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• 1. Abbasi, R.
Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
Limits on a muon flux from Kaluza-Klein dark matter annihilations in the Sun from the IceCube 22-string detector2010In: Physical Review D, ISSN 1550-7998, E-ISSN 1550-2368, Vol. 81, no 5, p. Article ID: 057101-Article in journal (Refereed)

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.

• 2. Abbasi, R.
Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
SEARCH FOR MUON NEUTRINOS FROM GAMMA-RAY BURSTS WITH THE IceCube NEUTRINO TELESCOPE2010In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 710, no 1, p. 346-359Article in journal (Refereed)

We present the results of searches for high-energy muon neutrinos from 41 gamma-ray bursts (GRBs) in the northern sky with the IceCube detector in its 22 string configuration active in 2007/2008. The searches cover both the prompt and a possible precursor emission as well as a model-independent, wide time window of -1 hr to + 3 hr around each GRB. In contrast to previous searches with a large GRB population, we do not utilize a standard Waxman-Bahcall GRB flux for the prompt emission but calculate individual neutrino spectra for all 41 GRBs from the burst parameters measured by satellites. For all of the three time windows, the best estimate for the number of signal events is zero. Therefore, we place 90% CL upper limits on the fluence from the prompt phase of 3.7 x 10(-3) erg cm(-2) (72 TeV-6.5 PeV) and on the fluence from the precursor phase of 2.3 x 10(-3) erg cm(-2) (2.2-55 TeV), where the quoted energy ranges contain 90% of the expected signal events in the detector. The 90% CL upper limit for the wide time window is 2.7 x 10(-3) erg cm(-2) (3 TeV-2.8 PeV) assuming an E-2 flux.

• 3. Abbasi, R.
University of Kalmar, School of Pure and Applied Natural Sciences.
SEARCH FOR HIGH-ENERGY MUON NEUTRINOS FROM THE "NAKED-EYE" GRB 080319B WITH THE IceCube NEUTRINO TELESCOPE2009In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 701, no 2, p. 1721-1731Article in journal (Refereed)

We report on a search with the IceCube detector for high-energy muon neutrinos from GRB 080319B, one of the brightest gamma-ray bursts (GRBs) ever observed. The fireball model predicts that a mean of 0.1 events should be detected by IceCube for a bulk Lorentz boost of the jet of 300. In both the direct on-time window of 66 s and an extended window of about 300 s around the GRB, no excess was found above background. The 90% CL upper limit on the number of track-like events from the GRB is 2.7, corresponding to a muon neutrino fluence limit of 9.5 x 10(-3) erg cm(-2) in the energy range between 120 TeV and 2.2 PeV, which contains 90% of the expected events.

• 4. Abbasi, R.
University of Kalmar, School of Pure and Applied Natural Sciences.
Extending the Search for Neutrino Point Sources with IceCube above the Horizon2009In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 103, no 22, p. Article ID: 221102-Article in journal (Refereed)

Point source searches with the IceCube neutrino telescope have been restricted to one hemisphere, due to the exclusive selection of upward going events as a way of rejecting the atmospheric muon background. We show that the region above the horizon can be included by suppressing the background through energy-sensitive cuts. This improves the sensitivity above PeV energies, previously not accessible for declinations of more than a few degrees below the horizon due to the absorption of neutrinos in Earth. We present results based on data collected with 22 strings of IceCube, extending its field of view and energy reach for point source searches. No significant excess above the atmospheric background is observed in a sky scan and in tests of source candidates. Upper limits are reported, which for the first time cover point sources in the southern sky up to EeV energies.

• 5. Abbasi, R.
Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
Calibration and characterization of the IceCube photomultiplier tube2010In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 618, no 1-3, p. 139-152Article in journal (Refereed)

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.

• 6. Abbasi, R.
Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
Measurement of sound speed vs. depth in South Pole ice for neutrino astronomy2010In: Astroparticle physics, ISSN 0927-6505, E-ISSN 1873-2852, Vol. 33, no 5-6, p. 277-286Article in journal (Refereed)

We have measured the speed of both pressure waves and shear waves as a function of depth between 80 and 500 m depth in South Pole ice with better than 1% precision. The measurements were made using the South Pole Acoustic Test Setup (SPATS), an array of transmitters and sensors deployed in the ice at the South Pole in order to measure the acoustic properties relevant to acoustic detection of astrophysical neutrinos. The transmitters and sensors use piezoceramics operating at similar to 5-25 kHz. Between 200 m and 500 m depth, the measured profile is consistent with zero variation of the sound speed with depth, resulting in zero refraction, for both pressure and shear waves. We also performed a complementary study featuring an explosive signal propagating vertically from 50 to 2250 m depth, from which we determined a value for the pressure wave speed consistent with that determined for shallower depths, higher frequencies, and horizontal propagation with the SPATS sensors. The sound speed profile presented here can be used to achieve good acoustic source position and emission time reconstruction in general, and neutrino direction and energy reconstruction in particular. The reconstructed quantities could also help separate neutrino signals from background. (C) 2010 Elsevier B.V. All rights reserved.

