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TOPIC: IceCube

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Posts: 129165
Date:
 RE: IceCube Permalink Title: Cosmic Ray Physics with the IceCube Observatory Authors: Hermann Kolanoski, for the IceCube Collaboration The IceCube Neutrino Observatory with its 1-km³ in-ice detector and the 1-km² surface detector (IceTop) constitutes a three-dimensional cosmic ray detector well suited for general cosmic ray physics. Various measurements of cosmic ray properties, such as energy spectra, mass composition and anisotropies, have been obtained from analyses of air showers at the surface and/or atmospheric muons in the ice. Read more (988kb, PDF) __________________

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Posts: 129165
Date:
 IceCube Neutrino Observatory Permalink IceCube catches high-energy neutrino oscillations The IceCube Neutrino Observatory, a telescope at the South Pole that detects the subatomic particles known as neutrinos, has measured the highest-energy neutrino oscillations yet. Read more __________________

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Posts: 129165
Date:
 IceCube Permalink IceCube Neutrino Observatory explores origin of cosmic rays Although cosmic rays were discovered 100 years ago, their origin remains one of the most enduring mysteries in physics. Now, the IceCube Neutrino Observatory, a massive detector in Antarctica, is honing in on how the highest energy cosmic rays are produced. Read more __________________

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Posts: 129165
Date:
 Permalink Title: Icecube non-detection of GRBs: Constraints on the fireball properties Authors: Hao-Ning He, Ruo-Yu Liu, Xiang-Yu Wang, Shigehiro Nagataki, Kohta Murase, Zi-Gao Dai The increasingly deep limit on the neutrino emission from gamma-ray bursts (GRBs) with IceCube observations has reached the level that could put useful constraints on the fireball properties. We first present a revised analytic calculation of the neutrino flux, which predicts a flux an order of magnitude lower than that obtained by the IceCube collaboration. For benchmark model parameters (e.g. the bulk Lorentz factor is \Gamma=10^{2.5}, the observed variability time for long GRBs is t_v=0.01 s and the ratio between the energy in accelerated protons and in radiation is \eta_p=10 for every burst) in the standard internal shock scenario, the predicted neutrino flux from 215 bursts during the period of the 40-string and 59-string configurations is found to be a factor of ~3 below the IceCube sensitivity. However, if we accept the recently found inherent relation between the bulk Lorentz factor and burst energy, the expected neutrino flux increases significantly and the spectral peak shifts to lower energy. In this case, the non-detection then implies that the baryon loading ratio should be \eta_p<10 if the variability time of long GRBs is fixed to t_v=0.01 s. Instead, if we relax the standard internal shock scenario but keep to assume \eta_p=10, the non-detection constrains the dissipation radius to be R>4x10^{12} cm assuming the same dissipation radius for every burst and benchmark parameters for fireballs. We also calculate the diffuse neutrino flux from GRBs for different luminosity functions existing in literature. The expected flux exceeds the current IceCube limit for some luminosity functions, and thus the non-detection constrains \eta_p<10 in such cases when the variability time of long GRBs is fixed to t_v=0.01 s.Read more (96kb, PDF) __________________

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Posts: 129165
Date:
 Permalink Title: A Search for UHE Tau Neutrinos with IceCube Authors: IceCube Collaboration: R. Abbasi, Y. Abdou, T. Abu-Zayyad, M. Ackermann, J. Adams, J. A. Aguilar, M. Ahlers, D. Altmann, K. Andeen, J. Auffenberg, X. Bai, M. Baker, S. W. Barwick, V. Baum, R. Bay, K. Beattie, J. J. Beatty, S. Bechet, J. K. Becker, K.-H. Becker, M. Bell, M. L. Benabderrahmane, S. BenZvi, J. Berdermann, P. Berghaus, D. Berley, E. Bernardini, D. Bertrand, D. Z. Besson, D. Bindig, M. Bissok, E. Blaufuss, J. Blumenthal, D. J. Boersma, C. Bohm, D. Bose1, S. Böser, O. Botner, L. Brayeur, A. M. Brown, S. Buitink, K. S. Caballero-Mora, M. Carson, M. Casier, D. Chirkin, B. Christy, F. Clevermann, S. Cohen, D. F. Cowen, A. H. Cruz Silva, M. V. D'Agostino, M. Danninger, J. Daughhetee, J. C. Davis, C. De Clercq, T. Degner, F. Descamps, P. Desiati, G. de Vries-Uiterweerd, T. DeYoung, et al. (194 additional authors not shown) The first dedicated search for ultra-high energy (UHE) tau neutrinos of astrophysical origin was performed using the IceCube detector in its 22-string configuration. The search also had sensitivity to UHE electron and muon neutrinos. After application of all selection criteria to approximately 200 live-days of data, we expect a background of 0.60 ±0.19 (stat.) ^{+0.56}_{-0.58} (sys.) events and observe three events, which after inspection emerge as being compatible with background. Therefore, we set an upper limit on neutrinos of all flavors from UHE astrophysical sources at 90% CL of E^{2} \Phi(\nu_{x}) < 16.2 * 10^-8 GeV cm^-2 sr^-1 s^-1 over an estimated primary neutrino energy range of 340 TeV to 200 PeV. Read more (658kb, PDF) __________________

