Научные публикации / Препринты

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КОЛЛЕКЦИЯ НАХОДИТСЯ В СТАДИИ РАЗРАБОТКИ

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A calibration study of local ice and optical sensor properties in IceCube
(2022) Abbasi, R.; Ackermann, M.; Adams, J.; Aguilar, J.; Besson, D.; Spiering, C.
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A convolutional neural network based cascade reconstruction for the IceCube Neutrino Observatory
(2021) Abbasi, R.; Ackermann, M.; Adams, J.; Aguilar, J. A.; Besson, D. Z.; Spiering, C.
© 2021 IOP Publishing Ltd and Sissa MedialabContinued improvements on existing reconstruction methods are vital to the success of high-energy physics experiments, such as the IceCube Neutrino Observatory. In IceCube, further challenges arise as the detector is situated at the geographic South Pole where computational resources are limited. However, to perform real-time analyses and to issue alerts to telescopes around the world, powerful and fast reconstruction methods are desired. Deep neural networks can be extremely powerful, and their usage is computationally inexpensive once the networks are trained. These characteristics make a deep learning-based approach an excellent candidate for the application in IceCube. A reconstruction method based on convolutional architectures and hexagonally shaped kernels is presented. The presented method is robust towards systematic uncertainties in the simulation and has been tested on experimental data. In comparison to standard reconstruction methods in IceCube, it can improve upon the reconstruction accuracy, while reducing the time necessary to run the reconstruction by two to three orders of magnitude.
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A muon-track reconstruction exploiting stochastic losses for large-scale Cherenkov detectors
(2021) Abbasi, R.; Ackermann, M.; Adams, J.; Aguilar, J. A.; Besson, D. Z.
© 2021 The Author(s).IceCube is a cubic-kilometer Cherenkov telescope operating at the South Pole. The main goal of IceCube is the detection of astrophysical neutrinos and the identification of their sources. High-energy muon neutrinos are observed via the secondary muons produced in charge current interactions with nuclei in the ice. Currently, the best performing muon track directional reconstruction is based on a maximum likelihood method using the arrival time distribution of Cherenkov photons registered by the experiment's photomultipliers. A known systematic shortcoming of the prevailing method is to assume a continuous energy loss along the muon track. However at energies >1 TeV the light yield from muons is dominated by stochastic showers. This paper discusses a generalized ansatz where the expected arrival time distribution is parametrized by a stochastic muon energy loss pattern. This more realistic parametrization of the loss profile leads to an improvement of the muon angular resolution of up to 20% for through-going tracks and up to a factor 2 for starting tracks over existing algorithms. Additionally, the procedure to estimate the directional reconstruction uncertainty has been improved to be more robust against numerical errors.
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A New Search for Neutrino Point Sources with IceCube
(2022) Abbasi, R.; Ackermann, M.; Adams, J.; Aguilar, J.; Besson, D.; Spiering, C.
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A novel microstructure-based model to explain the IceCube ice anisotropy
(2022) Chirkin, D.; Rongen, M.; Abbasi, R.; Ackermann, M.; Besson, D.; Spiering, C.
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A Posterior Analysis on IceCube Double Pulse Tau Neutrino Candidates
(2022) Tian, W.; Abbasi, R.; Ackermann, M.; Adams, J.; Besson, D.; Spiering, C.
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A Search for MeV to TeV Neutrinos from Fast Radio Bursts with IceCube
(2020) Aartsen, M. G.; Ackermann, M.; Adams, J.; Aguilar, J. A.; Besson, D. Z.
We present two searches for IceCube neutrino events coincident with 28 fast radio bursts (FRBs) and 1 repeating FRB. The first improves on a previous IceCube analysis-searching for spatial and temporal correlation of events with FRBs at energies greater than roughly 50 GeV-by increasing the effective area by an order of magnitude. The second is a search for temporal correlation of MeV neutrino events with FRBs. No significant correlation is found in either search; therefore, we set upper limits on the time-integrated neutrino flux emitted by FRBs for a range of emission timescales less than one day. These are the first limits on FRB neutrino emission at the MeV scale, and the limits set at higher energies are an order-of-magnitude improvement over those set by any neutrino telescope.