• 7. Abbasi, R.
University of Kalmar, School of Pure and Applied Natural Sciences.
First Neutrino Point-Source Results from the 22 String Icecube Detector2009In: The Astrophysical Journal Letters, ISSN 2041-8205, Vol. 701, no 1, p. L47-L51Article in journal (Refereed)

We present new results of searches for neutrino point sources in the northern sky, using data recorded in 2007-2008 with 22 strings of the IceCube detector (approximately one-fourth of the planned total) and 275.7 days of live time. The final sample of 5114 neutrino candidate events agrees well with the expected background of atmospheric muon neutrinos and a small component of atmospheric muons. No evidence of a point source is found, with the most significant excess of events in the sky at 2.2Ïƒ after accounting for all trials. The average upper limit over the northern sky for point sources of muon-neutrinos with E â€“2 spectrum is ##IMG## [http://ej.iop.org/images/1538-4357/701/1/L47/apjl318527ieqn1.gif] $E^2\,Φ _ν _μ < 1.4 \,\,\times\,\, 10^-11\; \mathrmTeV\;cm^-2\;\mathrms^-1$ , in the energy range from 3Â TeV to 3Â PeV, improving the previous best average upper limit by the AMANDA-II detector by a factor of 2.

• 8. Abbasi, R.
University of Kalmar, School of Pure and Applied Natural Sciences.
Limits on a Muon Flux from Neutralino Annihilations in the Sun with the IceCube 22-String Detector2009In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 102, no 20, p. Article ID: 201302-Article in journal (Refereed)

A search for muon neutrinos from neutralino annihilations in the Sun has been performed with the IceCube 22-string 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 neutralinos in the Sun and converted to limits on the weakly interacting massive particle (WIMP) proton cross sections for WIMP masses in the range 250-5000 GeV. These results are the most stringent limits to date on neutralino annihilation in the Sun.

• 9. Abbasi, R.
University of Kalmar, School of Pure and Applied Natural Sciences.
Determination of the atmospheric neutrino flux and searches for new physics with AMANDA-II2009In: Physical Review D, ISSN 1550-7998, E-ISSN 1550-2368, Vol. 79, no 10, p. Article ID: 102005-Article in journal (Refereed)

The AMANDA-II detector, operating since 2000 in the deep ice at the geographic South Pole, has accumulated a large sample of atmospheric muon neutrinos in the 100 GeV to 10 TeV energy range. The zenith angle and energy distribution of these events can be used to search for various phenomenological signatures of quantum gravity in the neutrino sector, such as violation of Lorentz invariance or quantum decoherence. Analyzing a set of 5511 candidate neutrino events collected during 1387 days of livetime from 2000 to 2006, we find no evidence for such effects and set upper limits on violation of Lorentz invariance and quantum decoherence parameters using a maximum likelihood method. Given the absence of evidence for new flavor-changing physics, we use the same methodology to determine the conventional atmospheric muon neutrino flux above 100 GeV.

• 10. Abbasi, R.
University of Kalmar, School of Pure and Applied Natural Sciences.
Search for point sources of high energy neutrinos with final data from AMANDA-II2009In: Physical Review D, ISSN 1550-7998, E-ISSN 1550-2368, Vol. 79, no 6, p. Article ID: 062001-Article in journal (Refereed)

We present a search for point sources of high energy neutrinos using 3.8 yr of data recorded by AMANDA-II during 2000-2006. After reconstructing muon tracks and applying selection criteria designed to optimally retain neutrino-induced events originating in the northern sky, we arrive at a sample of 6595 candidate events, predominantly from atmospheric neutrinos with primary energy 100 GeV to 8 TeV. Our search of this sample reveals no indications of a neutrino point source. We place the most stringent limits to date on E(-2) neutrino fluxes from points in the northern sky, with an average upper limit of E(2)Phi(nu mu)+nu(tau)<= 5.2x10(-11) TeV cm(-2) s(-1) on the sum of nu(mu) and nu(tau) fluxes, assumed equal, over the energy range from 1.9 TeV to 2.5 PeV.

• 11. Abbasi, R.
University of Kalmar, School of Pure and Applied Natural Sciences.
Solar Energetic Particle Spectrum on 2006 December 13 Determined by IceTop2008In: The Astrophysical Journal Letters, Vol. 689, no 1, p. L65-L68Article in journal (Refereed)

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.

• 12. Abbasi, R.
University of Kalmar, School of Pure and Applied Natural Sciences.
The IceCube data acquisition system: Signal capture, digitization, and timestamping2009In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 601, no 3, p. 294-316Article in journal (Refereed)

IceCube is a km-scale neutrino observatory under construction at the South Pole with sensors both in the deep ice (InIce) and on the surface (IceTop). The sensors, called Digital Optical Modules (DOMs). detect, digitize and timestamp the signals from optical Cherenkov-radiation photons. The DOM Main Board (MB) data acquisition subsystem is connected to the central DAQ in the IceCube Laboratory (ICL) by a single twisted copper wire-pair and transmits packetized data on demand. Time calibration is maintained throughout the array by regular transmission to the DOMs of precisely timed analog signals, synchronized to a central GPS-disciplined clock. The design goals and consequent features, functional capabilities, and initial performance of the DOM MB, and the operation of a combined array of DOMs as a system, are described here. Experience with the first InIce strings and the IceTop stations indicates that the system design and performance goals have been achieved. (c) 2009 Elsevier B.V. All rights reserved.

