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Light tracking through ice and water: Scattering and absorption in heterogeneous media with Photonics
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
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2007 (English)In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, Vol. 581, no 3, 619-631 p.Article in journal (Refereed) Published
Abstract [en]

In the field of neutrino astronomy, large volumes of optically transparent matter like glacial ice, lake water, or deep ocean water are used as detector media. Elementary particle interactions are studied using in situ detectors recording time distributions and fluxes of the faint photon fields of Cherenkov radiation generated by ultra-relativistic charged particles, typically muons or electrons.

The Photonics software package was developed to determine photon flux and time distributions throughout a volume containing a light source through Monte Carlo simulation. Photons are propagated and time distributions are recorded throughout a cellular grid constituting the simulation volume, and Mie scattering and absorption are realised using wavelength and position dependent parameterisations. The photon tracking results are stored in binary tables for transparent access through ansi-c and c++ interfaces. For higher-level physics applications, like simulation or reconstruction of particle events, it is then possible to quickly acquire the light yield and time distributions for a pre-specified set of light source and detector properties and geometries without real-time photon propagation.

In this paper the Photonics light propagation routines and methodology are presented and applied to the IceCube and Antares neutrino telescopes. The way in which inhomogeneities of the Antarctic glacial ice distort the signatures of elementary particle interactions, and how Photonics can be used to account for these effects, is described.

Place, publisher, year, edition, pages
2007. Vol. 581, no 3, 619-631 p.
Keyword [en]
Numerical simulation, Optical properties, Monte Carlo method, Ray tracing, Optical, Neutrino detection
National Category
Physical Sciences
URN: urn:nbn:se:uu:diva-97326DOI: 10.1016/j.nima.2007.07.143ISI: 000251148000007OAI: oai:DiVA.org:uu-97326DiVA: diva2:172207
Available from: 2008-05-15 Created: 2008-05-15 Last updated: 2011-01-14Bibliographically approved
In thesis
1. On the Search for High-Energy Neutrinos: Analysis of data from AMANDA-II
Open this publication in new window or tab >>On the Search for High-Energy Neutrinos: Analysis of data from AMANDA-II
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

A search for a diffuse flux of cosmic neutrinos with energies in excess of 1014 eV was performed using two years of AMANDA-II data, collected in 2003 and 2004. A 20% evenly distributed sub-sample of experimental data was used to verify the detector description and the analysis cuts. A very good agreement between this 20% sample and the background simulations was observed. The analysis was optimised for discovery, to a relatively low price in limit setting power. The background estimate for the livetime of the examined 80% sample is 0.035 ± 68% events with an additional 41% systematical uncertainty.

The total neutrino flux needed for a 5σ discovery to be made with 50% probability was estimated to 3.4 ∙ 10-7 E-2 GeV s-1 sr-1 cm-2 equally distributed over the three flavours, taking statistical and systematic uncertainties in the background expectation and the signal efficiency into account. No experimental events survived the final discriminator cut. Hence, no ultra-high energy neutrino candidates were found in the examined sample. A 90% upper limit is placed on the total ultra-high energy neutrino flux at 2.8 ∙ 10-7 E-2 GeV s-1 sr-1 cm-2, taking both systematical and statistical uncertainties into account. The energy range in which 90% of the simulated E-2 signal is contained is 2.94 ∙ 1014 eV to 1.54 ∙ 1018 eV (central interval), assuming an equal distribution over the neutrino flavours at the Earth. The final acceptance is distributed as 48% electron neutrinos, 27% muon neutrinos, and 25% tau neutrinos.

A set of models for the production of neutrinos in active galactic nuclei that predict spectra deviating from E-2 was excluded.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2008. 134 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 443
neutrinos, neutrino detection, cosmic rays, ultra-high energy, numerical simulation, optical properties, monte carlo method, ray tracing, neutrino detection, AMANDA, IceCube, WIMP
National Category
Physical Sciences
urn:nbn:se:uu:diva-8906 (URN)978-91-554-7225-2 (ISBN)
Public defence
2008-06-11, Polhemsalen, Ångström Laboratory, Lägerhyddsvägen 1, Uppsala, 10:15
Available from: 2008-05-15 Created: 2008-05-15Bibliographically approved

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