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Sökning: WFRF:(Karg Matthias)

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1.
  • Abbasi, Rasha, et al. (författare)
  • IceCube search for neutrinos from GRB 221009A
  • 2023
  • Ingår i: Proceedings of 38th International Cosmic Ray Conference (ICRC 2023). - : Sissa Medialab Srl.
  • Konferensbidrag (refereegranskat)abstract
    •  GRB 221009A is the brightest Gamma Ray Burst (GRB) ever observed. The observed extremelyhigh flux of high and very-high-energy photons provide a unique opportunity to probe the predictedneutrino counterpart to the electromagnetic emission. We have used a variety of methods to searchfor neutrinos in coincidence with the GRB over several time windows during the precursor, promptand afterglow phases of the GRB. MeV scale neutrinos are studied using photo-multiplier ratescalers which are normally used to search for galactic core-collapse supernovae neutrinos. GeVneutrinos are searched starting with DeepCore triggers. These events don’t have directionallocalization, but instead can indicate an excess in the rate of events. 10 GeV - 1 TeV and >TeVneutrinos are searched using traditional neutrino point source methods which take into accountthe direction and time of events with DeepCore and the entire IceCube detector respectively. The>TeV results include both a fast-response analysis conducted by IceCube in real-time with timewindows of T0 − 1 to T0 + 2 hours and T0 ± 1 day around the time of GRB 221009A, as well asan offline analysis with 3 new time windows up to a time window of T0 − 1 to T0 + 14 days, thelongest time period we consider. The combination of observations by IceCube covers 9 ordersof magnitude in neutrino energy, from MeV to PeV, placing upper limits across the range forpredicted neutrino emission.
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2.
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3.
  • Aartsen, M. G., et al. (författare)
  • Atmospheric and astrophysical neutrinos above 1 TeV interacting in IceCube
  • 2015
  • Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 91:2, s. 022001-
  • Tidskriftsartikel (refereegranskat)abstract
    • The IceCube Neutrino Observatory was designed primarily to search for high-energy (TeV-PeV) neutLrinos produced in distant astrophysical objects. A search for. greater than or similar to 100 TeV neutrinos interacting inside the instrumented volume has recently provided evidence for an isotropic flux of such neutrinos. At lower energies, IceCube collects large numbers of neutrinos from the weak decays of mesons in cosmic-ray air showers. Here we present the results of a search for neutrino interactions inside IceCube's instrumented volume between 1 TeV and 1 PeV in 641 days of data taken from 2010-2012, lowering the energy threshold for neutrinos from the southern sky below 10 TeV for the first time, far below the threshold of the previous high-energy analysis. Astrophysical neutrinos remain the dominant component in the southern sky down to a deposited energy of 10 TeV. From these data we derive new constraints on the diffuse astrophysical neutrino spectrum, Phi(v) = 2.06(-0.3)(+0.4) x 10(-18) (E-v = 10(5) GeV)-2.46 +/- 0.12GeV-1 cm(-2) sr(-1) s(-1) for 25 TeV < E-v < 1.4 PeV, as well as the strongest upper limit yet on the flux of neutrinos from charmed-meson decay in the atmosphere, 1.52 times the benchmark theoretical prediction used in previous IceCube results at 90% confidence.
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4.
  • Aartsen, M. G., et al. (författare)
  • Development of a general analysis and unfolding scheme and its application to measure the energy spectrum of atmospheric neutrinos with IceCube
  • 2015
  • Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 75:3
  • Tidskriftsartikel (refereegranskat)abstract
    • We present the development and application of a generic analysis scheme for the measurement of neutrino spectra with the IceCube detector. This scheme is based on regularized unfolding, preceded by an event selection which uses a Minimum Redundancy Maximum Relevance algorithm to select the relevant variables and a random forest for the classification of events. The analysis has been developed using IceCube data from the 59-string configuration of the detector. 27,771 neutrino candidates were detected in 346 days of livetime. A rejection of 99.9999 % of the atmospheric muon background is achieved. The energy spectrum of the atmospheric neutrino flux is obtained using the TRUEE unfolding program. The unfolded spectrum of atmospheric muon neutrinos covers an energy range from 100 GeV to 1 PeV. Compared to the previous measurement using the detector in the 40-string configuration, the analysis presented here, extends the upper end of the atmospheric neutrino spectrum by more than a factor of two, reaching an energy region that has not been previously accessed by spectral measurements.
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5.
  • Aartsen, M. G., et al. (författare)
  • Energy reconstruction methods in the IceCube neutrino telescope
  • 2014
  • Ingår i: Journal of Instrumentation. - 1748-0221. ; 9, s. P03009-
  • Tidskriftsartikel (refereegranskat)abstract
    • Accurate measurement of neutrino energies is essential to many of the scientific goals of large-volume neutrino telescopes. The fundamental observable in such detectors is the Cherenkov light produced by the transit through a medium of charged particles created in neutrino interactions. The amount of light emitted is proportional to the deposited energy, which is approximately equal to the neutrino energy for v(e) and v(mu) charged-current interactions and can be used to set a lower bound on neutrino energies and to measure neutrino spectra statistically in other channels. Here we describe methods and performance of reconstructing charged-particle energies and topologies from the observed Cherenkov light yield, including techniques to measure the energies of uncontained muon tracks, achieving average uncertainties in electromagnetic-equivalent deposited energy of similar to 15% above 10 TeV.
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6.
  • Aartsen, M. G., et al. (författare)
  • Evidence for High-Energy Extraterrestrial Neutrinos at the IceCube Detector
  • 2013
  • Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 342:6161, s. 947-
  • Tidskriftsartikel (refereegranskat)abstract
    • We report on results of an all-sky search for high-energy neutrino events interacting within the IceCube neutrino detector conducted between May 2010 and May 2012. The search follows up on the previous detection of two PeV neutrino events, with improved sensitivity and extended energy coverage down to about 30 TeV. Twenty-six additional events were observed, substantially more than expected from atmospheric backgrounds. Combined, both searches reject a purely atmospheric origin for the 28 events at the 4 sigma level. These 28 events, which include the highest energy neutrinos ever observed, have flavors, directions, and energies inconsistent with those expected from the atmospheric muon and neutrino backgrounds. These properties are, however, consistent with generic predictions for an additional component of extraterrestrial origin.
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7.
