| 1. |
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Neutrino Physics : Proceedings of Nobel Symposium 129
- 2006
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Proceedings (redaktörskap) (refereegranskat)abstract
- PREFACE Nobel Symposium 129 on Neutrino Physics was held at Haga Slott in Enköping, Sweden during August 19–24, 2004. Invited to the symposium were around 40 globally leading researchers in the field of neutrino physics, both experimental and theoretical. In addition to these participants, some 30 local researchers and graduate students participated in the symposium. The dominant theme of the lectures was neutrino oscillations, which after several years were recently verified by results from the Super-Kamiokande detector in Kamioka, Japan and the SNO detector in Sudbury, Canada. Discussion focused especially on effects of neutrino oscillations derived from the presence of matter and the fact that three different neutrinos exist. Since neutrino oscillations imply that neutrinos have mass, this is the first experimental observation that fundamentally deviates from the standard model of particle physics. This is a challenge to both theoretical and experimental physics. The various oscillation parameters will be determined with increased precision in new, specially designed experiments. Theoretical physics is working intensively to insert the knowledge that neutrinos have mass into the theoretical models that describe particle physics. It will probably turn out that the discovery of neutrino oscillations signifies a breakthrough in the description of the very smallest constituents of matter. The lectures provided a very good description of the intensive situation in the field right now. The topics discussed also included mass models for neutrinos, neutrinos in extra dimensions as well as the `seesaw mechanism', which provides a good description of why neutrino masses are so small. Also discussed, besides neutrino oscillations, was the new field of neutrino astronomy. Among the questions that neutrino astronomy hopes to answer are what the dark matter in the Universe consists of and where cosmic radiation at extremely high energies comes from. For this purpose, large neutrino telescopes are built deep in the Antarctic ice, in the Baikal Lake, and in the Mediterranean Sea. Among prominent unanswered questions, highlighted as one of the most important, was whether neutrinos are Dirac or Majorana particles. By studying neutrino double beta decay, researchers hope to answer this question, but it will put very large demands on detectors. The programme also included ample time for lively and valuable discussions, which cannot normally be held at ordinary conferences. The symposium concluded with a round-table discussion, where participants discussed the future of neutrino physics.Without a doubt, neutrino physics today is moving toward a very exciting and interesting period. An important contribution to the success of the symposium was the wonderful setting that the Haga Slott manor house hotel and conference center offered to the participants.
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| 2. |
- Aartsen, M. G., et al.
(författare)
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A Combined Maximum-Likelihood Analysis Of The High-Energy Astrophysical Neutrino Flux Measured With Icecube
- 2015
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 809:1
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Tidskriftsartikel (refereegranskat)abstract
- Evidence for an extraterrestrial flux of high-energy neutrinos has now been found in multiple searches with the IceCube detector. The first solid evidence was provided by a search for neutrino events with deposited energies greater than or similar to 30 TeV and interaction vertices inside the instrumented volume. Recent analyses suggest that the extraterrestrial flux extends to lower energies and is also visible with throughgoing, nu(mu)-induced tracks from the Northern Hemisphere. Here, we combine the results from six different IceCube searches for astrophysical neutrinos in a maximum-likelihood analysis. The combined event sample features high-statistics samples of shower-like and track-like events. The data are fit in up to three observables: energy, zenith angle, and event topology. Assuming the astrophysical neutrino flux to be isotropic and to consist of equal flavors at Earth, the all-flavor spectrum with neutrino energies between 25 TeV and 2.8 PeV is well described by an unbroken power law with best-fit spectral index -2.50 +/- 0.09 and a flux at 100 TeV of (6.7(-1.2)(+1.1)) x 10(-18) GeV-1 s(-1) sr(-1) cm(-2). Under the same assumptions, an unbroken power law with index -2 is disfavored with a significance of 3.8 sigma (p = 0.0066%) with respect to the best fit. This significance is reduced to 2.1 sigma (p = 1.7%) if instead we compare the best fit to a spectrum with index -2 that has an exponential cut-off at high energies. Allowing the electron-neutrino flux to deviate from the other two flavors, we find a nu(e) fraction of 0.18 +/- 0.11 at Earth. The sole production of electron neutrinos, which would be characteristic of neutron-decay-dominated sources, is rejected with a significance of 3.6 sigma ( p = 0.014%).
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| 3. |
- Aartsen, M. G., et al.
