dN/dE = 2*10^-9 cm^-2s^-1GeV. A diffuse E-2 flux would be detectable at a
minimum strength of E^2*dN/dE = 1*10^-8 cm^-2s^-1sr^-1GeV. A gamma-ray burst
model following the formulation of Waxman and Bahcall would result in a 5-sigma
effect after the observation of 200 bursts in coincidence with satellite
observations of the gamma-rays.Comment: 33 pages, 13 figures, 6 table
Muon Track Reconstruction and Data Selection Techniques in AMANDA
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 1500m and 2000m.
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 degree accuracy.Comment: 40 pages, 16 Postscript figures, uses elsart.st
On the selection of AGN neutrino source candidates for a source stacking analysis with neutrino telescopes
The sensitivity of a search for sources of TeV neutrinos can be improved by
grouping potential sources together into generic classes in a procedure that is
known as source stacking. In this paper, we define catalogs of Active Galactic
Nuclei (AGN) and use them to perform a source stacking analysis. The grouping
of AGN into classes is done in two steps: first, AGN classes are defined, then,
sources to be stacked are selected assuming that a potential neutrino flux is
linearly correlated with the photon luminosity in a certain energy band (radio,
IR, optical, keV, GeV, TeV). Lacking any secure detailed knowledge on neutrino
production in AGN, this correlation is motivated by hadronic AGN models, as
briefly reviewed in this paper.
The source stacking search for neutrinos from generic AGN classes is
illustrated using the data collected by the AMANDA-II high energy neutrino
detector during the year 2000. No significant excess for any of the suggested
groups was found.Comment: 43 pages, 12 figures, accepted by Astroparticle Physic
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