  • Aartsen, M. G., et al. (författare)
  • First Observation of PeV-Energy Neutrinos with IceCube
  • 2013
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 111:2, s. 021103-
  • Tidskriftsartikel (refereegranskat)abstract
    • We report on the observation of two neutrino-induced events which have an estimated deposited energy in the IceCube detector of 1.04 +/- 0.16 and 1.14 +/- 0.17 PeV, respectively, the highest neutrino energies observed so far. These events are consistent with fully contained particle showers induced by neutral-current nu(e,mu,tau) ((nu) over bar (e,mu,tau)) or charged-current nu(e) ((nu) over bar (e)) interactions within the IceCube detector. The events were discovered in a search for ultrahigh energy neutrinos using data corresponding to 615.9 days effective live time. The expected number of atmospheric background is 0.082 +/- 0.004(stat)(-0.057)(+0.041)(syst). The probability of observing two or more candidate events under the atmospheric background-only hypothesis is 2.9 x 10(-3) (2.8 sigma) taking into account the uncertainty on the expected number of background events. These two events could be a first indication of an astrophysical neutrino flux; the moderate significance, however, does not permit a definitive conclusion at this time.
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8.
  • Aartsen, M. G., et al. (författare)
  • IceCube search for dark matter annihilation in nearby galaxies and galaxy clusters
  • 2013
  • Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 88:12
  • Tidskriftsartikel (refereegranskat)abstract
    • We present the results of a first search for self-annihilating dark matter in nearby galaxies and galaxy clusters using a sample of high-energy neutrinos acquired in 339.8 days of live time during 2009/10 with the IceCube neutrino observatory in its 59-string configuration. The targets of interest include the Virgo and Coma galaxy clusters, the Andromeda galaxy, and several dwarf galaxies. We obtain upper limits on the cross section as a function of the weakly interacting massive particle mass between 300 GeV and 100 TeV for the annihilation into b (b) over bar, W+(W) over bar (-), tau(+)tau(-), mu(+)mu(-) , and nu(nu) over bar. A limit derived for the Virgo cluster, when assuming a large effect from subhalos, challenges the weakly interacting massive particle interpretation of a recently observed GeV positron excess in cosmic rays.
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9.
  • Aartsen, M. G., et al. (författare)
  • Improved limits on dark matter annihilation in the Sun with the 79-string IceCube detector and implications for supersymmetry
  • 2016
  • Ingår i: Journal of Cosmology and Astroparticle Physics. - : IOP Publishing. - 1475-7516. ; :4
  • Tidskriftsartikel (refereegranskat)abstract
    • We present an improved event-level likelihood formalism for including neutrino telescope data in global fits to new physics. We derive limits on spin-dependent dark matter-proton scattering by employing the new formalism in a re-analysis of data from the 79-string IceCube search for dark matter annihilation in the Sun, including explicit energy information for each event. The new analysis excludes a number of models in the weak-scale minimal supersymmetric standard model (MSSM) for the first time. This work is accompanied by the public release of the 79-string IceCube data, as well as an associated computer code for applying the new likelihood to arbitrary dark matter models.
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10.
  • Aartsen, M. G., et al. (författare)
  • Improvement in fast particle track reconstruction with robust statistics
  • 2014
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 736, s. 143-149
  • Tidskriftsartikel (refereegranskat)abstract
    • The IceCube project has transformed 1 km(3) of deep natural Antarctic ice into a Cherenkov detector Muon neutrinos are detected and their direction is inferred by mapping the light produced by the secondary muon track inside the volume instrumented with photomultipliers. Reconstructing the muon track from the observed light is challenging due to noise, light scattering in the ice medium, and the possibility of simultaneously having multiple muons inside the detector, resulting from the large flux of cosmic ray muons. This paper describes work on two problems: (1) the truck reconstruction problem, in which, given a set of observations, the goal is to recover the track of a muon; and (2) the coincident event problem, which is to determine how many muons are active in the detector during a time window. Rather than solving these problems by developing more complex physical models that are applied at later stages of the analysis, our approach is to augment the detector's early reconstruction with data filters and robust statistical techniques. These can be implemented at the level of on-line reconstruction and, therefore, improve all subsequent reconstructions. Using the metric of median angular resolution, a standard metric for track reconstruction, we improve the accuracy in the initial reconstruction direction by 13%. We also present improvements in measuring the number of muons in coincident events: we can accurately determine the number of muons 98% of the time.
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11.
  • Aartsen, M. G., et al. (författare)
  • Measurement of Atmospheric Neutrino Oscillations with IceCube
  • 2013
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 111:8, s. 081801-
  • Tidskriftsartikel (refereegranskat)abstract
    • We present the first statistically significant detection of neutrino oscillations in the high-energy regime (> 20 GeV) from an analysis of IceCube Neutrino Observatory data collected in 2010 and 2011. This measurement is made possible by the low-energy threshold of the DeepCore detector (similar to 20 GeV) and benefits from the use of the IceCube detector as a veto against cosmic-ray-induced muon background. The oscillation signal was detected within a low-energy muon neutrino sample (20-100 GeV) extracted from data collected by DeepCore. A high-energy muon neutrino sample (100 GeV-10 TeV) was extracted from IceCube data to constrain systematic uncertainties. The disappearance of low-energy upward-going muon neutrinos was observed, and the nonoscillation hypothesis is rejected with more than 5 sigma significance. In a two-neutrino flavor formalism, our data are best described by the atmospheric neutrino oscillation parameters vertical bar Delta m(32)(2)vertical bar = (2.3(-0.5)(+0.6)) x 10(-3) eV(2) and sin(2) (2 theta(23)) > 0.93, and maximum mixing is favored.
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12.
  • Aartsen, M. G., et al. (författare)
  • Measurement of South Pole ice transparency with the IceCube LED calibration system
  • 2013
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 711, s. 73-89
  • Tidskriftsartikel (refereegranskat)abstract
    • The IceCube Neutrino Observatory, approximately 1 km(3) in size, is now complete with 86 strings deployed in the Antarctic ice. IceCube detects the Cherenkov radiation emitted by charged particles passing through or created in the ice. To realize the full potential of the detector, the properties of light propagation in the ice in and around the detector must be well understood. This report presents a new method of fitting the model of light propagation in the ice to a data set of in situ light source events collected with IceCube. The resulting set of derived parameters, namely the measured values of scattering and absorption coefficients vs. depth, is presented and a comparison of IceCube data with simulations based on the new model is shown.
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13.
  • Aartsen, M. G., et al. (författare)
  • Measurement of the Atmospheric nu(e) Flux in IceCube
  • 2013
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 110:15, s. 151105-
  • Tidskriftsartikel (refereegranskat)abstract
    • We report the first measurement of the atmospheric electron neutrino flux in the energy range between approximately 80 GeV and 6 TeV, using data recorded during the first year of operation of IceCube's DeepCore low-energy extension. Techniques to identify neutrinos interacting within the DeepCore volume and veto muons originating outside the detector are demonstrated. A sample of 1029 events is observed in 281 days of data, of which 496 +/- 66(stat) +/- 88(syst) are estimated to be cascade events, including both electron neutrino and neutral current events. The rest of the sample includes residual backgrounds due to atmospheric muons and charged current interactions of atmospheric muon neutrinos. The flux of the atmospheric electron neutrinos is consistent with models of atmospheric neutrinos in this energy range. This constitutes the first observation of electron neutrinos and neutral current interactions in a very large volume neutrino telescope optimized for the TeV energy range.