(författare)
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An All-Sky Search For Three Flavors Of Neutrinos From Gamma-Ray Bursts With The Icecube Neutrino Observatory
- 2016
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 824:2
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Tidskriftsartikel (refereegranskat)abstract
- We present the results and methodology of a search for neutrinos produced in the decay of charged pions created in interactions between protons and gamma-rays during the prompt emission of 807 gamma-ray bursts (GRBs) over the entire sky. This three-year search is the first in IceCube for shower-like Cherenkov light patterns from electron, muon, and tau neutrinos correlated with GRBs. We detect five low-significance events correlated with five GRBs. These events are consistent with the background expectation from atmospheric muons and neutrinos. The results of this search in combination with those of IceCube's four years of searches for track-like Cherenkov light patterns from muon neutrinos correlated with Northern-Hemisphere GRBs produce limits that tightly constrain current models of neutrino and ultra high energy cosmic ray production in GRB fireballs.
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| 4. |
- Aartsen, M. G., et al.
(författare)
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Anisotropy In Cosmic-Ray Arrival Directions In The Southern Hemisphere Based On Six Years Of Data From The Icecube Detector
- 2016
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 826:2
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Tidskriftsartikel (refereegranskat)abstract
- The IceCube Neutrino Observatory accumulated a total of 318 billion cosmic-ray-induced muon events between 2009 May and 2015 May. This data set was used for a detailed analysis of the sidereal anisotropy in the arrival directions of cosmic rays in the TeV to PeV energy range. The observed global sidereal anisotropy features large regions of relative excess and deficit, with amplitudes of the order of 10(-3) up to about 100 TeV. A decomposition of the arrival direction distribution into spherical harmonics shows that most of the power is contained in the low-multipole (l <= 4) moments. However, higher multipole components are found to be statistically significant down to an angular scale of less than 10 degrees, approaching the angular resolution of the detector. Above 100 TeV, a change in the morphology of the arrival direction distribution is observed, and the anisotropy is characterized by a wide relative deficit whose amplitude increases with primary energy up to at least 5 PeV, the highest energies currently accessible to IceCube. No time dependence of the large-and small-scale structures is observed in the period of six years covered by this analysis. The high-statistics data set reveals more details of the properties of the anisotropy and is potentially able to shed light on the various physical processes that are responsible for the complex angular structure and energy evolution.
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| 5. |
- Aartsen, M. G., et al.
(författare)
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Atmospheric and astrophysical neutrinos above 1 TeV interacting in IceCube
- 2015
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Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 91:2, s. 022001-
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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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| 6. |
- Aartsen, M. G., et al.
(författare)
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Characterization of the atmospheric muon flux in IceCube
- 2016
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Ingår i: Astroparticle physics. - : Elsevier BV. - 0927-6505 .- 1873-2852. ; 78, s. 1-27
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Tidskriftsartikel (refereegranskat)abstract
- Muons produced in atmospheric cosmic ray showers account for the by far dominant part of the event yield in large-volume underground particle detectors. The IceCube detector, with an instrumented volume of about a cubic kilometer, has the potential to conduct unique investigations on atmospheric muons by exploiting the large collection area and the possibility to track particles over a long distance. Through detailed reconstruction of energy deposition along the tracks, the characteristics of muon bundles can be quantified, and individual particles of exceptionally high energy identified. The data can then be used to constrain the cosmic ray primary flux and the contribution to atmospheric lepton fluxes from prompt decays of short-lived hadrons. In this paper, techniques for the extraction of physical measurements from atmospheric muon events are described and first results are presented. The multiplicity spectrum of TeV muons in cosmic ray air showers for primaries in the energy range from the knee to the ankle is derived and found to be consistent with recent results from surface detectors. The single muon energy spectrum is determined up to PeV energies and shows a clear indication for the emergence of a distinct spectral component from prompt decays of short-lived hadrons. The magnitude of the prompt flux, which should include a substantial contribution from light vector meson di-muon decays, is consistent with current theoretical predictions. The variety of measurements and high event statistics can also be exploited for the evaluation of systematic effects. In the course of this study, internal inconsistencies in the zenith angle distribution of events were found which indicate the presence of an unexplained effect outside the currently applied range of detector systematics. The underlying cause could be related to the hadronic interaction models used to describe muon production in air showers.
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| 7. |
- Aartsen, M. G., et al.