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Posts: 129165
Date:
 South Pole Acoustic Test Setup Permalink Title: Acoustic detection of astrophysical neutrinos in South Pole ice Authors: Justin Vandenbroucke When high-energy particles interact in dense media to produce a particle shower, most of the shower energy is deposited in the medium as heat. This causes the medium to expand locally and emit a shock wave with a medium-dependent peak frequency on the order of 10 kHz. In South Pole ice in particular, the elastic properties of the medium have been theorized to provide good coupling of particle energy to acoustic energy. The acoustic attenuation length has been theorized to be several km, which could enable a sparsely instrumented large-volume detector to search for rare signals from high-energy astrophysical neutrinos. We simulated a hybrid optical/radio/acoustic extension to the IceCube array, specifically intended to detect cosmogenic (GZK) neutrinos with multiple methods simultaneously in order to achieve high confidence in a discovered signal and to measure angular, temporal, and spectral distributions of GZK neutrinos. This work motivated the design, deployment, and operation of the South Pole Acoustic Test Setup (SPATS). The main purpose of SPATS is to measure the acoustic attenuation length, sound speed profile, noise floor, and transient noise sources in situ at the South Pole. We describe the design, performance, and results from SPATS. We measured the sound speed in the fully dense ice between 200 m and 500 m depth to be 3878 ± 12 m/s for pressure waves and 1975.8 ± 8.0 m/s for shear waves. We measured the acoustic amplitude attenuation length to be 316 ± 105 m. We measured the background noise floor to be Gaussian and very stable on all time scales from one second to two years. Finally, we have detected an interesting set of well-reconstructed transient events in over one year of high quality transient data acquisition. We conclude with a discussion of what is next for SPATS and of the prospects for acoustic neutrino detection in ice. Read more (4131kb, PDF) __________________

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Posts: 129165
Date:
 RE: IceCube Permalink Title: The Shadow of the Moon in IceCube Authors: L. Gladstone, for the IceCube Collaboration IceCube is the world's largest neutrino telescope, recently completed at the South Pole. As a proof of pointing accuracy, we look for the image of the Moon as a deficit in down-going cosmic ray muons, using techniques similar to those used in IceCube's astronomical point-source searches. Read more (562kb, PDF) __________________

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Posts: 129165
Date:
 IceCube Neutrino Observatory Permalink Title: The IceCube Neutrino Observatory VI: Neutrino Oscillations, Supernova Searches, Ice Properties Authors: The IceCube Collaboration Atmospheric neutrino oscillations with DeepCore; Supernova detection with IceCube and beyond; Study of South Pole ice transparency with IceCube flashers; Submitted papers to the 32nd International Cosmic Ray Conference, Beijing 2011. Read more (3763kb, PDF) __________________

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Posts: 129165
Date:
 PINGU Permalink Title: Requirements for a New Detector at the South Pole Receiving an Accelerator Neutrino BeamAuthors: Jian Tang, Walter WinterThere are recent considerations to increase the photomultiplier density in the IceCube detector array beyond that of DeepCore, which will lead to a lower detection threshold and a huge fiducial mass for the neutrino detection. This initiative is known as "Phased IceCube Next Generation Upgrade" (PINGU). We discuss the possibility to send a neutrino beam from one of the major accelerator laboratories in the Northern hemisphere to such a detector. Such an experiment would be unique in the sense that it would be the only neutrino beam where the baseline crosses the Earth's core. We study the detector requirements for a beta beam, a neutrino factory beam, and a superbeam, where we consider both the cases of small theta_13 and large theta_13, as suggested by the recent T2K hint. We illustrate that a flavour-clean beta beam best suits the requirements of such a detector, in particular, that PINGU may replace a magic baseline detector for small values of theta_13 -- even in the absence of any energy resolution capability. For large theta_13, however, a single-baseline beta beam experiment cannot compete if it is constrained by the CERN-SPS. For a neutrino factory, because of the missing charge identification possibility in the detector, a very good energy resolution is required. If this can be achieved, especially a low energy neutrino factory, which does not suffer from the tau contamination, may be an interesting option for large theta_13. For the superbeam, where we use the LBNE beam as a reference, electron neutrino flavour identification and statistics are two of the main limitations. Finally, we demonstrate that, at least in principle, neutrino factory and superbeam can measure the density of the Earth's core to the sub-percent level for sin² 2theta_13 larger than 0.01. Read more  (1622kb, PDF) __________________

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Posts: 129165
Date:
 RE: IceCube Permalink Title: Constraints on Enhanced Dark Matter Annihilation from IceCube ResultsAuthors: Ivone F.M. Albuquerque, Leandro J. Beraldo e Silva, Carlos Pérez de los HerosExcesses on electromagnetic fluxes measured by ATIC, and the PAMELA and Fermi-LAT telescopes can be explained by dark matter annihilation in our Galaxy. However, this requires large boosts on the dark matter annihilation rate. There are many possible enhancement mechanisms, such as the Sommerfeld effect or the existence of dark matter clumps in our halo. If such enhancements are taking place, the dark matter annihilation in the core of the Earth should also be enhanced. Here we use IceCube 40 strings results in order to constrain large boosts. These constraints do not depend on the enhancement mechanism. We also determine the boost range that can be probed by the full IceCube telescope. Dark matter models which require annihilation enhancements of 100 or more and that annihilate significantly into neutrinos are excluded as the explanation for these excesses. Read more (651kb, PDF) __________________
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