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14.
  • Aartsen, M. G., et al. (författare)
  • Measurement of the cosmic ray energy spectrum with IceTop-73
  • 2013
  • Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 88:4, s. 042004-
  • Tidskriftsartikel (refereegranskat)abstract
    • We report on the measurement of the all-particle cosmic ray energy spectrum with the IceTop air shower array in the energy range from 1.58 PeV to 1.26 EeV. The IceTop air shower array is the surface component of the IceCube Neutrino Observatory at the geographical South Pole. The analysis was performed using only information from IceTop. The data used in this work were taken from June 1, 2010 to May 13, 2011. During that period the IceTop array consisted of 73 stations, compared to 81 in its final configuration. The measured spectrum exhibits a clear deviation from a single power law above the knee around 4 PeV and below 1 EeV. We observe spectral hardening around 18 PeV and steepening around 130 PeV.
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15.
  • Aartsen, M. G., et al. (författare)
  • Multipole analysis of IceCube data to search for dark matter accumulated in the Galactic halo
  • 2015
  • Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 75:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Dark matter which is bound in the Galactic halo might self-annihilate and produce a flux of stable final state particles, e. g. high energy neutrinos. These neutrinos can be detected with IceCube, a cubic-kilometer sized Cherenkov detector. Given IceCube's large field of view, a characteristic anisotropy of the additional neutrino flux is expected. In this paper we describe a multipole method to search for such a large-scale anisotropy in IceCube data. This method uses the expansion coefficients of a multipole expansion of neutrino arrival directions and incorporates signal-specific weights for each expansion coefficient. We apply the technique to a high-purity muon neutrino sample from the Northern Hemisphere. The final result is compatible with the null-hypothesis. As no signal was observed, we present limits on the self-annihilation cross-section averaged over the relative velocity distribution down to 1.9x10(-23) cm(3) s(-1) for a dark matter particle mass of 700-1,000 GeV and direct annihilation into nu(nu) over bar. The resulting exclusion limits come close to exclusion limits from gamma-ray experiments, that focus on the outer Galactic halo, for high dark matter masses of a few TeV and hard annihilation channels.
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16.
  • Aartsen, M. G., et al. (författare)
  • Observation of Cosmic-Ray Anisotropy with the Icetop Air Shower Array
  • 2013
  • Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 765:1, s. 55-
  • Tidskriftsartikel (refereegranskat)abstract
    • We report on the observation of anisotropy in the arrival direction distribution of cosmic rays at PeV energies. The analysis is based on data taken between 2009 and 2012 with the IceTop air shower array at the south pole. IceTop, an integral part of the IceCube detector, is sensitive to cosmic rays between 100 TeV and 1 EeV. With the current size of the IceTop data set, searches for anisotropy at the 10(-3) level can, for the first time, be extended to PeV energies. We divide the data set into two parts with median energies of 400 TeV and 2 PeV, respectively. In the low energy band, we observe a strong deficit with an angular size of about 30 degrees and an amplitude of (-1.58 +/- 0.46(stat) +/- 0.52(sys)) x 10(-3) at a location consistent with previous observations of cosmic rays with the IceCube neutrino detector. The study of the high energy band shows that the anisotropy persists to PeV energies and increases in amplitude to (-3.11 +/- 0.38(stat) +/- 0.96(sys)) x 10(-3).
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17.
  • Aartsen, M. G., et al. (författare)
  • Observation of High-Energy Astrophysical Neutrinos in Three Years of IceCube Data
  • 2014
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 113:10, s. 101101-
  • Tidskriftsartikel (refereegranskat)abstract
    • A search for high-energy neutrinos interacting within the IceCube detector between 2010 and 2012 provided the first evidence for a high-energy neutrino flux of extraterrestrial origin. Results from an analysis using the same methods with a third year (2012-2013) of data from the complete IceCube detector are consistent with the previously reported astrophysical flux in the 100 TeV-PeV range at the level of 10(-8) GeV cm(-2) s(-1) sr(-1) per flavor and reject a purely atmospheric explanation for the combined three-year data at 5.7 sigma. The data are consistent with expectations for equal fluxes of all three neutrino flavors and with isotropic arrival directions, suggesting either numerous or spatially extended sources. The three-year data set, with a live time of 988 days, contains a total of 37 neutrino candidate events with deposited energies ranging from 30 to 2000 TeV. The 2000-TeV event is the highest-energy neutrino interaction ever observed.
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18.
  • Aartsen, M. G., et al. (författare)
  • Observation of the cosmic-ray shadow of the Moon with IceCube
  • 2014
  • Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 89:10, s. 102004-
  • Tidskriftsartikel (refereegranskat)abstract
    • We report on the observation of a significant deficit of cosmic rays from the direction of the Moon with the IceCube detector. The study of this "Moon shadow" is used to characterize the angular resolution and absolute pointing capabilities of the detector. The detection is based on data taken in two periods before the completion of the detector: between April 2008 and May 2009, when IceCube operated in a partial configuration with 40 detector strings deployed in the South Pole ice, and between May 2009 and May 2010 when the detector operated with 59 strings. Using two independent analysis methods, the Moon shadow has been observed to high significance (> 6 sigma) in both detector configurations. The observed location of the shadow center is within 0.2 degrees of its expected position when geomagnetic deflection effects are taken into account. This measurement validates the directional reconstruction capabilities of IceCube.
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19.
  • Aartsen, M. G., et al. (författare)
  • Probing the origin of cosmic rays with extremely high energy neutrinos using the IceCube Observatory
  • 2013
  • Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 88:11
  • Tidskriftsartikel (refereegranskat)abstract
    • We have searched for extremely high energy neutrinos using data taken with the IceCube detector between May 2010 and May 2012. Two neutrino-induced particle shower events with energies around 1 PeV were observed, as reported previously. In this work, we investigate whether these events could originate from cosmogenic neutrinos produced in the interactions of ultrahigh energy cosmic rays with ambient photons while propagating through intergalactic space. Exploiting IceCube's large exposure for extremely high energy neutrinos and the lack of observed events above 100 PeV, we can rule out the corresponding models at more than 90% confidence level. The model-independent quasidifferential 90% C. L. upper limit, which amounts to E-2 phi(nu e)+(nu mu)+(nu tau) = 1.2 x 10(-7) GeV cm(-2) s(-1) sr(-1) at 1 EeV, provides the most stringent constraint in the energy range from 10 PeV to 10 EeV. Our observation disfavors strong cosmological evolution of the highest energy cosmic-ray sources such as the Fanaroff-Riley type II class of radio galaxies.
