Search results for "NEUTRINO"
showing 10 items of 1752 documents
Search for Extraterrestrial Point Sources of Neutrinos with AMANDA-II
2003
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 AGN 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.
Search for high energy cosmic muon neutrinos from variable gamma-ray sources and time calibration of the optical modules of the ANTARES telescope
2015
325 páginas. Tesis Doctoral del Departamento de Física Atómica, Molecular y Nuclear de la Universidad de Valencia y del Instituto de Física Corpuscular (IFIC).
Search for neutrino emission from gamma-ray flaring blazars with the ANTARES telescope
2012
The ANTARES telescope observes a full hemisphere of the sky all the time with a duty cycle close to 100%. This makes it well suited for an extensive observation of neutrinos produced in astrophysical transient sources. In the surrounding medium of blazars, i.e. active galactic nuclei with their jets pointing almost directly towards the observer, neutrinos may be produced together with gamma-rays by hadronic interactions, so a strong correlation between neutrinos and gamma-rays emissions is expected. The time variability information of the studied source can be obtained by the gamma-ray light curves measured by the LAT instrument on-board the Fermi satellite. If the expected neutrino flux ob…
Measurement of acoustic attenuation in South Pole ice
2010
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 alpha = 3.20 \pm 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 lambda = 1/alpha of ~1/300 m with 20% uncertainty. No significant depth or …
Neutrino pair annihilation near accreting, stellar-mass black holes
2006
We investigate the energy-momentum deposition due to neutrino-antineutrino annihilation in the vicinity of axisymmetric, accreting black holes (BHs) by numerically ray-tracing neutrino trajectories in a Kerr space-time. Hyperaccreting stellar-mass BHs are widely considered as energy sources that can drive ultrarelativistic outflows with the potential to produce gamma-ray bursts. In contrast to earlier works, we provide an extensive and detailed parameter study of the influence of general relativistic (GR) effects and of different neutrinosphere geometries. These include idealized thin disks, tori, and spheres, or are constructed as non-selfgravitating equilibrium matter distributions for va…
The IceCube prototype string in Amanda
2006
The Antarctic Muon And Neutrino Detector Array (Amanda) is a high-energy neutrino telescope. It is a lattice of optical modules (OM) installed in the clear ice below the South Pole Station. Each OM contains a photomultiplier tube (PMT) that detects photons of Cherenkov light generated in the ice by muons and electrons. IceCube is a cubic-kilometer-sized expansion of Amanda currently being built at the South Pole. In IceCube the PMT signals are digitized already in the optical modules and transmitted to the surface. A prototype string of 41 OMs equipped with this new all-digital technology was deployed in the Amanda array in the year 2000. In this paper we describe the technology and demonst…
Muon track reconstruction and data selection techniques in AMANDA
2004
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 r…
Calibration and survey of AMANDA with the SPASE detectors
2004
We report on the analysis of air showers observed in coincidence by the Antarctic Muon and Neutrino detector array (AMANDA-B10) and the South Pole Air Shower Experiment (SPASE-1 and SPASE-2). We discuss the use of coincident events for calibration and survey of the deep AMANDA detector as well as the response of AMANDA to muon bundles. This analysis uses data taken during 1997 when both SPASE-1 and SPASE-2 were in operation to provide a stereo view of AMANDA. © 2003 Elsevier B.V. All rights reserved.
The search for Muon neutrinos from northern hemisphere gamma-ray bursts with AMANDA
2007
We present the results of the analysis of neutrino observations by the Antarctic Muon and Neutrino Detector Array (AMANDA) correlated with photon observations of more than 400 gamma-ray bursts (GRBs) in the Northern Hemisphere from 1997 to 2003. During this time period, AMANDA's effective collection area for muon neutrinos was larger than that of any other existing detector. Based on our observations of zero neutrinos during and immediately prior to the GRBs in the dataset, we set the most stringent upper limit on muon neutrino emission correlated with gamma-ray bursts. Assuming a Waxman-Bahcall spectrum and incorporating all systematic uncertainties, our flux upper limit has a normalizatio…
Three-neutrino mixing after the first results from K2K and KamLAND
2003
We analyze the impact of the data on long baseline \nu_\mu disappearance from the K2K experiment and reactor \bar\nu_e disappearance from the KamLAND experiment on the determination of the leptonic three-generation mixing parameters. Performing an up-to-date global analysis of solar, atmospheric, reactor and long baseline neutrino data in the context of three-neutrino oscillations, we determine the presently allowed ranges of masses and mixing and we consistently derive the allowed magnitude of the elements of the leptonic mixing matrix. We also quantify the maximum allowed contribution of \Delta m^2_{21} oscillations to CP-odd and CP-even observables at future long baseline experiments.