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A Search for Neutrino Point-source Populations in 7 yr of IceCube Data with Neutrino-count Statistics
(2020) Aartsen, M. G.; Ackermann, M.; Adams, J.; Aguilar, J. A.; Besson, D. Z.
The presence of a population of point sources in a data set modifies the underlying neutrino-count statistics from the Poisson distribution. This deviation can be exactly quantified using the non-Poissonian template fitting technique, and in this work we present the first application of this approach to the IceCube high-energy neutrino data set. Using this method, we search in 7 yr of IceCube data for point-source populations correlated with the disk of the Milky Way, the Fermi bubbles, the Schlegel, Finkbeiner, and Davis dust map, or with the isotropic extragalactic sky. No evidence for such a population is found in the data using this technique, and in the absence of a signal, we establish constraints on population models with source-count distribution functions that can be described by a power law with a single break. The derived limits can be interpreted in the context of many possible source classes. In order to enhance the flexibility of the results, we publish the full posterior from our analysis, which can be used to establish limits on specific population models that would contribute to the observed IceCube neutrino flux.
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A Search for Neutrino Sources with Cascade Events in IceCube
(2022) Sclafani, S.; Huennefeld, M.; Abbasi, R.; Ackermann, M.; Adams, J.; Besson, D.; Spiering, C.
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A Search for Neutrinos from Decaying Dark Matter in Galaxy Clusters and Galaxies with IceCube
(2022) Jeong, M.; Abbasi, R.; Ackermann, M.; Besson, D.; Spiering, C.
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A Search for Time-dependent Astrophysical Neutrino Emission with IceCube Data from 2012 to 2017
(2021) Abbasi, R.; Ackermann, M.; Adams, J.; Aguilar, J. A.; Besson, D. Z.
High-energy neutrinos are unique messengers of the high-energy universe, tracing the processes of cosmic ray acceleration. This paper presents analyses focusing on time-dependent neutrino point-source searches. A scan of the whole sky, making no prior assumption about source candidates, is performed, looking for a space and time clustering of high-energy neutrinos in data collected by the IceCube Neutrino Observatory between 2012 and 2017. No statistically significant evidence for a time-dependent neutrino signal is found with this search during this period, as all results are consistent with the background expectation. Within this study period, the blazar 3C 279, showed strong variability, inducing a very prominent gamma-ray flare observed in 2015 June. This event motivated a dedicated study of the blazar, which consists of searching for a time-dependent neutrino signal correlated with the gamma-ray emission. No evidence for a time-dependent signal is found. Hence, an upper limit on the neutrino fluence is derived, allowing us to constrain a hadronic emission model.
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A time-independent search for neutrinos from galaxy clusters with IceCube
(2022) Abbasi, R.; Ackermann, M.; Adams, J.; Aguilar, J.; Besson, D.; Spiering, C.
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A Time-Variability Test for Candidate Neutrino Sources Observed with IceCube
(2022) Dave, P.; Abbasi, R.; Ackermann, M.; Adams, J.; Besson, D.; Spiering, C.
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All-flavor constraints on nonstandard neutrino interactions and generalized matter potential with three years of IceCube DeepCore data
(2021) Abbasi, R.; Ackermann, M.; Adams, J.; Aguilar, J. A.; Besson, D. Z.; Spiering, C.
We report constraints on nonstandard neutrino interactions (NSI) from the observation of atmospheric neutrinos with IceCube, limiting all individual coupling strengths from a single dataset. Furthermore, IceCube is the first experiment to constrain flavor-violating and nonuniversal couplings simultaneously. Hypothetical NSI are generically expected to arise due to the exchange of a new heavy mediator particle. Neutrinos propagating in matter scatter off fermions in the forward direction with negligible momentum transfer. Hence the study of the matter effect on neutrinos propagating in the Earth is sensitive to NSI independently of the energy scale of new physics. We present constraints on NSI obtained with an all-flavor event sample of atmospheric neutrinos based on three years of IceCube DeepCore data. The analysis uses neutrinos arriving from all directions, with reconstructed energies between 5.6 GeV and 100 GeV. We report constraints on the individual NSI coupling strengths considered singly, allowing for complex phases in the case of flavor-violating couplings. This demonstrates that IceCube is sensitive to the full NSI flavor structure at a level competitive with limits from the global analysis of all other experiments. In addition, we investigate a generalized matter potential, whose overall scale and flavor structure are also constrained.