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20.
  • Aartsen, M. G., et al. (författare)
  • Search for a diffuse flux of astrophysical muon neutrinos with the IceCube 59-string configuration
  • 2014
  • Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 89:6, s. 062007-
  • Tidskriftsartikel (refereegranskat)abstract
    • A search for high-energy neutrinos was performed using data collected by the IceCube Neutrino Observatory from May 2009 to May 2010, when the array was running in its 59-string configuration. The data sample was optimized to contain muon neutrino induced events with a background contamination of atmospheric muons of less than 1%. These data, which are dominated by atmospheric neutrinos, are analyzed with a global likelihood fit to search for possible contributions of prompt atmospheric and astrophysical neutrinos, neither of which have yet been identified. Such signals are expected to follow a harder energy spectrum than conventional atmospheric neutrinos. In addition, the zenith angle distribution differs for astrophysical and atmospheric signals. A global fit of the reconstructed energies and directions of observed events is performed, including possible neutrino flux contributions for an astrophysical signal and atmospheric backgrounds as well as systematic uncertainties of the experiment and theoretical predictions. The best fit yields an astrophysical signal flux for nu(mu) + (nu) over bar (mu) of E-2. Phi(E) = 0.25 x 10(-8) GeV cm(-2) s(-1) sr(-1), and a zero prompt component. Although the sensitivity of this analysis for astrophysical neutrinos surpasses the Waxman and Bahcall upper bound, the experimental limit at 90% confidence level is a factor of 1.5 above at a flux of E-2 . Phi(E) = 1.44 x 10(-8) GeV cm(-2) s(-1) sr(-1).
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21.
  • Aartsen, M. G., et al. (författare)
  • Search for Dark Matter Annihilations in the Sun with the 79-String IceCube Detector
  • 2013
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 110:13, s. 131302-
  • Tidskriftsartikel (refereegranskat)abstract
    • We have performed a search for muon neutrinos from dark matter annihilation in the center of the Sun with the 79-string configuration of the IceCube neutrino telescope. For the first time, the DeepCore subarray is included in the analysis, lowering the energy threshold and extending the search to the austral summer. The 317 days of data collected between June 2010 and May 2011 are consistent with the expected background from atmospheric muons and neutrinos. Upper limits are set on the dark matter annihilation rate, with conversions to limits on spin-dependent and spin-independent scattering cross sections of weakly interacting massive particles (WIMPs) on protons, for WIMP masses in the range 20-5000 GeV=c(2). These are the most stringent spin-dependent WIMP-proton cross section limits to date above 35 GeV=c(2) for most WIMP models. 
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22.
  • Aartsen, M. G., et al. (författare)
  • Search for Galactic PeV gamma rays with the IceCube Neutrino Observatory
  • 2013
  • Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 87:6, s. 062002-
  • Tidskriftsartikel (refereegranskat)abstract
    • Gamma-ray induced air showers are notable for their lack of muons, compared to hadronic showers. Hence, air shower arrays with large underground muon detectors can select a sample greatly enriched in photon showers by rejecting showers containing muons. IceCube is sensitive to muons with energies above similar to 500 GeV at the surface, which provides an efficient veto system for hadronic air showers with energies above 1 PeV. One year of data from the 40-string IceCube configuration was used to perform a search for point sources and a Galactic diffuse signal. No sources were found, resulting in a 90% C.L. upper limit on the ratio of gamma rays to cosmic rays of 1.2 x 10(-3) for the flux coming from the Galactic plane region (-80 degrees less than or similar to l less than or similar to -30 degrees; -10 degrees less than or similar to b less than or similar to 5 degrees) in the energy range 1.2-6.0 PeV. In the same energy range, point source fluxes with E-2 spectra have been excluded at a level of (E/TeV)(2)d Phi/dE similar to 10(-12)-10(-11) cm(-2) s(-1) TeV-1 depending on source declination. The complete IceCube detector will have a better sensitivity (due to the larger detector size), improved reconstruction, and vetoing techniques. Preliminary data from the nearly final IceCube detector configuration have been used to estimate the 5-yr sensitivity of the full detector. It is found to be more than an order of magnitude better, allowing the search for PeV extensions of known TeV gamma-ray emitters.
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23.
  • Aartsen, M. G., et al. (författare)
  • Search for neutrino-induced particle showers with IceCube-40
  • 2014
  • Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 89:10, s. 102001-
  • Tidskriftsartikel (refereegranskat)abstract
    • We report on the search for neutrino-induced particle showers, so-called cascades, in the IceCube-40 detector. The data for this search were collected between April 2008 and May 2009 when the first 40 IceCube strings were deployed and operational. Three complementary searches were performed, each optimized for different energy regimes. The analysis with the lowest energy threshold (2 TeV) targeted atmospheric neutrinos. A total of 67 events were found, consistent with the expectation of 41 atmospheric muons and 30 atmospheric neutrino events. The two other analyses targeted a harder, astrophysical neutrino flux. The analysis with an intermediate threshold of 25 TeV leads to the observation of 14 cascadelike events, again consistent with the prediction of 3.0 atmospheric neutrino and 7.7 atmospheric muon events. We hence set an upper limit of E-2 Phi(lim) <= 7.46 x 10(-8) GeV sr(-1) s(-1) cm(-2) (90% C.L.) on the diffuse flux from astrophysical neutrinos of all neutrino flavors, applicable to the energy range 25 TeV to 5 PeV, assuming an E-nu(-2) spectrum and a neutrino flavor ratio of 1: 1: 1 at the Earth. The third analysis utilized a larger and optimized sample of atmospheric muon background simulation, leading to a higher energy threshold of 100 TeV. Three events were found over a background prediction of 0.04 atmospheric muon events and 0.21 events from the flux of conventional and prompt atmospheric neutrinos. Including systematic errors this corresponds to a 2.7 sigma excess with respect to the background-only hypothesis. Our observation of neutrino event candidates above 100 TeV complements IceCube's recently observed evidence for high-energy astrophysical neutrinos.
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24.