(författare)
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Determining neutrino oscillation parameters from atmospheric muon neutrino disappearance with three years of IceCube DeepCore data
- 2015
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Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 91:7
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Tidskriftsartikel (refereegranskat)abstract
- We present a measurement of neutrino oscillations via atmospheric muon neutrino disappearance with three years of data of the completed IceCube neutrino detector. DeepCore, a region of denser IceCube instrumentation, enables the detection and reconstruction of atmospheric muon neutrinos between 10 and 100 GeV, where a strong disappearance signal is expected. The IceCube detector volume surrounding DeepCore is used as a veto region to suppress the atmospheric muon background. Neutrino events are selected where the detected Cherenkov photons of the secondary particles minimally scatter, and the neutrino energy and arrival direction are reconstructed. Both variables are used to obtain the neutrino oscillation parameters from the data, with the best fit given by Delta m(32)(2) = 2.72(-0.20)(+0.19) x 10(-3) eV(2) and sin(2)theta(23) = 0.53(-0.12)(+0.09) (normal mass ordering assumed). The results are compatible, and comparable in precision, to those of dedicated oscillation experiments.
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| 8. |
- Aartsen, M. G., et al.
(författare)
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Development of a general analysis and unfolding scheme and its application to measure the energy spectrum of atmospheric neutrinos with IceCube
- 2015
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Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 75:3
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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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| 9. |
- Aartsen, M. G., et al.
(författare)
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Energy reconstruction methods in the IceCube neutrino telescope
- 2014
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Ingår i: Journal of Instrumentation. - 1748-0221. ; 9, s. P03009-
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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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| 10. |
- Aartsen, M. G., et al.
(författare)
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Evidence for Astrophysical Muon Neutrinos from the Northern Sky with IceCube
- 2015
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 115:8
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Tidskriftsartikel (refereegranskat)abstract
- Results from the IceCube Neutrino Observatory have recently provided compelling evidence for the existence of a high energy astrophysical neutrino flux utilizing a dominantly Southern Hemisphere data set consisting primarily of nu(e) and nu(tau) charged-current and neutral-current ( cascade) neutrino interactions. In the analysis presented here, a data sample of approximately 35 000 muon neutrinos from the Northern sky is extracted from data taken during 659.5 days of live time recorded between May 2010 and May 2012. While this sample is composed primarily of neutrinos produced by cosmic ray interactions in Earth's atmosphere, the highest energy events are inconsistent with a hypothesis of solely terrestrial origin at 3.7 sigma significance. These neutrinos can, however, be explained by an astrophysical flux per neutrino flavor at a level of Phi(E-nu) = 9.9(-3.4)(+3.9) x 10(-19) GeV-1 cm(-2) sr(-1) s(-1) (E-nu/100 TeV)(-2), consistent with IceCube's Southern-Hemisphere-dominated result. Additionally, a fit for an astrophysical flux with an arbitrary spectral index is performed. We find a spectral index of 2.2(-0.2)(+0.2), which is also in good agreement with the Southern Hemisphere result.
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| 11. |
- Aartsen, M. G., et al.
(författare)
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Evidence for High-Energy Extraterrestrial Neutrinos at the IceCube Detector
- 2013
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 342:6161, s. 947-
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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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| 12. |
- Aartsen, M. G., et al.
(författare)
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First Observation of PeV-Energy Neutrinos with IceCube
- 2013
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 111:2, s. 021103-
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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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| 13. |
- Aartsen, M. G., et al.
(författare)
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Flavor Ratio of Astrophysical Neutrinos above 35 TeV in IceCube
- 2015
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 114:17
-
Tidskriftsartikel (refereegranskat)abstract
- A diffuse flux of astrophysical neutrinos above 100 TeV has been observed at the IceCube Neutrino Observatory. Here we extend this analysis to probe the astrophysical flux down to 35 TeV and analyze its flavor composition by classifying events as showers or tracks. Taking advantage of lower atmospheric backgrounds for showerlike events, we obtain a shower-biased sample containing 129 showers and 8 tracks collected in three years from 2010 to 2013. We demonstrate consistency with the (f(e) : f(mu) : f(tau))(circle plus) approximate to (1 : 1 : 1)(circle plus) flavor ratio at Earth commonly expected from the averaged oscillations of neutrinos produced by pion decay in distant astrophysical sources. Limits are placed on nonstandard flavor compositions that cannot be produced by averaged neutrino oscillations but could arise in exotic physics scenarios. A maximally tracklike composition of (0 : 1 : 0)(circle plus) is excluded at 3.3 sigma, and a purely showerlike composition of (1 : 0 : 0)(circle plus) is excluded at 2.3 sigma.
