SwePub
Sök i SwePub databas

  Utökad sökning

Träfflista för sökning "WFRF:(Wendt C) "

Sökning: WFRF:(Wendt C)

  • Resultat 21-30 av 245
Sortera/gruppera träfflistan
   
NumreringReferensOmslagsbildHitta
21.
  • Aartsen, M. G., et al. (författare)
  • Detection of the Temporal Variation of the Sun's Cosmic Ray Shadow with the IceCube Detector
  • 2019
  • Ingår i: Astrophysical Journal. - : IOP PUBLISHING LTD. - 0004-637X .- 1538-4357. ; 872:2
  • Tidskriftsartikel (refereegranskat)abstract
    • We report on the observation of a deficit in the cosmic ray flux from the directions of the Moon and Sun with five years of data taken by the IceCube Neutrino Observatory. Between 2010 May and 2011 May the IceCube detector operated with 79 strings deployed in the glacial ice at the South Pole, and with 86 strings between 2011 May and 2015 May. A binned analysis is used to measure the relative deficit and significance of the cosmic ray shadows. Both the cosmic ray Moon and Sun shadows are detected with high statistical significance (>10σ) for each year. The results for the Moon shadow are consistent with previous analyses and verify the stability of the IceCube detector over time. This work represents the first observation of the Sun shadow with the IceCube detector. We show that the cosmic ray shadow of the Sun varies with time. These results make it possible to study cosmic ray transport near the Sun with future data from IceCube.
  •  
22.
  • Aartsen, M. G., et al. (författare)
  • Measurement of atmospheric tau neutrino appearance with IceCube DeepCore
  • 2019
  • Ingår i: Physical Review D. - : AMER PHYSICAL SOC. - 2470-0010 .- 2470-0029. ; 99:3
  • Tidskriftsartikel (refereegranskat)abstract
    • We present a measurement of atmospheric tau neutrino appearance from oscillations with three years of data from the DeepCore subarray of the IceCube Neutrino Observatory. This analysis uses atmospheric neutrinos from the full sky with reconstructed energies between 5.6 and 56 GeV to search for a statistical excess of cascadelike neutrino events which are the signature of nu(tau) interactions. For CC thorn NC (CC-only) interactions, we measure the tau neutrino normalization to be 0.73(-0.24)(+0.30) (0.57(-0.30)(+0.36)) and exclude the absence of tau neutrino oscillations at a significance of 3.2 sigma (2.0 sigma) These results are consistent with, and of similar precision to, a confirmatory IceCube analysis also presented, as well as measurements performed by other experiments.
  •  
23.
  • Aartsen, M. G., et al. (författare)
  • Search for steady point-like sources in the astrophysical muon neutrino flux with 8 years of IceCube data
  • 2019
  • Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 79:3
  • Tidskriftsartikel (refereegranskat)abstract
    • The IceCube Collaboration has observed a high-energy astrophysical neutrino flux and recently found evidence for neutrino emission from the blazar TXS 0506+056. These results open a new window into the high-energy universe. However, the source or sources of most of the observed flux of astrophysical neutrinos remains uncertain. Here, a search for steady point-like neutrino sources is performed using an unbinned likelihood analysis. The method searches for a spatial accumulation of muon-neutrino events using the very high-statistics sample of about 497,000 neutrinos recorded by IceCube between 2009 and 2017. The median angular resolution is approximate to 1 degrees at 1 TeV and improves to approximate to 0.3 degrees for neutrinos with an energy of 1 PeV. Compared to previous analyses, this search is optimized for point-like neutrino emission with the same flux-characteristics as the observed astrophysical muon-neutrino flux and introduces an improved event-reconstruction and parametrization of the background. The result is an improvement in sensitivity to the muon-neutrino flux compared to the previous analysis of approximate to 35% assuming an E-2 spectrum. The sensitivity on the muon-neutrino flux is at a level of E2dN/dE=310-13s-1. No new evidence for neutrino sources is found in a full sky scan and in an a priori candidate source list that is motivated by gamma-ray observations. Furthermore, no significant excesses above background are found from populations of sub-threshold sources. The implications of the non-observation for potential source classes are discussed.
  •  
24.
  • Abbasi, R., et al. (författare)
  • Solar energetic particle spectrum on 2006 December 13 determined by IceTop
  • 2008
  • Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 689:1, s. L65-L68
  • Tidskriftsartikel (refereegranskat)abstract
