| 1. |
- Ahrens, J., et al.
(författare)
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Calibration and survey of AMANDA with the SPASE detectors
- 2004
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier. - 0168-9002 .- 1872-9576. ; 522:3, s. 347-359
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Tidskriftsartikel (refereegranskat)abstract
- We report on the analysis of air showers observed in coincidence by the Antarctic Muon and Neutrino detector array (AMANDA-B10) and the South Pole Air Shower Experiment (SPASE-1 and SPASE-2). We discuss the use of coincident events for calibration and survey of the deep AMANDA detector as well as the response of AMANDA to muon bundles. This analysis uses data taken during 1997 when both SPASE-1 and SPASE-2 were in operation to provide a stereo view of AMANDA. © 2003 Elsevier B.V. All rights reserved.
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| 2. |
- Ahrens, J., et al.
(författare)
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Measurement of the cosmic ray composition at the knee with the SPASE-2/AMANDA-B10 detectors
- 2004
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Ingår i: Astroparticle physics. - : Elsevier. - 0927-6505 .- 1873-2852. ; 21:6, s. 565-581
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 3. |
- Ahrens, J., et al.
(författare)
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Observation of high energy atmospheric neutrinos with the Antarctic muon and neutrino detector array
- 2002
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Ingår i: Physical Review D. - : American Physical Society. - 1550-7998 .- 1550-2368. ; 66:1, s. 120051-1200520
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 4. |
- Ahrens, J., et al.
(författare)
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Physics and operation of the AMANDA-II high energy neutrino telescope
- 2002
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Ingår i: Proceedings of the SPIE - The International Society for Optical Engineering 2003. - : Institution of Electrical Engineers (IEE). ; , s. 79-91
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Konferensbidrag (refereegranskat)abstract
- 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.
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| 5. |
- Ahrens, J., et al.
(författare)
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Results from the AMANDA telescope
- 2003
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Ingår i: Nuclear Physics A. - : Elsevier. - 0375-9474 .- 1873-1554. ; 721, s. C545-C548
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 6. |
- Ahrens, J., et al.
(författare)
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Results from the Antarctic muon and nuetrino detector array
- 2003
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Ingår i: Nuclear physics B, Proceedings supplements. - : Elsevier. - 0920-5632 .- 1873-3832. ; 118, s. 371-379
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 7. |
- Ahrens, J., et al.
(författare)
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Search for Extraterrestrial Point Sources of Neutrinos with AMANDA-II
- 2004
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 92:7, s. 711021-711025
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 8. |
- Ahrens, J., et al.
(författare)
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Search for neutrino-induced cascades with the AMANDA detector
- 2003
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Ingår i: Physical Review D. - : American Physical Society (APS). - 1550-7998 .- 1550-2368. ; 67:1, s. 012003-
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Tidskriftsartikel (refereegranskat)abstract
- 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)<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)<6. 5×10-6 GeV cm-2 s-1 sr-1, independent of the assumed neutrino flavor flux ratio. © 2003 The American Physical Society.
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| 9. |
- Ahrens, J., et al.
(författare)
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Search for point sources of high-energy neutrinos with AMANDA
- 2003
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Ingår i: Astrophysical Journal Letters. - : Institute of Physics (IOP). - 2041-8205 .- 0004-637X .- 1538-4357. ; 583:2 I, s. 1040-1057
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 10. |
- Andrés, E., et al.
(författare)
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Observation of high-energy neutrinos using Čerenkov detectors embedded deep in Antarctic ice
- 2001
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 410:6827, s. 441-443
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Tidskriftsartikel (refereegranskat)abstract
- Neutrinos are elementary particles that carry no electric charge and have little mass. As they interact only weakly with other particles, they can penetrate enormous amounts of matter, and therefore have the potential to directly convey astrophysical information from the edge of the Universe and from deep inside the most cataclysmic high-energy regions. The neutrino's great penetrating power, however, also makes this particle difficult to detect. Underground detectors have observed low-energy neutrinos from the Sun and a nearby supernova2, as well as neutrinos generated in the Earth's atmosphere. But the very low fluxes of high-energy neutrinos from cosmic sources can be observed only by much larger, expandable detectors in, for example, deep water3,4 or ice5. Here we report the detection of upwardly propagating atmospheric neutrinos by the ice-based Antarctic muon and neutrino detector array (AMANDA). These results establish a technology with which to build a kilometre-scale neutrino observatory necessary for astrophysical observations1.
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