• 13. Ahrens, J.
University of Kalmar, School of Pure and Applied Natural Sciences. University of Kalmar, School of Pure and Applied Natural Sciences. University of Kalmar, School of Pure and Applied Natural Sciences.
Measurement of the cosmic ray composition at the knee with the SPASE-2/AMANDA-B10 detectors2004In: Astroparticle physics, ISSN 0927-6505, E-ISSN 1873-2852, Vol. 21, no 6, p. 565-581Article in journal (Refereed)

The mass composition of high-energy cosmic rays at energies above 1015 eV can provide crucial information for the understanding of their origin. Air showers were measured simultaneously with the SPASE-2 air shower array and the AMANDA-B10 Cherenkov telescope at the South Pole. This combination has the advantage to sample almost all high-energy shower muons and is thus a new approach to the determination of the cosmic ray composition. The change in the cosmic ray mass composition was measured versus existing data from direct measurements at low energies. Our data show an increase of the mean log atomic mass 〈lnA〉 by about 0.8 between 500 TeV and 5 PeV. This trend of an increasing mass through the "knee" region is robust against a variety of systematic effects. © 2004 Elsevier B.V. All rights reserved.

• 14. Ahrens, J.
University of Kalmar, School of Pure and Applied Natural Sciences. University of Kalmar, School of Pure and Applied Natural Sciences. University of Kalmar, School of Pure and Applied Natural Sciences.
Observation of high energy atmospheric neutrinos with the Antarctic muon and neutrino detector array2002In: Physical Review D, ISSN 1550-7998, E-ISSN 1550-2368, Vol. 66, no 1, p. 120051-1200520Article in journal (Refereed)

The Antarctic muon and neutrino detector array (AMANDA) began collecting data with ten strings in 1997. Results from the first year of operation are presented. Neutrinos coming through the Earth from the Northern Hemisphere are identified by secondary muons moving upward through the array. Cosmic rays in the atmosphere generate a background of downward moving muons, which are about 106 times more abundant than the upward moving muons. Over 130 days of exposure, we observed a total of about 300 neutrino events. In the same period, a background of 1.05 × 109 cosmic ray muon events was recorded. The observed neutrino flux is consistent with atmospheric neutrino predictions. Monte Carlo simulations indicate that 90% of these events lie in the energy range 66 GeV to 3.4 TeV. The observation of atmospheric neutrinos consistent with expectations establishes AMANDA-B10 as a working neutrino telescope.

• 15. Ahrens, J.
University of Kalmar, School of Pure and Applied Natural Sciences. University of Kalmar, School of Pure and Applied Natural Sciences. University of Kalmar, School of Pure and Applied Natural Sciences.
Limits to the muon flux from WIMP annihilation in the center of the Earth with the AMANDA detector2002In: Physical Review D, ISSN 1550-7998, E-ISSN 1550-2368, Vol. 66, no 3, p. 032006-Article in journal (Refereed)

A search for nearly vertical up-going muon-neutrinos from neutralino annihilations in the center of the Earth has been performed with the AMANDA-B10 neutrino detector. The data collected in 130.1 days of live time in 1997, ∼10 9 events, have been analyzed for this search. No excess over the expected atmospheric neutrino background has been observed. An upper limit at 90% confidence level has been obtained on the annihilation rate of neutralinos in the center of the Earth, as well as the corresponding muon flux limit, both as a function of the neutralino mass in the range 100 GeV-5000 GeV. © 2002 The American Physical Society.

• 16. Ahrens, J.
University of Kalmar, School of Pure and Applied Natural Sciences. University of Kalmar, School of Pure and Applied Natural Sciences. University of Kalmar, School of Pure and Applied Natural Sciences.
Search for point sources of high-energy neutrinos with AMANDA2003In: Astrophysical Journal Letters, ISSN 2041-8205, Vol. 583, no 2 I, p. 1040-1057Article in journal (Refereed)

This paper describes the search for astronomical sources of high-energy neutrinos using the AMANDA-B10 detector, an array of 302 photomultiplier tubes used for the detection of Cerenkov light from upward-traveling neutrino-induced muons, buried deep in ice at the South Pole. The absolute pointing accuracy and angular resolution were studied by using coincident events between the AMANDA detector and two independent telescopes on the surface, the GASP air Cerenkov telescope and the SPASE extensive air shower array. Using data collected from 1997 April to October (130.1 days of live time), a general survey of the northern hemisphere revealed no statistically significant excess of events from any direction. The sensitivity for a flux of muon neutrinos is based on the effective detection area for through-going muons. Averaged over the northern sky, the effective detection area exceeds 10,000 m2 for E μ ≈ 10 TeV. Neutrinos generated in the atmosphere by cosmic-ray interactions were used to verify the predicted performance of the detector. For a source with a differential energy spectrum proportional to Eν -2 and declination larger than +40°, we obtain E2(dNν/dE) ≤ 10-6 GeV cm-2 s-1 for an energy threshold of 10 GeV.