  • Aartsen, M. G., et al. (författare)
  • Search for non-relativistic magnetic monopoles with IceCube
  • 2014
  • Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 74:7, s. 2938-
  • Tidskriftsartikel (refereegranskat)abstract
    • The IceCube Neutrino Observatory is a large Cherenkov detector instrumenting of Antarctic ice. The detector can be used to search for signatures of particle physics beyond the Standard Model. Here, we describe the search for non-relativistic, magnetic monopoles as remnants of the Grand Unified Theory (GUT) era shortly after the Big Bang. Depending on the underlying gauge group these monopoles may catalyze the decay of nucleons via the Rubakov-Callan effect with a cross section suggested to be in the range of to . In IceCube, the Cherenkov light from nucleon decays along the monopole trajectory would produce a characteristic hit pattern. This paper presents the results of an analysis of first data taken from May 2011 until May 2012 with a dedicated slow-particle trigger for DeepCore, a subdetector of IceCube. A second analysis provides better sensitivity for the brightest non-relativistic monopoles using data taken from May 2009 until May 2010. In both analyses no monopole signal was observed. For catalysis cross sections of the flux of non-relativistic GUT monopoles is constrained up to a level of at a 90 % confidence level, which is three orders of magnitude below the Parker bound. The limits assume a dominant decay of the proton into a positron and a neutral pion. These results improve the current best experimental limits by one to two orders of magnitude, for a wide range of assumed speeds and catalysis cross sections.
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25.
  • Aartsen, M. G., et al. (författare)
  • SEARCHES FOR EXTENDED AND POINT-LIKE NEUTRINO SOURCES WITH FOUR YEARS OF ICECUBE DATA
  • 2014
  • Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 796:2, s. 109-
  • Tidskriftsartikel (refereegranskat)abstract
    • We present results on searches for point-like sources of neutrinos using four years of IceCube data, including the first year of data from the completed 86 string detector. The total livetime of the combined data set is 1373 days. For an E-2 spectrum, the observed 90% C. L. flux upper limits are similar to 10(-12) TeV-1 cm(-2) s(-1) for energies between 1 TeV and 1 PeV in the northern sky and similar to 10(-11) TeV-1 cm(-2) s(-1) for energies between 100 TeV and 100 PeV in the southern sky. This represents a 40% improvement compared to previous publications, resulting from both the additional year of data and the introduction of improved reconstructions. In addition, we present the first results from an all-sky search for extended sources of neutrinos. We update the results of searches for neutrino emission from stacked catalogs of sources and test five new catalogs; two of Galactic supernova remnants and three of active galactic nuclei. In all cases, the data are compatible with the background-only hypothesis, and upper limits on the flux of muon neutrinos are reported for the sources considered.
  •  
26.
  • Aartsen, M. G., et al. (författare)
  • Searches for small-scale anisotropies from neutrino point sources with three years of IceCube data
  • 2015
  • Ingår i: Astroparticle physics. - : Elsevier BV. - 0927-6505 .- 1873-2852. ; 66, s. 39-52
  • Tidskriftsartikel (refereegranskat)abstract
    • Recently, IceCube found evidence for a diffuse signal of astrophysical neutrinos in an energy range of similar to 60 TeV to the PeV-scale [1]. The origin of those events, being a key to understanding the origin of cosmic rays, is still an unsolved question. So far, analyses have not succeeded to resolve the diffuse signal into point-like sources. Searches including a maximum-likelihood-ratio test, based on the reconstructed directions and energies of the detected down- and up-going neutrino candidates, were also performed on IceCube data leading to the exclusion of bright point sources. In this paper, we present two methods to search for faint neutrino point sources in three years of IceCube data, taken between 2008 and 2011. The first method is an autocorrelation test, applied separately to the northern and southern sky. The second method is a multipole analysis, which expands the measured data in the northern hemisphere into spherical harmonics and uses the resulting expansion coefficients to separate signal from background. With both methods, the results are consistent with the background expectation with a slightly more sparse spatial distribution, corresponding to an underfluctuation. Depending on the assumed number of sources, the resulting upper limit on the flux per source in the northern hemisphere for an E-2 energy spectrum ranges from similar to 1.5. 10(-8) GeV/cm(2) s(-1), in the case of one assumed source, to similar to 4. 10(-10) GeV/cm(2) s(-1), in the case of 3500 assumed sources.
  •  
27.
  • Aartsen, M. G., et al. (författare)
  • South Pole glacial climate reconstruction from multi-borehole laser particulate stratigraphy
  • 2013
  • Ingår i: Journal of Glaciology. - 0022-1430 .- 1727-5652. ; 59:218, s. 1117-1128
  • Tidskriftsartikel (refereegranskat)abstract
    • The IceCube Neutrino Observatory and its prototype, AMANDA, were built in South Pole ice, using powerful hot-water drills to cleanly bore >100 holes to depths up to 2500 m. The construction of these particle physics detectors provided a unique opportunity to examine the deep ice sheet using a variety of novel techniques. We made high-resolution particulate profiles with a laser dust logger in eight of the boreholes during detector commissioning between 2004 and 2010. The South Pole laser logs are among the most clearly resolved measurements of Antarctic dust strata during the last glacial period and can be used to reconstruct paleoclimate records in exceptional detail. Here we use manual and algorithmic matching to synthesize our South Pole measurements with ice-core and logging data from Dome C, East Antarctica. We derive impurity concentration, precision chronology, annual-layer thickness, local spatial variability, and identify several widespread volcanic ash depositions useful for dating. We also examine the interval around similar to 74 ka recently isolated with radiometric dating to bracket the Toba (Sumatra) supereruption.
  •  
28.
  • Aartsen, M. G., et al. (författare)
  • The IceProd framework : Distributed data processing for the IceCube neutrino observatory
  • 2015
  • Ingår i: Journal of Parallel and Distributed Computing. - : Elsevier BV. - 0743-7315 .- 1096-0848. ; 75, s. 198-211
  • Tidskriftsartikel (refereegranskat)abstract
    • IceCube is a one-gigaton instrument located at the geographic South Pole, designed to detect cosmic neutrinos, identify the particle nature of dark matter, and study high-energy neutrinos themselves. Simulation of the IceCube detector and processing of data require a significant amount of computational resources. This paper presents the first detailed description of IceProd, a lightweight distributed management system designed to meet these requirements. It is driven by a central database in order to manage mass production of simulations and analysis of data produced by the IceCube detector. IceProd runs as a separate layer on top of other middleware and can take advantage of a variety of computing resources, including grids and batch systems such as CREAM, HTCondor, and PBS. This is accomplished by a set of dedicated daemons that process job submission in a coordinated fashion through the use of middleware plugins that serve to abstract the details of job submission and job management from the framework. (C) 2014 Elsevier Inc. All rights reserved.
  •  
29.
  • Abbasi, R., et al. (författare)
  • All-particle cosmic ray energy spectrum measured with 26 IceTop stations
  • 2013
  • Ingår i: Astroparticle physics. - : Elsevier BV. - 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 < 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. 
  •  
30.
  • Abbasi, R., et al. (författare)
  • An absence of neutrinos associated with cosmic-ray acceleration in gamma-ray bursts
  • 2012
  • Ingår i: Nature. - : Springer Science and Business Media LLC. - 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.
  •  
31.
