| 1. |
- Ahrens, J., et al.
(author)
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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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In: Astroparticle physics. - : Elsevier. - 0927-6505 .- 1873-2852. ; 21:6, s. 565-581
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Journal article (peer-reviewed)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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| 2. |
- Niessen, Peter, et al.
(author)
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Recent results from the amanda experiment
- 2003
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In: Proceedings of 38th Rencontres de Moriond on Electroweak Interactions and Unified Theories 15-22 Mar 2003. Les Arcs, France.
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Conference paper (peer-reviewed)abstract
- AMANDA (Antarctic Muon And Neutrino Detector Array) is a neutrino telescope built under the southern polar icecap and its scope is to explore the possibility to detect high energy cosmic neutrinos. This should generate insight into the powerful celestial objects where acceleration mechanisms can bring up to 10 20 eV. We describe the achievements and results from the AMANDA-B10 prototype and the preliminary results from the current AMANDA-II detector which show dramatic increase in sensitivity.
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| 3. |
- Ahrens, J., et al.
(author)
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Muon track reconstruction and data selection techniques in AMANDA
- 2004
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In: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier. - 0168-9002 .- 1872-9576. ; 524:1-3, s. 169-194
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Journal article (peer-reviewed)abstract
- 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.
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| 4. |
- Ahrens, J., et al.
(author)
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Search for Extraterrestrial Point Sources of Neutrinos with AMANDA-II
- 2004
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 92:7, s. 711021-711025
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Journal article (peer-reviewed)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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| 5. |
- Zimmer, Hubert D., et al.
(author)
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Memory for Action : A Distinct Form of Episodic Memory?
- 2001. - 1
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Book (peer-reviewed)abstract
- The book presents in eight chapters our actual knowledge on memory for actions and it gives room to the proponents of the opposing models to develop their view for explaining action memory. In Chapter one, Hubert Zimmer and Ronald Cohen summarize the results of laboratory research on action, i. e. memory for self-performed actions. In Chapter two, Melissa Guynn, Mark McDaniel and Gilles Einstein extend this field on memory for intended actions. They present their view on the prospective memory of actions, and they demonstrate the importance of automatic retrieval in prospective memory. In the following chapter, Johannes Engelkamp presents his motor oriented explanation of action memory. He claims that output processes strongly contribute to memory for performed actions, and that the information which is critical for memory is closely related to the information used in the motor control of overt performance. Reza Kormi-Nouri and Lars-Göran Nilsson (Chapter four) completely disagree with this position. They argue that performing actions may cause specific processes, but that nevertheless action memory is part of a unique episodic memory which stores all types of episodes in a similar way. In the following chapter, Mary Ann Foley and Hilary Ratner put action memory in the broader context of activity memory. Everyday actions are usually performed in social contexts and they are goal-oriented. This aspect is seldom relevant in laboratory research, but the authors show that it is of importance for everyday memory. Then two brief chapters follow in which Nilsson and Kormi-Nouri on the one hand, and Engelkamp on the other hand mutually comment on each others position. In the closing chapter, Hubert Zimmer discusses the presented different attempts in parallel. He is doing this by taking into account the different processes and brain modules which are necessary for a successful control of actions.
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