• 17. Ahrens, J.
University of Kalmar, School of Pure and Applied Natural Sciences. University of Kalmar, School of Pure and Applied Natural Sciences. University of Kalmar, School of Pure and Applied Natural Sciences.
Search for neutrino-induced cascades with the AMANDA detector2003In: Physical Review D, ISSN 1550-7998, E-ISSN 1550-2368, Vol. 67, no 1, p. 012003-Article in journal (Refereed)

We report on a search for electromagnetic and/or hadronic showers (cascades) induced by a diffuse flux of neutrinos with energies between 5 TeV and 300 TeV from extraterrestrial sources. Cascades may be produced by matter interactions of all flavors of neutrinos, and contained cascades have better energy resolution and afford better background rejection than throughgoing νμ-induced muons. Data taken in 1997 with the AMANDA detector were searched for events with a high-energy cascadelike signature. The observed events are consistent with expected backgrounds from atmospheric neutrinos and catastrophic energy losses from atmospheric muons. Effective volumes for all flavors of neutrinos, which allow the calculation of limits for any neutrino flux model, are presented. The limit on cascades from a diffuse flux of νe+ νμ + ντ+ ν̄e + ν̄μ+ ν̄τ is E2(dΦ/dE)&lt;9.8×10-6 GeV cm-2 s-1 sr-1, assuming a neutrino flavor flux ratio of 1:1:1 at the detector. The limit on cascades from a diffuse flux of νe+ν̄e is E2(dΦ/dE)&lt;6. 5×10-6 GeV cm-2 s-1 sr-1, independent of the assumed neutrino flavor flux ratio. © 2003 The American Physical Society.

• 18. Ahrens, J.
University of Kalmar, School of Pure and Applied Natural Sciences. University of Kalmar, School of Pure and Applied Natural Sciences. University of Kalmar, School of Pure and Applied Natural Sciences.
Limits on diffuse fluxes of high energy extraterrestrial neutrinos with the AMANDA-B10 detector2003In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 90, no 25, p. 2511011-2511015Article in journal (Refereed)

A report on the limits, which could be placed on diffuse fluxes of high energy extraterrestrial neutrinos, was presented. The incorporation of neutrino oscillations was necessary for interpreting the limits in terms of the flux from a cosmological distributions of sources. The energetic accelerated environments were presented as the sources of high energy extraterrestrial neutrinos.

• 19. Ahrens, J.
University of Kalmar, School of Pure and Applied Natural Sciences. University of Kalmar, School of Pure and Applied Natural Sciences. University of Kalmar, School of Pure and Applied Natural Sciences.
Search for Extraterrestrial Point Sources of Neutrinos with AMANDA-II2004In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 92, no 7, p. 711021-711025Article in journal (Refereed)

The results of a search for point sources of high energy neutrinos in the northern hemisphere were presented using AMANDA-II data collected in the year 2000. The results included the flux limits on several active-galactic-nuclei blazars, microquasars, magnetars, and other candidate neutrino sources. A search for excesses above a random background of cosmic ray induced atmospheric neutrinos and misreconstructed downgoing cosmic-rays muons, which revealed no statistically significant neutrino point sources was also presented. It was shown that AMANDA-II had achieved the sensitivity required to probe known TeV γ-ray sources such as the blazar Markarian 501 in its 1997 flaring state at a level where neutrino and γ-ray fluxes were equal.

• 20. Ahrens, J.
University of Kalmar, School of Pure and Applied Natural Sciences. University of Kalmar, School of Pure and Applied Natural Sciences. University of Kalmar, School of Pure and Applied Natural Sciences.
Results from the Antarctic muon and nuetrino detector array2003In: Nuclear physics B, Proceedings supplements, ISSN 0920-5632, E-ISSN 1873-3832, Vol. 118, p. 371-379Article in journal (Refereed)

We show new results from both the older and newer incarnations of AMANDA (AMANDA-B10 and AMANDA-II, respectively). These results demonstrate that AMANDA is a functioning, multipurpose detector with significant physics and astrophysics reach. They include a new higher-statistics measurement of the atmospheric muon neutrino flux and preliminary results from searches for a variety of sources of ultrahigh energy neutrinos: generic point sources, gamma-ray bursters and diffuse sources producing muons in the detector, and diffuse sources producing electromagnetic or hadronic showers in or near the detector.

• 21. Ahrens, J.
University of Kalmar, School of Pure and Applied Natural Sciences. University of Kalmar, School of Pure and Applied Natural Sciences. University of Kalmar, School of Pure and Applied Natural Sciences.
Results from the AMANDA telescope2003In: Nuclear Physics A, ISSN 0375-9474, E-ISSN 1873-1554, Vol. 721, p. C545-C548Article in journal (Refereed)

We present results from the AMANDA high energy neutrino telescope located at the South Pole. They include measurements of the atmospheric neutrino flux, search for UHE point sources, and diffuse sources producing electromagnetic/hadronic showers at the detector or close to it.