  • Abbasi, R., et al. (författare)
  • An improved method for measuring muon energy using the truncated mean of dE/dx
  • 2013
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 703, s. 190-198
  • Tidskriftsartikel (refereegranskat)abstract
    • The measurement of muon energy is critical for many analyses in large Cherenkov detectors, particularly those that involve separating extraterrestrial neutrinos from the atmospheric neutrino background. Muon energy has traditionally been determined by measuring the specific energy loss (dE/dx) along the muon's path and relating the dE/dx to the muon energy. Because high-energy muons (Eμ>1TeV) lose energy randomly, the spread in dE/dx values is quite large, leading to a typical energy resolution of 0.29 in log10(Eμ) for a muon observed over a 1 km path length in the IceCube detector. In this paper, we present an improved method that uses a truncated mean and other techniques to determine the muon energy. The muon track is divided into separate segments with individual dE/dx values. The elimination of segments with the highest dE/dx results in an overall dE/dx that is more closely correlated to the muon energy. This method results in an energy resolution of 0.22 in log10(Eμ), which gives a 26% improvement. This technique is applicable to any large water or ice detector and potentially to large scintillator or liquid argon detectors.
  •  
32.
  • Abbasi, R., et al. (författare)
  • Background studies for acoustic neutrino detection at the South Pole
  • 2012
  • Ingår i: Astroparticle physics. - : Elsevier BV. - 0927-6505 .- 1873-2852. ; 35:6, s. 312-324
  • Tidskriftsartikel (refereegranskat)abstract
    • The detection of acoustic signals from ultra-high energy neutrino interactions is a promising method to measure the flux of cosmogenic neutrinos expected on Earth. The energy threshold for this process depends strongly on the absolute noise level in the target material. The South Pole Acoustic Test Setup (SPATS), deployed in the upper part of four boreholes of the IceCube Neutrino Observatory, has monitored the noise in Antarctic ice at the geographic South Pole for more than two years down to 500 m depth. The noise is very stable and Gaussian distributed. Lacking an in situ calibration up to now, laboratory measurements have been used to estimate the absolute noise level in the 10-50 kHz frequency range to be smaller than 20 mPa. Using a threshold trigger, sensors of the South Pole Acoustic Test Setup registered acoustic events in the IceCube detector volume and its vicinity. Acoustic signals from refreezing IceCube holes and from anthropogenic sources have been used to test the localization of acoustic events. An upper limit on the neutrino flux at energies E-v>10(11) GeV is derived from acoustic data taken over eight months. (C) 2011 Elsevier B.V. All rights reserved.
  •  
33.
  • Abbasi, R., et al. (författare)
  • Calibration and characterization of the IceCube photomultiplier tube
  • 2010
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 618:1-3, s. 139-152
  • Tidskriftsartikel (refereegranskat)abstract
    • Over 5000 PMTs are being deployed at the South Pole to compose the IceCube neutrino observatory. Many are placed deep in the ice to detect Cherenkov light emitted by the products of high-energy neutrino interactions, and others are frozen into tanks on the surface to detect particles from atmospheric cosmic ray showers. IceCube is using the 10-in. diameter R7081-02 made by Hamamatsu Photonics. This paper describes the laboratory characterization and calibration of these PMTs before deployment. PMTs were illuminated with pulses ranging from single photons to saturation level. Parameterizations are given for the single photoelectron charge spectrum and the saturation behavior. Time resolution, late pulses and afterpulses are characterized. Because the PMTs are relatively large, the cathode sensitivity uniformity was measured. The absolute photon detection efficiency was calibrated using Rayleigh-scattered photons from a nitrogen laser. Measured characteristics are discussed in the context of their relevance to IceCube event reconstruction and simulation efforts. (C) 2010 Elsevier B.V. All rights reserved.
  •  
34.
  • Abbasi, R., et al. (författare)
  • Constraints on high-energy neutrino emission from SN 2008D
  • 2011
  • Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 527:4, s. A28-
  • Tidskriftsartikel (refereegranskat)abstract
    • SN 2008D, a core collapse supernova at a distance of 27 Mpc, was serendipitously discovered by the Swift satellite through an associated X-ray flash. Core collapse supernovae have been observed in association with long gamma-ray bursts and X-ray flashes and a physical connection is widely assumed. This connection could imply that some core collapse supernovae possess mildly relativistic jets in which high-energy neutrinos are produced through proton-proton collisions. The predicted neutrino spectra would be detectable by Cherenkov neutrino detectors like IceCube. A search for a neutrino signal in temporal and spatial correlation with the observed X-ray flash of SN 2008D was conducted using data taken in 2007-2008 with 22 strings of the IceCube detector. Events were selected based on a boosted decision tree classifier trained with simulated signal and experimental background data. The classifier was optimized to the position and a "soft jet" neutrino spectrum assumed for SN 2008D. Using three search windows placed around the X-ray peak, emission time scales from 100-10 000 s were probed. No events passing the cuts were observed in agreement with the signal expectation of 0.13 events. Upper limits on the muon neutrino flux from core collapse supernovae were derived for different emission time scales and the principal model parameters were constrained. While no meaningful limits can be given in the case of an isotropic neutrino emission, the parameter space for a jetted emission can be constrained. Future analyses with the full 86 string IceCube detector could detect up to similar to 100 events for a core-collapse supernova at 10 Mpc according to the soft jet model.
  •  
35.
  • Abbasi, R., et al. (författare)
  • Constraints on the extremely-high energy cosmic neutrino flux with the IceCube 2008-2009 data
  • 2011
  • Ingår i: Physical Review D - Particles, Fields, Gravitation and Cosmology. - 1550-7998 .- 1550-2368. ; 83:9, s. 092003-
  • Tidskriftsartikel (refereegranskat)abstract
    • We report on a search for extremely-high energy neutrinos with energies greater than 10(6) GeV using the data taken with the IceCube detector at the South Pole. The data was collected between April 2008 and May 2009 with the half-completed IceCube array. The absence of signal candidate events in the sample of 333.5 days of live time significantly improves model-independent limits from previous searches and allows to place a limit on the diffuse flux of cosmic neutrinos with an E-2 spectrum in the energy range 2.0 x 10(6) - 6.3 x 10(9) GeV to a level of E-2 phi <= 3.6 x 10(-8) GeV cm(-2) sec(-1) sr(-1).
  •  
36.