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Analysis framework for Multi-messenger Astronomy with IceCube
(2022) Abbasi, R.; Ackermann, M.; Adams, J.; Aguilar, J.; Besson, D.; Spiering, C.
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Camera Calibration for the IceCube Upgrade and Gen2
(2022) Abbasi, R.; Ackermann, M.; Adams, J.; Besson, D.; Spiering, C.; Kang, W.
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Characteristics of the Diffuse Astrophysical Electron and Tau Neutrino Flux with Six Years of IceCube High Energy Cascade Data
(2020) Aartsen, M. G.; Ackermann, M.; Adams, J.; Aguilar, J. A.; Besson, D. Z.
We report on the first measurement of the astrophysical neutrino flux using particle showers (cascades) in IceCube data from 2010-2015. Assuming standard oscillations, the astrophysical neutrinos in this dedicated cascade sample are dominated (similar to 90%) by electron and tau flavors. The flux, observed in the sensitive energy range from 16 TeV to 2.6 PeV, is consistent with a single power-law model as expected from Fermi-type acceleration of high energy particles at astrophysical sources. We find the flux spectral index to be gamma = 2.53 +/- 0.07 and a flux normalization for each neutrino flavor of phi(astro) = 1.66(-0.27)(+0.25) at E-0 = 100 TeV, in agreement with IceCube's complementary muon neutrino results and with all-neutrino flavor fit results. In the measured energy range we reject spectral indices gamma <= 2.28 at >= 3 sigma significance level. Because of high neutrino energy resolution and low atmospheric neutrino backgrounds, this analysis provides the most detailed characterization of the neutrino flux at energies below similar to 100 TeV compared to previous IceCube results. Results from fits assuming more complex neutrino flux models suggest a flux softening at high energies and a flux hardening at low energies (p value >= 0.06). The sizable and smooth flux measured below similar to 100 TeV remains a puzzle. In order to not violate the isotropic diffuse gamma-ray background as measured by the Fermi Large Area Telescope, it suggests the existence of astrophysical neutrino sources characterized by dense environments which are opaque to gamma rays.
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Characterization of the PeV astrophysical neutrino energy spectrum with IceCube using down-going tracks
(2022) Abbasi, R.; Ackermann, M.; Adams, J.; Aguilar, J.; Besson, D.; Spiering, C.
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Combined sensitivity to the neutrino mass ordering with JUNO, the IceCube Upgrade, and PINGU
(2020) Aartsen, M. G.; Ackermann, M.; Adams, J.; Aguilar, J. A.; Besson, D. Z.
The ordering of the neutrino mass eigenstates is one of the fundamental open questions in neutrino physics. While current-generation neutrino oscillation experiments are able to produce moderate indications on this ordering, upcoming experiments of the next generation aim to provide conclusive evidence. In this paper we study the combined performance of the two future multi-purpose neutrino oscillation experiments JUNO and the IceCube Upgrade, which employ two very distinct and complementary routes toward the neutrino mass ordering. The approach pursued by the 20 kt medium-baseline reactor neutrino experiment JUNO consists of a careful investigation of the energy spectrum of oscillated (nu) over bar (e) produced by ten nuclear reactor cores. The IceCube Upgrade, on the other hand, which consists of seven additional densely instrumented strings deployed in the center of IceCube DeepCore, will observe large numbers of atmospheric neutrinos that have undergone oscillations affected by Earth matter. In a joint fit with both approaches, tension occurs between their preferred mass-squared differences Delta m(31)(2) = m(3)(2) - m(1)(2) in within the wrong mass ordering. In the case of JUNO and the IceCube Upgrade, this allows to exclude the wrong ordering at > 5 sigma on a timescale of 3-7 years-even under circumstances that are unfavorable to the experiments individual sensitivities. For PINGU, a 26-string detector array designed as a potential low-energy extension to IceCube, the inverted ordering could be excluded within 1.5 years (3 years for the normal ordering) in a joint analysis.
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Combining Maximum-Likelihood with Deep Learning for Event Reconstruction in IceCube
(2022) Hunnefeld, M.; Abbasi, R.; Ackermann, M.; Adams, J.; Besson, D.; Spiering, C.