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Towards a Design for a Large Scale Underwater Neutrino Telescope, Test Deployments, and the Site Studies
Available online at www.sciencedirect.com
Nuclear Physics B (Proc. Suppl.) 229–232 (2012) 568 www.elsevier.com/locate/npbps
Towards a Design for a Large Scale Underwater Neutrino Telescope, Test Deployments, and the Site Studies Tommaso Chiarusia , for the KM3NeT Consortium a INFN
Sezione Bologna, Viale Berti-Pichat 6/2 40127 Bologna
Abstract The KM3NeT consortium has completed a Technical Design Report (TDR) for a proposed multi-cubic-kilometer sized underwater neutrino telescope that will be deployed in the Mediterranean Sea. Highlights of the contents of the TDR will be presented in three poster presentations. In this second of three presentations we will focus on the proposed design options for such a device, and also discuss some recent test deployments and studies at the possible sites. Keywords: underwater neutrino telescopes, high energy neutrino astrophysics
The design of the KM3NeT neutrino telescope [1] builds on the extensive experience of the three pilot projects ANTARES [2], NEMO [3] and NESTOR [4], as well as on deep-sea know-how from other fields of science and industry. The detector size must exceed 1 km2 . Optimizations based on cost, physics sensitivity[5][6][7] and reliability have led to a design made of modular vertical structures, called detection units (DU), which frame the optical modules (OMs). The layout of the DUs, placed in a hexagonal grid as well as in coaxial circles of DUs with a constant or a variable PMT density, affects the detectable neutrino energy range. The angular resolution is mainly biased by the number and arrangement of PMTs. At present time, two alternative designs for the DUs are considered: (i) a multi-PMT OM option with many small PMTs housed in a glass sphere and arranged on vertical string structures (the slender string); (ii) few large PMTs (tipically 6) arranged in clusters (bar or ring framed) with some lateral extent and distributed along tower or string-like vertical structures. Recently, two independent deployment of test structures in the Ionian Sea demonstrated the reliability of the operation procedures and the mechanical robustness of the DU layout for prototypes of both slender and bar categories [8] [9]. In addition, the ANTARES, NEMO and NESTOR collaborations have 0920-5632/$ – see front matter © 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.nuclphysbps.2012.10.009
been carrying out an intense activity of site characterization since several years to investigate the physical, geophysical and oceanographic properties of few candidate sites (see Fig. 1). The most relevant characteristics of the investigated sites, such as water optical properties as well as the limited optical background from natural radioactivity and bioluminescence, are reported in the KM3NeT TDR document [1] and in its references.
Figure 1: The three KM3NeT candidate sites [1] [2] [3] [4] [5] [6] [7] [8] [9]
KM3NeT Consortium web site, http://www.km3net.org. ANTARES web site, http://antares.in2p3.fr. NEMO web site, http://nemoweb.lns.infn.it. NESTOR web site, http://www.nestor.noa.gr. E. Tzamariudaki, this proceedings. A.Tsirigotis, this proceedings. O. Kalekin, this proceedings. http://www.km3net.org/december2009cruise.php. http://www.km3net.org/february2010cruise.php.
Nuclear Physics B (Proc. Suppl.) 229–232 (2012) 568 www.elsevier.com/locate/npbps
Towards a Design for a Large Scale Underwater Neutrino Telescope, Test Deployments, and the Site Studies Tommaso Chiarusia , for the KM3NeT Consortium a INFN
Sezione Bologna, Viale Berti-Pichat 6/2 40127 Bologna
Abstract The KM3NeT consortium has completed a Technical Design Report (TDR) for a proposed multi-cubic-kilometer sized underwater neutrino telescope that will be deployed in the Mediterranean Sea. Highlights of the contents of the TDR will be presented in three poster presentations. In this second of three presentations we will focus on the proposed design options for such a device, and also discuss some recent test deployments and studies at the possible sites. Keywords: underwater neutrino telescopes, high energy neutrino astrophysics
The design of the KM3NeT neutrino telescope [1] builds on the extensive experience of the three pilot projects ANTARES [2], NEMO [3] and NESTOR [4], as well as on deep-sea know-how from other fields of science and industry. The detector size must exceed 1 km2 . Optimizations based on cost, physics sensitivity[5][6][7] and reliability have led to a design made of modular vertical structures, called detection units (DU), which frame the optical modules (OMs). The layout of the DUs, placed in a hexagonal grid as well as in coaxial circles of DUs with a constant or a variable PMT density, affects the detectable neutrino energy range. The angular resolution is mainly biased by the number and arrangement of PMTs. At present time, two alternative designs for the DUs are considered: (i) a multi-PMT OM option with many small PMTs housed in a glass sphere and arranged on vertical string structures (the slender string); (ii) few large PMTs (tipically 6) arranged in clusters (bar or ring framed) with some lateral extent and distributed along tower or string-like vertical structures. Recently, two independent deployment of test structures in the Ionian Sea demonstrated the reliability of the operation procedures and the mechanical robustness of the DU layout for prototypes of both slender and bar categories [8] [9]. In addition, the ANTARES, NEMO and NESTOR collaborations have 0920-5632/$ – see front matter © 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.nuclphysbps.2012.10.009
been carrying out an intense activity of site characterization since several years to investigate the physical, geophysical and oceanographic properties of few candidate sites (see Fig. 1). The most relevant characteristics of the investigated sites, such as water optical properties as well as the limited optical background from natural radioactivity and bioluminescence, are reported in the KM3NeT TDR document [1] and in its references.
Figure 1: The three KM3NeT candidate sites [1] [2] [3] [4] [5] [6] [7] [8] [9]
KM3NeT Consortium web site, http://www.km3net.org. ANTARES web site, http://antares.in2p3.fr. NEMO web site, http://nemoweb.lns.infn.it. NESTOR web site, http://www.nestor.noa.gr. E. Tzamariudaki, this proceedings. A.Tsirigotis, this proceedings. O. Kalekin, this proceedings. http://www.km3net.org/december2009cruise.php. http://www.km3net.org/february2010cruise.php.