• 22. Ahrens, J.
University of Kalmar, School of Pure and Applied Natural Sciences. University of Kalmar, School of Pure and Applied Natural Sciences. University of Kalmar, School of Pure and Applied Natural Sciences.
Physics and operation of the AMANDA-II high energy neutrino telescope2002In: Proceedings of the SPIE - The International Society for Optical Engineering 2003, Institution of Electrical Engineers (IEE), 2002, p. 79-91Conference paper (Refereed)

This paper briefly describes the principle of operation and science goals of the AMANDA high energy neutrino telescope located at the South Pole, Antarctica. Results from an earlier phase of the telescope, called AMANDA-B10, demonstrate both reliable operation and the broad astrophysical reach of this device, which includes searches for a variety of sources of ultrahigh energy neutrinos: generic point sources, Gamma-Ray Bursts and diffuse sources. The predicted sensitivity and angular resolution of the telescope were confirmed by studies of atmospheric muon and neutrino backgrounds. We also report on the status of the analysis from AMANDA-II, a larger version with far greater capabilities. At this stage of analysis, details of the ice properties and other systematic uncertainties of the AMANDA-II telescope are under study, but we have made progress toward critical science objectives. In particular, we focus on the search for continuous emission from astrophysical point sources and the search for correlated neutrino emission from Gamma Ray Bursts detected by BATSE before decommissioning in May 2000. During the next two years, we expect to exploit the full potential of AMANDA-II with the installation of a new data acquisition system that records full waveforms from the in-ice optical sensors.

• 23. Ahrens, J.
University of Kalmar, School of Pure and Applied Natural Sciences. University of Kalmar, School of Pure and Applied Natural Sciences. University of Kalmar, School of Pure and Applied Natural Sciences.
Muon track reconstruction and data selection techniques in AMANDA2004In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 524, no 1-3, p. 169-194Article in journal (Refereed)

The Antarctic Muon And Neutrino Detector Array (AMANDA) is a high-energy neutrino telescope operating at the geographic South Pole. It is a lattice of photo-multiplier tubes buried deep in the polar ice between 1500 and 2000 m. The primary goal of this detector is to discover astrophysical sources of high-energy neutrinos. A high-energy muon neutrino coming through the earth from the Northern Hemisphere can be identified by the secondary muon moving upward through the detector. The muon tracks are reconstructed with a maximum likelihood method. It models the arrival times and amplitudes of Cherenkov photons registered by the photo-multipliers. This paper describes the different methods of reconstruction, which have been successfully implemented within AMANDA. Strategies for optimizing the reconstruction performance and rejecting background are presented. For a typical analysis procedure the direction of tracks are reconstructed with about 2° accuracy. © 2004 Elsevier B.V. All rights reserved.

• 24. AMANDA Collaboration, -
University of Kalmar, School of Pure and Applied Natural Sciences.
Flux limits on ultra high energy neutrinos with AMANDA-B102005In: Astroparticle physics, ISSN 0927-6505, E-ISSN 1873-2852, Vol. 22, no 5-6, p. 339-353Article in journal (Refereed)

Data taken during 1997 with the AMANDA-B10 detector are searched for a diffuse flux of neutrinos of all flavors with energies above 10(16) eV. At these energies the Earth is opaque to neutrinos, and thus neutrino induced events are concentrated at the horizon. The background are large muon bundles from down-going atmospheric air shower events. No excess events above the background expectation are observed and a neutrino flux following E-2, with an equal mix of all flavors, is limited to E(2)Phi(10(15) eV < E < 3 x 10(18) eV) less than or equal to 0.99 x 10(-6) GeV cm(-2) s(-1) sr(-1) at 90% confidence level. This is the most restrictive experimental bound placed by any neutrino detector at these energies. Bounds to specific extraterrestrial neutrino flux predictions are also presented.

• 25. AMANDA Collaboration, -
University of Kalmar, School of Pure and Applied Natural Sciences.
Limits to the muon flux from neutralino annihilations at the Center of the Earth with AMANDA2006In: Astroparticle physics, ISSN 0927-6505, E-ISSN 1873-2852, Vol. 26, no 2, p. 129-139Article in journal (Refereed)

A search has been performed for nearly vertically upgoing neutrino-induced muons with the Antarctic Muon And Neutrino DetectorArray (AMANDA), using data taken over the three year period 1997–99. No excess above the expected atmospheric neutrino backgroundhas been found. Upper limits at 90% confidence level have been set on the annihilation rate of neutralinos at the center ofthe Earth, as well as on the muon flux at AMANDA induced by neutrinos created by the annihilation products.

• 26. AMANDA Collaboration, -
University of Kalmar, School of Pure and Applied Natural Sciences.
Limits to the muon flux from neutralino annihilations in the Sun with the AMANDA detector2006In: Astroparticle physics, ISSN 0927-6505, E-ISSN 1873-2852, Vol. 24, no 6, p. 459-466Article in journal (Refereed)

A search for an excess of muon-neutrinos from neutralino annihilations in the Sun has been performed with the AMANDA-II neutrino detector using data collected in 143.7 days of live-time in 2001. No excess over the expected atmospheric neutrino background has been observed. An upper limit at 90% confidence level has been obtained on the annihilation rate of captured neutralinos in the Sun, as well as the corresponding muon flux limit at the Earth, both as functions of the neutralino mass in the range 100-5000 GeV.

