| 1. |
- Achterberg, A., et al.
(författare)
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First Year Performance of the IceCube Neutrino Telescope
- 2006
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Ingår i: Astroparticle physics. - : Elsevier BV. - 0927-6505 .- 1873-2852. ; 26:3, s. 155-173
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 2. |
- Achterberg, A., et al.
(författare)
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Five years of searches for point sources of astrophysical neutrinos with the AMANDA-II neutrino telescope
- 2007
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Ingår i: Physical Review D. Particles, fields, gravitation, and cosmology. - 1550-7998. ; 75:10, s. 102001-
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Tidskriftsartikel (refereegranskat)abstract
- 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 Phi0=((E/(1 TeV)))gamma·((d Phi)/dE) to a point source flux of muon and tau neutrino (detected as muons arising from taus) is Phinu[sub mu] + [overline nu ][sub mu]0+Phinu[sub tau] + [overline nu ][sub tau]0=11.1× 10-11 TeV-1 cm-2 s-1, in the energy range between 1.6 TeV and 2.5 PeV for a flavor ratio Phinu[sub mu] + [overline nu ][sub mu]0/Phinu[sub tau] + [overline nu ][sub tau]0=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 Phinu[sub mu] + [overline nu ][sub mu]0=5.5×10-11 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.
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| 3. |
- Achterberg, A., et al.
(författare)
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Limits on the high-energy gamma and neutrino fluxes from the SGR 1806-20 giant flare of 27 December 2004 with the AMANDA-II detector
- 2006
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 97:22, s. 221101-
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 4. |
- Achterberg, A., et al.
(författare)
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Limits on the Muon Flux from Neutralino Annihilations at the Center of the Earth with AMANDA
- 2006
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Ingår i: Astroparticle physics. - : Elsevier BV. - 0927-6505 .- 1873-2852. ; 26:2, s. 129-139
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Tidskriftsartikel (refereegranskat)abstract
- A search has been performed for nearly vertically upgoing neutrino-induced muons with the Antarctic Muon And Neutrino Detector Array (AMANDA), using data taken over the three year period 1997-99. No excess above the expected atmospheric neutrino background has been found. Upper limits at 90% confidence level have been set on the annihilation rate of neutralinos at the center of the Earth, as well as on the muon flux at AMANDA induced by neutrinos created by the annihilation products.
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| 5. |
- Achterberg, A., et al.
(författare)
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On the selection of AGN neutrino source candidates for a source stacking analysis with neutrino telescopes
- 2006
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Ingår i: Astroparticle physics. - : Elsevier BV. - 0927-6505 .- 1873-2852. ; 26:4-5, s. 282-300
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 6. |
- Achterberg, A., et al.
(författare)
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Search for neutrino-induced cascades from gamma-ray bursts with AMANDA
- 2007
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 664:1, s. 397-410
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Tidskriftsartikel (refereegranskat)abstract
- Using the neutrino telescope AMANDA-II, we have conducted two analyses searching for neutrino-induced cascades from gamma-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 E2 for the Waxman-Bahcall model at 1 PeV is 1.6×10-6 GeV cm-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 E2, also at 1 PeV, is 1.5×10-6 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.
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| 7. |
- Ahrens, J., et al.
(författare)
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Results from AMANDA
- 2001
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Ingår i: Proceedings, 9th International Workshop, Venice, Italy, March 6-9, 2001. Vol. 1, 2. ; , s. 569-580
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Konferensbidrag (refereegranskat)
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| 8. |
- Amanda Collaboration, -, et al.
(författare)
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Optical Properties of Deep Glacial Ice at the South Pole
- 2006
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Ingår i: Journal of Geophysical Research. - 0148-0227 .- 2156-2202 .- 2169-897X. ; 111:D13, s. D13203-
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 9. |
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| 10. |
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