    • On 2006 December 13 the IceTop air shower array at the South Pole detected a major solar particle event. By numerically simulating the response of the IceTop tanks, which are thick Cerenkov detectors with multiple thresholds deployed at high altitude with no geomagnetic cutoff, we determined the particle energy spectrum in the energy range 0.6-7.6 GeV. This is the first such spectral measurement using a single instrument with a well-defined viewing direction. We compare the IceTop spectrum and its time evolution with previously published results and outline plans for improved resolution of future solar particle spectra.
  •  
25.
  •  
26.
  • Aartsen, M. G., et al. (författare)
  • Constraints on Minute-Scale Transient Astrophysical Neutrino Sources
  • 2019
  • Ingår i: Physical Review Letters. - : AMER PHYSICAL SOC. - 0031-9007 .- 1079-7114. ; 122:5
  • Tidskriftsartikel (refereegranskat)abstract
    • High-energy neutrino emission has been predicted for several short-lived astrophysical transients including gamma-ray bursts (GRBs), core-collapse supernovae with choked jets, and neutron star mergers. IceCube's optical and x-ray follow-up program searches for such transient sources by looking for two or more muon neutrino candidates in directional coincidence and arriving within 100 s. The measured rate of neutrino alerts is consistent with the expected rate of chance coincidences of atmospheric background events and no likely electromagnetic counterparts have been identified in Swift follow-up observations. Here, we calculate generic bounds on the neutrino flux of short-lived transient sources. Assuming an E-2.5 neutrino spectrum, we find that the neutrino flux of rare sources, like long gamma-ray bursts, is constrained to < 5% of the detected astrophysical flux and the energy released in neutrinos (100 GeV to 10 PeV) by a median bright GRB-like source is < 10(52.5) erg. For a harder E-2.13 neutrino spectrum up to 30% of the flux could be produced by GRBs and the allowed median source energy is < 10(52) erg. A hypothetical population of transient sources has to be more common than 10(-5) Mpc(-3) yr(-1) (5 x 10(-8) Mpc(-3) yr(-1) for the E-2.13 spectrum) to account for the complete astrophysical neutrino flux.
  •  
27.
  • Aartsen, M. G., et al. (författare)
  • Differential limit on the extremely-high-energy cosmic neutrino flux in the presence of astrophysical background from nine years of IceCube data
  • 2018
  • Ingår i: Physical Review D. - : AMER PHYSICAL SOC. - 2470-0010 .- 2470-0029. ; 98:6
  • Tidskriftsartikel (refereegranskat)abstract
    • We report a quasidifferential upper limit on the extremely-high-energy (EHE) neutrino flux above 5 x 10(6) GeV based on an analysis of nine years of IceCube data. The astrophysical neutrino flux measured by IceCube extends to PeV energies, and it is a background flux when searching for an independent signal flux at higher energies, such as the cosmogenic neutrino signal. We have developed a new method to place robust limits on the EHE neutrino flux in the presence of an astrophysical background, whose spectrum has yet to be understood with high precision at PeV energies. A distinct event with a deposited energy above 10(6) GeV was found in the new two-year sample, in addition to the one event previously found in the seven-year EHE neutrino search. These two events represent a neutrino flux that is incompatible with predictions for a cosmogenic neutrino flux and are considered to be an astrophysical background in the current study. The obtained limit is the most stringent to date in the energy range between 5 x 10(6) and 2 x 10(10) GeV. This result constrains neutrino models predicting a three-flavor neutrino flux of E-nu(2)phi(nu e+nu mu+nu tau) similar or equal to 2 x 10(-8) GeV/cm(2) sec sr at 10(9) GeV. A significant part of the parameter space for EHE neutrino production scenarios assuming a proton-dominated composition of ultra-high-energy cosmic rays is disfavored independently of uncertain models of the extragalactic background light which previous IceCube constraints partially relied on.
  •  
28.
  • 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.
  •  
29.
  • Aartsen, M. G., et al. (författare)
  • Lowering Icecube'S Energy Threshold For Point Source Searches In The Southern Sky
  • 2016
  • Ingår i: Astrophysical Journal Letters. - 2041-8205 .- 2041-8213. ; 824:2
  • Tidskriftsartikel (refereegranskat)abstract
