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# Träfflista för sökning "WFRF:(Huelsnitz W.) "

Sökning: WFRF:(Huelsnitz W.)

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1.
• Abbasi, R., et al. (författare)
• The IceCube data acquisition system : Signal capture, digitization, and timestamping
• 2009
• Ingår i: Nuclear Instruments and Methods in Physics Research Section A : Accelerators, Spectrometers, Detectors and Associated Equipment. - 0168-9002 .- 1872-9576. ; 601:3, s. 294-316
• Tidskriftsartikel (refereegranskat)abstract
• IceCube is a km-scale neutrino observatory under construction at the South Pole with sensors both in the deep ice (InIce) and on the surface (IceTop). The sensors, called Digital Optical Modules (DOMs). detect, digitize and timestamp the signals from optical Cherenkov-radiation photons. The DOM Main Board (MB) data acquisition subsystem is connected to the central DAQ in the IceCube Laboratory (ICL) by a single twisted copper wire-pair and transmits packetized data on demand. Time calibration is maintained throughout the array by regular transmission to the DOMs of precisely timed analog signals, synchronized to a central GPS-disciplined clock. The design goals and consequent features, functional capabilities, and initial performance of the DOM MB, and the operation of a combined array of DOMs as a system, are described here. Experience with the first InIce strings and the IceTop stations indicates that the system design and performance goals have been achieved. (c) 2009 Elsevier B.V. All rights reserved.
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2.
• Abbasi, R., et al. (författare)
• Search for point sources of high energy neutrinos with final data from AMANDA-II
• 2009
• Ingår i: Physical review D. - 1550-7998. ; 79:6, s. 062001
• Tidskriftsartikel (refereegranskat)abstract
• We present a search for point sources of high energy neutrinos using 3.8 yr of data recorded by AMANDA-II during 2000-2006. After reconstructing muon tracks and applying selection criteria designed to optimally retain neutrino-induced events originating in the northern sky, we arrive at a sample of 6595 candidate events, predominantly from atmospheric neutrinos with primary energy 100 GeV to 8 TeV. Our search of this sample reveals no indications of a neutrino point source. We place the most stringent limits to date on E-2 neutrino fluxes from points in the northern sky, with an average upper limit of E-2 Phi(nu mu)+nu(tau)&lt;= 5.2x10(-11) TeV cm(-2) s(-1) on the sum of nu(mu) and nu(tau) fluxes, assumed equal, over the energy range from 1.9 TeV to 2.5 PeV.
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3.
• Abbasi, R., et al. (författare)
• Determination of the atmospheric neutrino flux and searches for new physics with AMANDA-II
• 2009
• Ingår i: Physical Review D. - 1550-7998. ; 79:10, s. 102005
• Tidskriftsartikel (refereegranskat)abstract
• The AMANDA-II detector, operating since 2000 in the deep ice at the geographic South Pole, has accumulated a large sample of atmospheric muon neutrinos in the 100 GeV to 10 TeV energy range. The zenith angle and energy distribution of these events can be used to search for various phenomenological signatures of quantum gravity in the neutrino sector, such as violation of Lorentz invariance or quantum decoherence. Analyzing a set of 5511 candidate neutrino events collected during 1387 days of livetime from 2000 to 2006, we find no evidence for such effects and set upper limits on violation of Lorentz invariance and quantum decoherence parameters using a maximum likelihood method. Given the absence of evidence for new flavor-changing physics, we use the same methodology to determine the conventional atmospheric muon neutrino flux above 100 GeV.
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4.
• Abbasi, R., et al. (författare)
• Extending the Search for Neutrino Point Sources with IceCube above the Horizon
• 2009
• Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 103:22, s. 221102
• Tidskriftsartikel (refereegranskat)abstract
• Point source searches with the IceCube neutrino telescope have been restricted to one hemisphere, due to the exclusive selection of upward going events as a way of rejecting the atmospheric muon background. We show that the region above the horizon can be included by suppressing the background through energy-sensitive cuts. This improves the sensitivity above PeV energies, previously not accessible for declinations of more than a few degrees below the horizon due to the absorption of neutrinos in Earth. We present results based on data collected with 22 strings of IceCube, extending its field of view and energy reach for point source searches. No significant excess above the atmospheric background is observed in a sky scan and in tests of source candidates. Upper limits are reported, which for the first time cover point sources in the southern sky up to EeV energies.
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5.
• Abbasi, R., et al. (författare)
• Limits on a Muon Flux from Neutralino Annihilations in the Sun with the IceCube 22-String Detector
• 2009
• Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 102:20, s. 201302
• Tidskriftsartikel (refereegranskat)abstract
• A search for muon neutrinos from neutralino annihilations in the Sun has been performed with the IceCube 22-string neutrino detector using data collected in 104.3 days of live time in 2007. No excess over the expected atmospheric background has been observed. Upper limits have been obtained on the annihilation rate of captured neutralinos in the Sun and converted to limits on the weakly interacting massive particle (WIMP) proton cross sections for WIMP masses in the range 250-5000 GeV. These results are the most stringent limits to date on neutralino annihilation in the Sun.
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6.