• 27. Amanda Collaboration, -
University of Kalmar, School of Pure and Applied Natural Sciences.
Optical Properties of Deep Glacial Ice at the South Pole2006In: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 111, no D13, p. D13203-Article in journal (Refereed)

We have remotely mapped optical scattering and absorption in glacial ice at the South Pole for wavelengths between 313 and 560 nm and depths between 1100 and 2350 m. We used pulsed and continuous light sources embedded with the AMANDA neutrino telescope, an array of more than six hundred photomultiplier tubes buried deep in the ice. At depths greater than 1300 m, both the scattering coefficient and absorptivity follow vertical variations in concentration of dust impurities, which are seen in ice cores from other Antarctic sites and which track climatological changes. The scattering coefficient varies by a factor of seven, and absorptivity (for wavelengths less than ∼450 nm) varies by a factor of three in the depth range between 1300 and 2300 m, where four dust peaks due to stadials in the late Pleistocene have been identified. In our absorption data, we also identify a broad peak due to the Last Glacial Maximum around 1300 m. In the scattering data, this peak is partially masked by scattering on residual air bubbles, whose contribution dominates the scattering coefficient in shallower ice but vanishes at ∼1350 m where all bubbles have converted to nonscattering air hydrates. The wavelength dependence of scattering by dust is described by a power law with exponent −0.90 ± 0.03, independent of depth. The wavelength dependence of absorptivity in the studied wavelength range is described by the sum of two components: a power law due to absorption by dust, with exponent −1.08 ± 0.01 and a normalization proportional to dust concentration that varies with depth; and a rising exponential due to intrinsic ice absorption which dominates at wavelengths greater than ∼500 nm.

• 28. AMANDA Collaboration, -
University of Kalmar, School of Pure and Applied Natural Sciences.
Search for extraterrestrial point sources of high energy neutrinos with AMANDA-II using data collected in 2000-20022005In: Physical Review D. Particles and fields, ISSN 0556-2821, E-ISSN 1089-4918, Vol. 71, no 7, p. 077102-Article in journal (Refereed)

The results of a search for point sources of high energy neutrinos in the northern hemisphere using data collected by AMANDA-II in the years 2000, 2001, and 2002 are presented. In particular, a comparison with the single-year result previously published shows that the sensitivity was improved by a factor of 2.2. The muon neutrino flux upper limits on selected candidate sources, corresponding to an E-nu(-2) neutrino energy spectrum, are included. Sky grids were used to search for possible excesses above the background of cosmic ray induced atmospheric neutrinos. This search reveals no statistically significant excess for the three years considered.

• 29. AMANDA Collaboration, -
University of Kalmar, School of Pure and Applied Natural Sciences.
The ICECUBE prototype string in AMANDA2006In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 556, no 1, p. 169-181Article in journal (Refereed)

The Antarctic Muon And Neutrino Detector Array (AMANDA) is a high-energy neutrino telescope. It is a lattice of optical modules (OM) installed in the clear ice below the South Pole Station. Each OM contains a photomultiplier tube (PMT) that detects photons of Cherenkov light generated in the ice by muons and electrons. ICECUBE is a cubic-kilometer-sized expansion of AMANDA currently being built at the South Pole. In ICECUBE the PMT signals are digitized already in the optical modules and transmitted to the surface. A prototype string of 41 OMs equipped with this new all-digital technology was deployed in the AMANDA array in the year 2000. In this paper we describe the technology and demonstrate that this string serves as a proof of concept for the ICECUBE array. Our investigations show that the OM timing accuracy is 5 ns. Atmospheric muons are detected in excellent agreement with expectations with respect to both angular distribution and absolute rate.

• 30. IceCube Collaboration, -
University of Kalmar, School of Pure and Applied Natural Sciences.
Detection of Atmospheric Muon Neutrinos with the IceCube 9-String Detector2007In: Physical Review D. Particles and fields, ISSN 0556-2821, E-ISSN 1089-4918, Vol. 76, no 2, p. 027101-Article in journal (Refereed)

The IceCube neutrino detector is a cubic kilometer TeV to PeV neutrino detector under construction at the geographic South Pole. The dominant population of neutrinos detected in IceCube is due to meson decay in cosmic-ray air showers. These atmospheric neutrinos are relatively well understood and serve as a calibration and verification tool for the new detector. In 2006, the detector was approximately 10% completed, and we report on data acquired from the detector in this configuration. We observe an atmospheric neutrino signal consistent with expectations, demonstrating that the IceCube detector is capable of identifying neutrino events. In the first 137.4 days of live time, 234 neutrino candidates were selected with an expectation of 211 +/- 76.1(syst)+/- 14.5(stat) events from atmospheric neutrinos.

• 31. IceCube Collaboration, -
University of Kalmar, School of Pure and Applied Natural Sciences.
First year performance of the IceCube neutrino telescope2006In: Astroparticle physics, ISSN 0927-6505, E-ISSN 1873-2852, Vol. 26, no 3, p. 155-173Article in journal (Refereed)

The first sensors of the IceCube neutrino observatory were deployed at the South Pole during the austral summer of 2004-2005 and have been producing data since February 2005. One string of 60 sensors buried in the ice and a surface array of eight ice Cherenkov tanks took data until December 2005 when deployment of the next set of strings and tanks began. We have analyzed these data, demonstrating that the performance of the system meets or exceeds design requirements. Times are determined across the whole array to a relative precision of better than 3 ns, allowing reconstruction of muon tracks and light bursts in the ice, of air-showers in the surface array and of events seen in coincidence by surface and deep-ice detectors separated by up to 2.5 km.

