20 research outputs found
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
Search for Supernova Neutrino-Bursts with the AMANDA Detector
The core collapse of a massive star in the Milky Way will produce a neutrino
burst, intense enough to be detected by existing underground detectors. The
AMANDA neutrino telescope located deep in the South Pole ice can detect MeV
neutrinos by a collective rate increase in all photo-multipliers on top of dark
noise. The main source of light comes from positrons produced in the
CC-reaction of anti-electron neutrinos on free protons \antinue + p \to e^+ +
n. This paper describes the first supernova search performed on the full sets
of data taken during 1997 and 1998 (215 days of live time) with 302 of the
detector's optical modules. No candidate events resulted from this search. The
performance of the detector is calculated, yielding a 70% coverage of the
Galaxy with one background fake per year with 90% efficiency for the detector
configuration under study. An upper limit at the 90% c.l. on the rate of
stellar collapses in the Milky Way is derived, yielding 4.3 events per year. A
trigger algorithm is presented and its performance estimated. Possible
improvements of the detector hardware are reviewed.Comment: 20 pages, 14 figures. Submitted to Astroparticle Physic
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Characteristics of Irreversibly Constricted Cerebral Blood Vessels
Cerebral vasospasm is a biphasic event resulting in most cases in an irreversibly constricted cerebral blood vessel. The major initiator of vasoconstriction is subarachnoid hemorrhage (SAH) or trauma. Several animal models have been developed but none approximates the pathological sequellae seen in man after SAH. We have refined a dog SAH model which possesses many of the physiological and ultrastructural features seen in man after SAH induced vasospasm and report some clinically relevant findings