  • Abbasi, R., et al. (författare)
  • Cosmic ray composition and energy spectrum from 1-30 PeV using the 40-string configuration of IceTop and IceCube
  • 2013
  • Ingår i: Astroparticle physics. - : Elsevier BV. - 0927-6505 .- 1873-2852. ; 42, s. 15-32
  • Tidskriftsartikel (refereegranskat)abstract
    • The mass composition of high energy cosmic rays depends on their production, acceleration, and propagation. The study of cosmic ray composition can therefore reveal hints of the origin of these particles. At the South Pole, the IceCube Neutrino Observatory is capable of measuring two components of cosmic ray air showers in coincidence: the electromagnetic component at high altitude (2835 m) using the IceTop surface array, and the muonic component above ∼1 TeV using the IceCube array. This unique detector arrangement provides an opportunity for precision measurements of the cosmic ray energy spectrum and composition in the region of the knee and beyond. We present the results of a neural network analysis technique to study the cosmic ray composition and the energy spectrum from 1 PeV to 30 PeV using data recorded using the 40-string/40-station configuration of the IceCube Neutrino Observatory.
  •  
37.
  • 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.
  •  
38.
  • Abbasi, R, et al. (författare)
  • FIRST NEUTRINO POINT-SOURCE RESULTS FROM THE 22 STRING ICECUBE DETECTOR
  • 2009
  • Ingår i: Astrophysical Journal Letters. - 2041-8205. ; 701, 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 2.2 sigma after accounting for all trials. The average upper limit over the northern sky for point sources of muon-neutrinos with E-2 spectrum is E-2 Phi(v mu) < 1.4 x 10(-11) TeV cm(-2) s(-1), in the energy range from 3 TeV to 3 PeV, improving the previous best average upper limit by the AMANDA-II detector by a factor of 2.
  •  
39.
  • Abbasi, R., et al. (författare)
  • First search for atmospheric and extraterrestrial neutrino-induced cascades with the IceCube detector
  • 2011
  • Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 84:7, s. 072001-
  • Tidskriftsartikel (refereegranskat)abstract
    • We report on the first search for atmospheric and for diffuse astrophysical neutrino-induced showers (cascades) in the IceCube detector using 257 days of data collected in the year 2007-2008 with 22 strings active. A total of 14 events with energies above 16 TeV remained after event selections in the diffuse analysis, with an expected total background contribution of 8.3 +/- 3.6. At 90% confidence we set an upper limit of E(2)Phi(90%CL) < 3.6 x 10(-7) GeV.cm(-2).s(-1).sr(-1) on the diffuse flux of neutrinos of all flavors in the energy range between 24 TeV and 6.6 PeV assuming that Phi proportional to E(-2) and the flavor composition of the nu(e):nu(mu):nu(tau) flux is 1:1:1 at the Earth. The atmospheric neutrino analysis was optimized for lower energies. A total of 12 events were observed with energies above 5 TeV. The observed number of events is consistent with the expected background, within the uncertainties.
  •  
40.
  • Abbasi, R., et al. (författare)
  • First search for extremely high energy cosmogenic neutrinos with the IceCube Neutrino Observatory
  • 2010
  • Ingår i: Physical review. D, Particles, fields, gravitation, and cosmology. - 1550-7998. ; 82:7, s. 072003-
  • Tidskriftsartikel (refereegranskat)abstract
    • We report on the results of the search for extremely-high energy neutrinos with energies above 10(7) GeV obtained with the partially (similar to 30%) constructed IceCube in 2007. From the absence of signal events in the sample of 242.1 days of effective live time, we derive a 90% C.L. model independent differential upper limit based on the number of signal events per energy decade at E-2 phi(ve+v mu+v tau) similar or equal to 1.4 x 10(-6) GeV cm(-2) sec(-1) sr(-1) for neutrinos in the energy range from 3 x 10(7) to 3 x 10(9) GeV.
  •  
41.
  • Abbasi, R., et al. (författare)
  • IceCube sensitivity for low-energy neutrinos from nearby supernovae
  • 2011
  • Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 535, s. A109-
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper describes the response of the IceCube neutrino telescope located at the geographic south pole to outbursts of MeV neutrinos from the core collapse of nearby massive stars. IceCube was completed in December 2010 forming a lattice of 5160 photomultiplier tubes that monitor a volume of similar to 1 km(3) in the deep Antarctic ice for particle induced photons. The telescope was designed to detect neutrinos with energies greater than 100 GeV. Owing to subfreezing ice temperatures, the photomultiplier dark noise rates are particularly low. Hence IceCube can also detect large numbers of MeV neutrinos by observing a collective rise in all photomultiplier rates on top of the dark noise. With 2 ms timing resolution, IceCube can detect subtle features in the temporal development of the supernova neutrino burst. For a supernova at the galactic center, its sensitivity matches that of a background-free megaton-scale supernova search experiment. The sensitivity decreases to 20 standard deviations at the galactic edge (30 kpc) and 6 standard deviations at the Large Magellanic Cloud (50 kpc). IceCube is sending triggers from potential supernovae to the Supernova Early Warning System. The sensitivity to neutrino properties such as the neutrino hierarchy is discussed, as well as the possibility to detect the neutronization burst, a short outbreak of nu(e)'s released by electron capture on protons soon after collapse. Tantalizing signatures, such as the formation of a quark star or a black hole as well as the characteristics of shock waves, are investigated to illustrate IceCube's capability for supernova detection.
  •  
42.
  • Abbasi, R., et al. (författare)
  • IceTop : The surface component of IceCube
  • 2013
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 700, s. 188-220
  • Tidskriftsartikel (refereegranskat)abstract
    • IceTop, the surface component of the IceCube Neutrino Observatory at the South Pole, is an air shower array with an area of 1 km(2). The detector allows a detailed exploration of the mass composition of primary cosmic rays in the energy range from about 100 TeV to 1 EeV by exploiting the correlation between the shower energy measured in IceTop and the energy deposited by muons in the deep ice. In this paper we report on the technical design, construction and installation, the trigger and data acquisition systems as well as the software framework for calibration, reconstruction and simulation. Finally the first experience from commissioning and operating the detector and the performance as an air shower detector will be discussed.
  •  
43.
  • Abbasi, R., et al. (författare)
  • Lateral distribution of muons in IceCube cosmic ray events
  • 2013
  • Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 87:1, s. 012005-
  • Tidskriftsartikel (refereegranskat)abstract
    • In cosmic ray air showers, the muon lateral separation from the center of the shower is a measure of the transverse momentum that the muon parent acquired in the cosmic ray interaction. IceCube has observed cosmic ray interactions that produce muons laterally separated by up to 400 m from the shower core, a factor of 6 larger distance than previous measurements. These muons originate in high p(T) (> 2 GeV/c) interactions from the incident cosmic ray, or high-energy secondary interactions. The separation distribution shows a transition to a power law at large values, indicating the presence of a hard p(T) component that can be described by perturbative quantum chromodynamics. However, the rates and the zenith angle distributions of these events are not well reproduced with the cosmic ray models tested here, even those that include charm interactions. This discrepancy may be explained by a larger fraction of kaons and charmed particles than is currently incorporated in the simulations. DOI: 10.1103/PhysRevD.87.012005
  •  
44.