• 32. IceCube Collaboration, -
University of Kalmar, School of Pure and Applied Natural Sciences.
Five Years of Searches for Point Sources of Astrophysical Neutrinos with the AMANDA-II Neutrino Telescope2007In: Physical Review D. Particles and fields, ISSN 0556-2821, E-ISSN 1089-4918, Vol. 75, no 10, p. 102001-Article in journal (Refereed)

We report the results of a five-year survey of the northern sky to search for point sources of high energy neutrinos. The search was performed on the data collected with the AMANDA-II neutrino telescope in the years 2000 to 2004, with a live time of 1001 days. The sample of selected events consists of 4282 upward going muon tracks with high reconstruction quality and an energy larger than about 100 GeV. We found no indication of point sources of neutrinos and set 90% confidence level flux upper limits for an all-sky search and also for a catalog of 32 selected sources. For the all-sky search, our average (over declination and right ascension) experimentally observed upper limit Phi(0)=(E/1 TeV)(gamma)center dot d Phi/dE to a point source flux of muon and tau neutrino (detected as muons arising from taus) is Phi(nu mu)+nu(0)(mu)+Phi(nu tau)+nu(0)(tau)=11.1x 10(-11) TeV-1 cm(-2) s(-1), in the energy range between 1.6 TeV and 2.5 PeV for a flavor ratio Phi(nu mu)+nu(0)(mu)/Phi(nu tau)+nu(0)(tau)=1 and assuming a spectral index gamma=2. It should be noticed that this is the first time we set upper limits to the flux of muon and tau neutrinos. In previous papers we provided muon neutrino upper limits only neglecting the sensitivity to a signal from tau neutrinos, which improves the limits by 10% to 16%. The value of the average upper limit presented in this work corresponds to twice the limit on the muon neutrino flux Phi(nu mu)+nu(0)(mu)=5.5x10(-11) TeV-1 cm(-2) s(-1). A stacking analysis for preselected active galactic nuclei and a search based on the angular separation of the events were also performed. We report the most stringent flux upper limits to date, including the results of a detailed assessment of systematic uncertainties.

• 33. IceCube Collaboration, -
University of Kalmar, School of Pure and Applied Natural Sciences.
Limits on the High-Energy Gamma and Neutrino Fluxes from the SGR 1806-20 Giant Flare of 27 December 2004 with the AMANDA-II Detector2006In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 97, no 22, p. 221101-Article in journal (Refereed)

On 27 December 2004, a giant gamma flare from the Soft Gamma-Ray Repeater 1806-20 saturated many satellite gamma-ray detectors, being the brightest transient event ever observed in the Galaxy. AMANDA-II was used to search for down-going muons indicative of high-energy gammas and/or neutrinos from this object. The data revealed no significant signal, so upper limits (at 90% C.L.) on the normalization constant were set: 0.05(0.5) TeV-1 m(-2) s(-1) for gamma=-1.47 (-2) in the gamma flux and 0.4(6.1) TeV-1 m(-2) s(-1) for gamma=-1.47 (-2) in the high-energy neutrino flux.

• 34. IceCube Collaboration, -
University of Kalmar, School of Pure and Applied Natural Sciences.
Multiyear Search for a Diffuse Flux of Muon Neutrinos with AMANDA-II2007In: Physical Review D. Particles and fields, ISSN 0556-2821, E-ISSN 1089-4918, Vol. 76, no 4, p. 042008-Article in journal (Refereed)

A search for TeV-PeV muon neutrinos from unresolved sources was performed on AMANDA-II data collected between 2000 and 2003 with an equivalent live time of 807 days. This diffuse analysis sought to find an extraterrestrial neutrino flux from sources with nonthermal components. The signal is expected to have a harder spectrum than the atmospheric muon and neutrino backgrounds. Since no excess of events was seen in the data over the expected background, an upper limit of E-2 Phi(90%C.L.)< 7.4x10(-8) GeV cm(-2) s(-1) sr(-1) is placed on the diffuse flux of muon neutrinos with a Phi proportional to E-2 spectrum in the energy range 16 TeV to 2.5 PeV. This is currently the most sensitive Phi proportional to E-2 diffuse astrophysical neutrino limit. We also set upper limits for astrophysical and prompt neutrino models, all of which have spectra different from Phi proportional to E-2.

• 35. IceCube Collaboration, -
University of Kalmar, School of Pure and Applied Natural Sciences.
On the selection of AGN neutrino source candidates for a source stacking analysis with neutrino telescopes2006In: Astroparticle physics, ISSN 0927-6505, E-ISSN 1873-2852, Vol. 26, no 4-5, p. 282-300Article in journal (Refereed)

The sensitivity of a search for sources of TeV neutrinos can be improved by grouping potential sources together into generic classes in a procedure that is known as source stacking. In this paper, we define catalogs of Active Galactic Nuclei (AGN) and use them to perform a source stacking analysis. The grouping of AGN into classes is done in two steps: first, AGN classes are defined, then, sources to be stacked are selected assuming that a potential neutrino flux is linearly correlated with the photon luminosity in a certain energy band (radio, IR, optical, keV, GeV, TeV). Lacking any secure detailed knowledge on neutrino production in AGN, this correlation is motivated by hadronic AGN models, as briefly reviewed in this paper.The source stacking search for neutrinos from generic AGN classes is illustrated using the data collected by the AMANDA-II highenergy neutrino detector during the year 2000. No significant excess for any of the suggested groups was found. (c) 2006 Elsevier B.V. All rights reserved.

