| 11. |
- Aartsen, M. G., et al.
(author)
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South Pole glacial climate reconstruction from multi-borehole laser particulate stratigraphy
- 2013
-
In: Journal of Glaciology. - 0022-1430 .- 1727-5652. ; 59:218, s. 1117-1128
-
Journal article (peer-reviewed)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.
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| 12. |
- Abbasi, R., et al.
(author)
-
An improved method for measuring muon energy using the truncated mean of dE/dx
- 2013
-
In: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 703, s. 190-198
-
Journal article (peer-reviewed)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.
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| 13. |
- Abbasi, R., et al.
(author)
-
Cosmic ray composition and energy spectrum from 1-30 PeV using the 40-string configuration of IceTop and IceCube
- 2013
-
In: Astroparticle physics. - : Elsevier BV. - 0927-6505 .- 1873-2852. ; 42, s. 15-32
-
Journal article (peer-reviewed)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.
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| 14. |
- Abbasi, R., et al.
(author)
-
Lateral distribution of muons in IceCube cosmic ray events
- 2013
-
In: Physical Review D. - 1550-7998 .- 1550-2368. ; 87:1, s. 012005-
-
Journal article (peer-reviewed)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
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| 15. |
- Abbasi, R., et al.
(author)
-
Search for relativistic magnetic monopoles with IceCube
- 2013
-
In: Physical Review D. - 1550-7998 .- 1550-2368. ; 87:2, s. 022001-
-
Journal article (peer-reviewed)abstract
- We present the first results in the search for relativistic magnetic monopoles with the IceCube detector, a subsurface neutrino telescope located in the South Polar ice cap containing a volume of 1 km(3). This analysis searches data taken on the partially completed detector during 2007 when roughly 0.2 km(3) of ice was instrumented. The lack of candidate events leads to an upper limit on the flux of relativistic magnetic monopoles of Phi(90%C.L.) similar to 3 x 10(-18) cm(-2) sr(-1) s(-1) for beta >= 0.8. This is a factor of 4 improvement over the previous best experimental flux limits up to a Lorentz boost gamma below 10(7). This result is then interpreted for a wide range of mass and kinetic energy values.
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| 16. |
- Abbasi, R., et al.
(author)
-
Searches for high-energy neutrino emission in the galaxy with the combined icecube-amanda detector
- 2013
-
In: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 763:1, s. 33-
-
Journal article (peer-reviewed)abstract
- We report on searches for neutrino sources at energies above 200 GeV in the Northern sky of the Galactic plane, using the data collected by the South Pole neutrino telescope, IceCube, and AMANDA. The Galactic region considered in this work includes the local arm toward the Cygnus region and our closest approach to the Perseus Arm. The searches are based on the data collected between 2007 and 2009. During this time AMANDA was an integrated part of IceCube, which was still under construction and operated with 22 strings (2007-2008) and 40 strings (2008-2009) of optical modules deployed in the ice. By combining the advantages of the larger IceCube detector with the lower energy threshold of the more compact AMANDA detector, we obtain an improved sensitivity at energies below ∼10 TeV with respect to previous searches. The analyses presented here are a scan for point sources within the Galactic plane, a search optimized for multiple and extended sources in the Cygnus region, which might be below the sensitivity of the point source scan, and studies of seven pre-selected neutrino source candidates. For one of them, Cygnus X-3, a time-dependent search for neutrino emission in coincidence with observed radio and X-ray flares has been performed. No evidence of a signal is found, and upper limits are reported for each of the searches. We investigate neutrino spectra proportional to E -2 and E -3 in order to cover the entire range of possible neutrino spectra. The steeply falling E -3 neutrino spectrum can also be used to approximate neutrino energy spectra with energy cutoffs below 50 TeV since these result in a similar energy distribution of events in the detector. For the region of the Galactic plane visible in the Northern sky, the 90% confidence level muon neutrino flux upper limits are in the range E 3 dN/dE ∼ 5.4-19.5 × 10-11 TeV2 cm-2 s-1 for point-like neutrino sources in the energy region [180.0 GeV-20.5 TeV]. These represent the most stringent upper limits for soft-spectra neutrino sources within the Galaxy reported to date.
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| 17. |
- Scott, P., et al.
(author)
-
Use of event-level neutrino telescope data in global fits for theories of new physics
- 2012
-
In: Journal of Cosmology and Astroparticle Physics. - : IOP Publishing. - 1475-7516. ; :11, s. 057-
-
Journal article (peer-reviewed)abstract
- We present a fast likelihood method for including event-level neutrino telescope data in parameter explorations of theories for new physics, and announce its public release as part of DarkSUSY 5.0.6. Our construction includes both angular and spectral information about neutrino events, as well as their total number. We also present a corresponding measure for simple model exclusion, which can be used for single models without reference to the rest of a parameter space. We perform a number of supersymmetric parameter scans with IceCube data to illustrate the utility of the method: example global fits and a signal recovery in the constrained minimal supersymmetric standard model (CMSSM), and a model exclusion exercise in a 7-parameter phenomenological version of the MSSM. The final IceCube detector con figuration will probe almost the entire focus-point region of the CMSSM, as well as a number of MSSM-7 models that will not otherwise be accessible to e. g. direct detection. Our method accurately recovers the mock signal, and provides tight constraints on model parameters and derived quantities. We show that the inclusion of spectral information significantly improves the accuracy of the recovery, providing motivation for its use in future IceCube analyses.
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| 18. |
- Abbasi, R., et al.
(author)
-
Calibration and characterization of the IceCube photomultiplier tube
- 2010
-
In: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 618:1-3, s. 139-152
-
Journal article (peer-reviewed)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.
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| 19. |
- Abbasi, R., et al.
(author)
-
First search for extremely high energy cosmogenic neutrinos with the IceCube Neutrino Observatory
- 2010
-
In: Physical review. D, Particles, fields, gravitation, and cosmology. - 1550-7998. ; 82:7, s. 072003-
-
Journal article (peer-reviewed)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.
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| 20. |
- Abbasi, R., et al.
(author)
-
Limits on a muon flux from Kaluza-Klein dark matter annihilations in the Sun from the IceCube 22-string detector
- 2010
-
In: Physical Review D. - 1550-7998 .- 1550-2368. ; 81:5, s. 057101-
-
Journal article (peer-reviewed)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.
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