    • Observation of a point source of astrophysical neutrinos would be a "smoking gun" signature of a cosmic-ray accelerator. While IceCube has recently discovered a diffuse flux of astrophysical neutrinos, no localized point source has been observed. Previous IceCube searches for point sources in the southern sky were restricted by either an energy threshold above a few hundred TeV or poor neutrino angular resolution. Here we present a search for southern sky point sources with greatly improved sensitivities to neutrinos with energies below 100 TeV. By selecting charged-current nu(mu) interacting inside the detector, we reduce the atmospheric background while retaining efficiency for astrophysical neutrino-induced events reconstructed with sub-degree angular resolution. The new event sample covers three years of detector data and leads to a factor of 10 improvement in sensitivity to point sources emitting below 100 TeV in the southern sky. No statistically significant evidence of point sources was found, and upper limits are set on neutrino emission from individual sources. A posteriori analysis of the highest-energy (similar to 100 TeV) starting event in the sample found that this event alone represents a 2.8 sigma deviation from the hypothesis that the data consists only of atmospheric background.
  •  
30.
  • Aartsen, M. G., et al. (författare)
  • Measurements using the inelasticity distribution of multi-TeV neutrino interactions in IceCube
  • 2019
  • Ingår i: Physical Review D. - : AMER PHYSICAL SOC. - 2470-0010 .- 2470-0029. ; 99:3
  • Tidskriftsartikel (refereegranskat)abstract
    • Inelasticity, the fraction of a neutrino's energy transferred to hadrons, is a quantity of interest in the study of astrophysical and atmospheric neutrino interactions at multi-TeV energies with IceCube. In this work, a sample of contained neutrino interactions in IceCube is obtained from five years of data and classified as 2650 tracks and 965 cascades. Tracks arise predominantly from charged-current nu(mu) interactions, and we demonstrate that we can reconstruct their energy and inelasticity. The inelasticity distribution is found to be consistent with the calculation of Cooper-Sarkar et al. across the energy range from similar to 1 to similar to 100 TeV. Along with cascades from neutrinos of all flavors, we also perform a fit over the energy, zenith angle, and inelasticity distribution to characterize the flux of astrophysical and atmospheric neutrinos. The energy spectrum of diffuse astrophysical neutrinos is described well by a power law in both track and cascade samples, and a best-fit index gamma = 2.62 +/- 0.07 is found in the energy range from 3.5 TeV to 2.6 PeV. Limits are set on the astrophysical flavor composition and are compatible with a ratio of (1/3 : 1/3 : 1/3)(circle plus). Exploiting the distinct inelasticity distribution of nu(mu) and (nu) over bar (mu) interactions, the atmospheric nu(mu) to (nu) over bar (mu) flux ratio in the energy range from 770 GeV to 21 TeV is found to be 0.77(-0.25)(+0.44) times the calculation by Honda et al. Lastly, the inelasticity distribution is also sensitive to neutrino charged-current charm production. The data are consistent with a leading-order calculation, with zero charm production excluded at 91% confidence level. Future analyses of inelasticity distributions may probe new physics that affects neutrino interactions both in and beyond the Standard Model.
  •  
Skapa referenser, mejla, bekava och länka
  • Resultat 21-30 av 245
Typ av publikation
tidskriftsartikel (237)
konferensbidrag (6)
forskningsöversikt (1)
Typ av innehåll
refereegranskat (238)
övrigt vetenskapligt/konstnärligt (6)
Författare/redaktör
Kolanoski, H. (141)
Helbing, K. (141)
Hoshina, K. (141)
Karle, A. (141)
Montaruli, T. (141)
Olivas, A. (141)
visa fler...
Rawlins, K. (141)
Resconi, E. (141)
Rhode, W. (141)
Rott, C. (141)
Ryckbosch, D. (141)
Schmidt, T. (141)
Stanev, T. (141)
Bai, X. (140)
Kowalski, M. (140)
Berley, D. (140)
Bernardini, E. (140)
Blaufuss, E. (140)
Desiati, P. (140)
Gerhardt, L. (140)
Halzen, F. (140)
Hanson, K. (140)
Ishihara, A. (140)
Karg, T. (140)
Madsen, J. (140)
Seckel, D. (140)
Seunarine, S. (140)
Spiering, C. (140)
Adams, J. (138)
Kappes, A. (138)
Meagher, K. (138)
Van Eijndhoven, N. (137)
De Clercq, C. (137)
Hoffman, K. D. (137)
Hultqvist, K. (137)
Kiryluk, J. (137)
Maruyama, R. (137)
Sarkar, S. (137)
Fazely, A. R. (136)
Gallagher, J. (136)
Grant, D. (136)
Przybylski, G. T. (136)
Barwick, S. W. (135)
Bay, R. (135)
Diaz-Velez, J. C. (135)
Hickford, S. (135)
Hill, G. C. (135)
Mase, K. (135)
Nahnhauer, R. (135)
Spiczak, G. M. (135)
visa färre...
Lärosäte
Uppsala universitet (154)
Stockholms universitet (135)
Karolinska Institutet (53)
Lunds universitet (38)
Göteborgs universitet (11)
Linnéuniversitetet (10)
visa fler...
Chalmers tekniska högskola (8)
Kungliga Tekniska Högskolan (3)
Linköpings universitet (3)
Umeå universitet (2)
Jönköping University (2)
Luleå tekniska universitet (1)
Mittuniversitetet (1)
RISE (1)
Sophiahemmet Högskola (1)
visa färre...
Språk
Engelska (245)
Forskningsämne (UKÄ/SCB)
Naturvetenskap (174)
Medicin och hälsovetenskap (36)
Teknik (4)
Samhällsvetenskap (4)

År

Kungliga biblioteket hanterar dina personuppgifter i enlighet med EU:s dataskyddsförordning (2018), GDPR. Läs mer om hur det funkar här.
Så här hanterar KB dina uppgifter vid användning av denna tjänst.

 
pil uppåt Stäng

Kopiera och spara länken för att återkomma till aktuell vy