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| 14. |
- Aartsen, M. G., et al.
(författare)
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IceCube search for dark matter annihilation in nearby galaxies and galaxy clusters
- 2013
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Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 88:12
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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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| 15. |
- Aartsen, M. G., et al.
(författare)
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Improved limits on dark matter annihilation in the Sun with the 79-string IceCube detector and implications for supersymmetry
- 2016
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Ingår i: Journal of Cosmology and Astroparticle Physics. - : IOP Publishing. - 1475-7516. ; :4
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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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| 16. |
- Aartsen, M. G., et al.
(författare)
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Improvement in fast particle track reconstruction with robust statistics
- 2014
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 736, s. 143-149
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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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| 17. |
- Aartsen, M. G., et al.
(författare)
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Measurement of Atmospheric Neutrino Oscillations with IceCube
- 2013
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 111:8, s. 081801-
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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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| 18. |
- Aartsen, M. G., et al.
(författare)
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Measurement of South Pole ice transparency with the IceCube LED calibration system
- 2013
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 711, s. 73-89
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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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| 19. |
- Aartsen, M. G., et al.
(författare)
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Measurement of the Atmospheric nu(e) Flux in IceCube
- 2013
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 110:15, s. 151105-
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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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| 20. |
- Aartsen, M. G., et al.
(författare)
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Measurement of the Atmospheric nu(e) Spectrum with IceCube
- 2015
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Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 91:12
-
Tidskriftsartikel (refereegranskat)abstract
- We present a measurement of the atmospheric nu(e) spectrum at energies between 0.1 and 100 TeV using data from the first year of the complete IceCube detector. Atmospheric nu(e) originate mainly from the decays of kaons produced in cosmic-ray air showers. This analysis selects 1078 fully contained events in 332 days of live time, and then identifies those consistent with particle showers. A likelihood analysis with improved event selection extends our previous measurement of the conventional v(e) fluxes to higher energies. The data constrain the conventional nu(e) flux to be 1.3(-0.3)(+0.4) times a baseline prediction from a Honda's calculation, including the knee of the cosmic-ray spectrum. A fit to the kaon contribution (xi) to the neutrino flux finds a kaon component that is xi = 1.3(-0.4)(+0.5) times the baseline value. The fitted/measured prompt neutrino flux from charmed hadron decays strongly depends on the assumed astrophysical flux and shape. If the astrophysical component follows a power law, the result for the prompt flux is 0.0(-0.0)(+3.0) times a calculated flux based on the work by Enberg, Reno, and Sarcevic.
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| 21. |
- Aartsen, M. G., et al.
(författare)
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Measurement of the cosmic ray energy spectrum with IceTop-73
- 2013
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Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 88:4, s. 042004-
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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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| 22. |
- Aartsen, M. G., et al.
(författare)
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Multipole analysis of IceCube data to search for dark matter accumulated in the Galactic halo
- 2015
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Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 75:1
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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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| 23. |
- Aartsen, M. G., et al.
(författare)
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Neutrino oscillation studies with IceCube-DeepCore
- 2016
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Ingår i: Nuclear Physics B. - : Elsevier BV. - 0550-3213 .- 1873-1562. ; 908, s. 161-177
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Tidskriftsartikel (refereegranskat)abstract
- IceCube, a gigaton-scale neutrino detector located at the South Pole, was primarily designed to search for astrophysical neutrinos with energies of PeV and higher. This goal has been achieved with the detection of the highest energy neutrinos to date. At the other end of the energy spectrum, the DeepCore extension lowers the energy threshold of the detector to approximately 10 GeV and opens the door for oscillation studies using atmospheric neutrinos. An analysis of the disappearance of these neutrinos has been completed, with the results produced being complementary with dedicated oscillation experiments. Following a review of the detector principle and performance, the method used to make these calculations, as well as the results, is detailed. Finally, the future prospects of IceCube-DeepCore and the next generation of neutrino experiments at the South Pole (IceCube-Gen2, specifically the PINGU sub-detector) are briefly discussed.
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| 24. |
- Aartsen, M. G., et al.
(författare)
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Observation of Cosmic-Ray Anisotropy with the Icetop Air Shower Array
- 2013
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 765:1, s. 55-
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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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| 25. |
- Aartsen, M. G., et al.
(författare)
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Observation of High-Energy Astrophysical Neutrinos in Three Years of IceCube Data
- 2014
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 113:10, s. 101101-
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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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