• Abbasi, R., et al. (författare)
• SEARCH FOR HIGH-ENERGY MUON NEUTRINOS FROM THE "NAKED-EYE" GRB 080319B WITH THE IceCube NEUTRINO TELESCOPE
• 2009
• Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 701:2, s. 1721-1731
• Tidskriftsartikel (refereegranskat)abstract
• We report on a search with the IceCube detector for high-energy muon neutrinos from GRB 080319B, one of the brightest gamma-ray bursts (GRBs) ever observed. The fireball model predicts that a mean of 0.1 events should be detected by IceCube for a bulk Lorentz boost of the jet of 300. In both the direct on-time window of 66 s and an extended window of about 300 s around the GRB, no excess was found above background. The 90% CL upper limit on the number of track-like events from the GRB is 2.7, corresponding to a muon neutrino fluence limit of 9.5 x 10(-3) erg cm(-2) in the energy range between 120 TeV and 2.2 PeV, which contains 90% of the expected events.
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7.
• Abbasi, R., et al. (författare)
• Searching for soft relativistic jets in core-collapse supernovae with the IceCube optical follow-up program
• 2012
• Ingår i: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 539, s. A60
• Tidskriftsartikel (refereegranskat)abstract
• Context. Transient neutrino sources such as gamma-ray bursts (GRBs) and supernovae (SNe) are hypothesized to emit bursts of high-energy neutrinos on a time-scale of less than or similar to 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. Aims. 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. Methods. If a neutrino multiplet, i.e. 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. Results. No statistically significant excess in the rate of neutrino multiplets has been observed and furthermore no coincidence with an optical counterpart was found. Conclusions. The search allows, for the first time, to set stringent limits on current models predicting a high-energy neutrino flux from soft relativistic hadronic jets in core-collapse SNe. We conclude that a sub-population of SNe with typical Lorentz boost factor and jet energy of 10 and 3 x 1051 erg, respectively, does not exceed 4.2% at 90% confidence.
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8.
• Abbasi, R., et al. (författare)
• All-particle cosmic ray energy spectrum measured with 26 IceTop stations
• 2013
• Ingår i: Astroparticle physics. - 0927-6505 .- 1873-2852. ; 44, s. 40-58
• Tidskriftsartikel (refereegranskat)abstract
• We report on a measurement of the cosmic ray energy spectrum with the IceTop air shower array, the surface component of the IceCube Neutrino Observatory at the South Pole. The data used in this analysis were taken between June and October, 2007, with 26 surface stations operational at that time, corresponding to about one third of the final array. The fiducial area used in this analysis was 0.122 km(2). The analysis investigated the energy spectrum from 1 to 100 PeV measured for three different zenith angle ranges between 0 degrees and 46 degrees. Because of the isotropy of cosmic rays in this energy range the spectra from all zenith angle intervals have to agree. The cosmic-ray energy spectrum was determined under different assumptions on the primary mass composition. Good agreement of spectra in the three zenith angle ranges was found for the assumption of pure proton and a simple two-component model. For zenith angles theta &lt; 30 degrees, where the mass dependence is smallest, the knee in the cosmic ray energy spectrum was observed at about 4 PeV, with a spectral index above the knee of about -3.1. Moreover, an indication of a flattening of the spectrum above 22 PeV was observed.
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9.
• Abbasi, R., et al. (författare)
• An absence of neutrinos associated with cosmic-ray acceleration in gamma-ray bursts
• 2012
• Ingår i: Nature. - 0028-0836 .- 1476-4687. ; 484:7394, s. 351-354
• Tidskriftsartikel (refereegranskat)abstract
• Very energetic astrophysical events are required to accelerate cosmic rays to above 10(18) electronvolts. GRBs (c-ray bursts) have been proposed as possible candidate sources(1-3). In the GRB 'fireball' model, cosmic-ray acceleration should be accompanied by neutrinos produced in the decay of charged pions created in interactions between the high-energy cosmic-ray protons and gamma-rays(4). Previous searches for such neutrinos found none, but the constraints were weak because the sensitivity was at best approximately equal to the predicted flux(5-7). Here we report an upper limit on the flux of energetic neutrinos associated with GRBs that is at least a factor of 3.7 below the predictions(4,8-10). This implies either that GRBs are not the only sources of cosmic rays with energies exceeding 10(18) electronvolts or that the efficiency of neutrino production is much lower than has been predicted.
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10.
• Abbasi, R., et al. (författare)
• First Neutrino Point-Source Results from the 22 String Icecube Detector
• 2009
• Ingår i: The Astrophysical Journal Letters. - 2041-8205. ; 701:1, s. L47-L51
• Tidskriftsartikel (refereegranskat)abstract
• We present new results of searches for neutrino point sources in the northern sky, using data recorded in 2007-2008 with 22 strings of the IceCube detector (approximately one-fourth of the planned total) and 275.7 days of live time. The final sample of 5114 neutrino candidate events agrees well with the expected background of atmospheric muon neutrinos and a small component of atmospheric muons. No evidence of a point source is found, with the most significant excess of events in the sky at 2.2Ïƒ after accounting for all trials. The average upper limit over the northern sky for point sources of muon-neutrinos with E â€“2 spectrum is ##IMG## [http://ej.iop.org/images/1538-4357/701/1/L47/apjl318527ieqn1.gif] $E^2\,Φ _ν _μ &lt; 1.4 \,\,\times\,\, 10^-11\; \mathrmTeV\;cm^-2\;\mathrms^-1$ , in the energy range from 3Â TeV to 3Â PeV, improving the previous best average upper limit by the AMANDA-II detector by a factor of 2.
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