  • Abbasi, R., et al. (författare)
  • Limits on a muon flux from Kaluza-Klein dark matter annihilations in the Sun from the IceCube 22-string detector
  • 2010
  • Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 81:5, s. 057101-
  • Tidskriftsartikel (refereegranskat)abstract
    • A search for muon neutrinos from Kaluza-Klein dark matter annihilations in the Sun has been performed with the 22-string configuration of the IceCube 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 lightest Kaluza-Klein particle (LKP) WIMPs in the Sun and converted to limits on the LKP-proton cross sections for LKP masses in the range 250-3000 GeV. These results are the most stringent limits to date on LKP annihilation in the Sun.
  •  
45.
  • Abbasi, R., et al. (författare)
  • Limits on Neutrino Emission from Gamma-Ray Bursts with the 40 String IceCube Detector
  • 2011
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 106:14, s. 141101-
  • Tidskriftsartikel (refereegranskat)abstract
    • IceCube has become the first neutrino telescope with a sensitivity below the TeV neutrino flux predicted from gamma-ray bursts if gamma-ray bursts are responsible for the observed cosmic-ray flux above 10(18) eV. Two separate analyses using the half-complete IceCube detector, one a dedicated search for neutrinos from p gamma interactions in the prompt phase of the gamma-ray burst fireball and the other a generic search for any neutrino emission from these sources over a wide range of energies and emission times, produced no evidence for neutrino emission, excluding prevailing models at 90% confidence.
  •  
46.
  • Abbasi, R., et al. (författare)
  • Measurement of acoustic attenuation in South Pole ice
  • 2011
  • Ingår i: Astroparticle physics. - : Elsevier BV. - 0927-6505 .- 1873-2852. ; 34:6, s. 382-393
  • Tidskriftsartikel (refereegranskat)abstract
    • 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 +/- 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 equivalent to 1/alpha of similar to 300 m with 20% uncertainty. No significant depth or frequency dependence has been found.
  •  
47.
  • Abbasi, R., et al. (författare)
  • Measurement of sound speed vs. depth in South Pole ice for neutrino astronomy
  • 2010
  • Ingår i: Astroparticle physics. - : Elsevier BV. - 0927-6505 .- 1873-2852. ; 33:5-6, s. 277-286
  • Tidskriftsartikel (refereegranskat)abstract
    • We have measured the speed of both pressure waves and shear waves as a function of depth between 80 and 500 m depth in South Pole ice with better than 1% precision. The measurements were made using the South Pole Acoustic Test Setup (SPATS), an array of transmitters and sensors deployed in the ice at the South Pole in order to measure the acoustic properties relevant to acoustic detection of astrophysical neutrinos. The transmitters and sensors use piezoceramics operating at similar to 5-25 kHz. Between 200 m and 500 m depth, the measured profile is consistent with zero variation of the sound speed with depth, resulting in zero refraction, for both pressure and shear waves. We also performed a complementary study featuring an explosive signal propagating vertically from 50 to 2250 m depth, from which we determined a value for the pressure wave speed consistent with that determined for shallower depths, higher frequencies, and horizontal propagation with the SPATS sensors. The sound speed profile presented here can be used to achieve good acoustic source position and emission time reconstruction in general, and neutrino direction and energy reconstruction in particular. The reconstructed quantities could also help separate neutrino signals from background. (C) 2010 Elsevier B.V. All rights reserved.
  •  
48.
  • Abbasi, R., et al. (författare)
  • Measurement of the anisotropy of cosmic-ray arrival directions with icecube
  • 2010
  • Ingår i: The Astrophysical Journal Letters. - 2041-8205. ; 718, s. L194-L198
  • Tidskriftsartikel (refereegranskat)abstract
    • We report the first observation of an anisotropy in the arrival direction of cosmic rays with energies in the multi-TeV region in the Southern sky using data from the IceCube detector. Between 2007 June and 2008 March, the partially deployed IceCube detector was operated in a configuration with 1320 digital optical sensors distributed over 22 strings at depths between 1450 and 2450 m inside the Antarctic ice. IceCube is a neutrino detector, but the data are dominated by a large background of cosmic-ray muons. Therefore, the background data are suitable for high-statistics studies of cosmic rays in the southern sky. The data include 4.3 billion muons produced by downward-going cosmic-ray interactions in the atmosphere; these events were reconstructed with a median angular resolution of 3 degrees and a median energy of similar to 20 TeV. Their arrival direction distribution exhibits an anisotropy in right ascension with a first-harmonic amplitude of (6.4 +/- 0.2 stat. +/- 0.8 syst.) x 10(-4).
  •  
49.
  • Abbasi, R., et al. (författare)
  • Measurement of the atmospheric neutrino energy spectrum from 100 GeV to 400 TeV with IceCube
  • 2011
  • Ingår i: Physical Review D - Particles, Fields, Gravitation and Cosmology. - 1550-7998 .- 1550-2368. ; 83:1, s. 012001-
  • Tidskriftsartikel (refereegranskat)abstract
    • A measurement of the atmospheric muon neutrino energy spectrum from 100 GeV to 400 TeV was performed using a data sample of about 18 000 up-going atmospheric muon neutrino events in IceCube. Boosted decision trees were used for event selection to reject misreconstructed atmospheric muons and obtain a sample of up-going muon neutrino events. Background contamination in the final event sample is less than 1%. This is the first measurement of atmospheric neutrinos up to 400 TeV, and is fundamental to understanding the impact of this neutrino background on astrophysical neutrino observations with IceCube. The measured spectrum is consistent with predictions for the atmospheric nu(mu) + (nu) over bar (mu) flux.
  •  
50.
  • Abbasi, R., et al. (författare)
  • Multiyear search for dark matter annihilations in the Sun with the AMANDA-II and IceCube detectors
  • 2012
  • Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 85, s. 042002-
  • Tidskriftsartikel (refereegranskat)abstract
    • A search for an excess of muon neutrinos from dark matter annihilations in the Sun has been performed with the AMANDA-II neutrino telescope using data collected in 812 days of live time between 2001 and 2006 and 149 days of live time collected with the AMANDA-II and the 40-string configuration of IceCube during 2008 and early 2009. No excess over the expected atmospheric neutrino background has been observed. We combine these results with the previously published IceCube limits obtained with data taken during 2007 to obtain a total live time of 1065 days. We provide an upper limit at 90% confidence level 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 50-5000 GeV. We also derive a limit on the neutralino-proton spin-dependent and spin-independent cross section. The limits presented here improve the previous results obtained by the collaboration between a factor of 2 and 5, as well as extending the neutralino masses probed down to 50 GeV. The spin-dependent cross section limits are the most stringent so far for neutralino masses above 200 GeV, and well below direct search results in the mass range from 50 GeV to 5 TeV.
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