• 36. IceCube Collaboration, -
University of Kalmar, School of Pure and Applied Natural Sciences.
Search for Neutrino-Induced Cascades From Gamma-Ray Bursts with AMANDA2007In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 664, no 1, p. 397-410Article in journal (Refereed)

Using the neutrino telescope AMANDA-II, we have conducted two analyses searching for neutrino-induced cascades fromgamma-ray bursts. No evidence of astrophysical neutrinos was found, and limits are presented for several models. We also present neutrino effective areas which allow the calculation of limits for any neutrino production model. The first analysis looked for a statistical excess of events within a sliding window of 1 or 100 s ( for short and long burst classes, respectively) during the years 2001-2003. The resulting upper limit on the diffuse flux normalization times E-2 for the Waxman-Bahcall model at 1 PeV is 1.6 x 10(-6) GeVcm(-2) s(-1) sr(-1) (a factor of 120 above the theoretical prediction). For this search 90% of the neutrinos would fall in the energy range 50 TeV to 7 PeV. The second analysis looked for neutrino-induced cascades in coincidence with 73 bursts detected by BATSE in the year 2000. The resulting upper limit on the diffuse flux normalization times E-2, also at 1 PeV is 1.5 x 10(-6) GeV cm(-2) s(-1) sr(-1) (a factor of 110 above the theoretical prediction) for the same energy range. The neutrino-induced cascade channel is complementary to the up-going muon channel. We comment on its advantages for searches of neutrinos from GRBs and its future use with IceCube.

• 37. IceCube Collaboration, -
University of Kalmar, School of Pure and Applied Natural Sciences.
Search for Ultra High-Energy Neutrinos with AMANDA-II2008In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 675, no 2, p. 1014-1024Article in journal (Refereed)

A search for diffuse neutrinos with energies in excess of 105 GeV is conducted with AMANDA-II data recordedbetween 2000 and 2002. Above 107 GeV, the Earth is essentially opaque to neutrinos. This fact, combined with thelimited overburden of the AMANDA-II detector (roughly 1.5 km), concentrates these ultraYhigh-energy neutrinos atthe horizon. The primary background for this analysis is bundles of downgoing, high-energymuons fromthe interactionof cosmic rays in the atmosphere. No statistically significant excess above the expected background is seen in the data,and an upper limit is set on the diffuse all-flavor neutrino flux of E290%CL < 2:7 ; 107 GeV cm2 s1 sr1 valid overthe energy range of 2 ; 105 to 109 GeV. A number of models that predict neutrino fluxes from active galactic nucleiare excluded at the 90% confidence level.

• 38. IceCube Collaboration and InterPlanetary Network, -
University of Kalmar, School of Pure and Applied Natural Sciences.
The Search for Muon Neutrinos from Northern Hemisphere Gamma-Ray Bursts with AMANDA2008In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 674, no 1, p. 357-370Article in journal (Refereed)

We present the results of the analysis of neutrino observations by the Antarctic Muon and Neutrino Detector Array(AMANDA) correlated with photon observations of more than 400 gamma-ray bursts (GRBs) in the northernhemisphere from 1997 to 2003. During this time period,AMANDA’s effective collection area for muon neutrinos waslarger than that of any other existing detector. After the application of various selection criteria to our data, we expect1 neutrino event and<2 background events. Based on our observations of zero events during and immediately priorto the GRBs in the data set, we set the most stringent upper limit on muon neutrino emission correlated with GRBs.Assuming a Waxman-Bahcall spectrum and incorporating all systematic uncertainties, our flux upper limit has anormalization at 1 PeVof E2 6:3 ; 109 GeV cm2 s1 sr1, with 90% of the events expected within the energyrange of 10 TeV to 3 PeV. The impact of this limit on several theoretical models of GRBs is discussed, as well asthe future potential for detection of GRBs by next-generation neutrino telescopes. Finally, we briefly describe severalmodifications to this analysis in order to apply it to other types of transient point sources.

• 39. Kowalski, Marek
University of Kalmar, Department of Technology. University of Kalmar, Department of Technology. University of Kalmar, Department of Technology.
Physics results from the AMANDA neutrino detector2001In: PoS - Proceedings of Science, ISSN 1824-8039, E-ISSN 1824-8039, Vol. HEP2001Article in journal (Refereed)

In the winter season of 2000, the AMANDA (Antarctic Muon And NeutrinoDetector Array) detector was completed to its nal state. We report on major physicsresults obtained from the AMANDA-B10 detector, as well as initial results of the fullAMANDA-II detector.

• 40.
Uppsala and Kalmar Universities.
A Statistical Tool for Finding Non-Particle Events from the AMANDA Neutrino Telescope2004Licentiate thesis, monograph (Other academic)
• 41.
University of Kalmar, School of Pure and Applied Natural Sciences.
Search for Subrelativistic Particles with the AMANDA Neutrino Telescope2009Doctoral thesis, monograph (Other academic)
• 42.
University of Kalmar, School of Pure and Applied Natural Sciences.
Subrelativistic Particle Searches with the AMANDA-II Detector2007In: Proceedings of the 30th International Cosmic Ray Conference: session HE3.4, Vol. 4 (HE part 1), 2007, p. 803-806Conference paper (Other academic)
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