KM3NeT: a deep-sea neutrino telescope in the Mediterranean Sea

1. KM3NeT: a deep-sea neutrino telescope in the Mediterranean Sea Paolo Piattelli - INFN/LNS Catania (Italy) on behalf of the KM3NeT Consortium

2. What is KM3NeT ? • An acronym for km3Neutrino Telescope • A future deep-sea Research Infrastructure hosting a km3 scale neutrino telescope and facilities for associate marine and earth sciences • A Consortium between the groups/Institutions that have developed the pilot neutrino telescope projects in the Mediterranean Sea (Antares, Nemo, Nestor) • Two projects funded by the EU • Design Study (2006-2009): aims at developing a cost-effective design for the construction of a 1 km3 neutrino telescope • Preparatory Phase (2008-2010): preparing for the construction by defining the legal, financial ad governance issues as well as the pre-production of the telescope components

3. Timeline towards construction

4. KM3NeT Conceptual Design Report Describes the scientific  objectives, and the concepts  behind the design, construction, and operation of the KM3NeT Research Infrastructure Will soon be available on the KM3NeT consortium web site http://www.km3net.org

5. Science case • Astroparticle physics with neutrinos • “Point sources”: Galactic and extragalactic sources of high-energy neutrinos • The diffuse neutrino flux • Neutrinos from Dark Matter annihilation • Search for exotics • Magnetic monopoles • Nuclearites, strangelets, … • Neutrino cross sections at high(est) energies • Earth and marine sciences • long-term, continuous measurements in deep-sea • marine biology, oceanography, geology/geophysics, …

6. Why in the Mediterranean Sea? Observed sky region in galactic coordinates assuming efficiency for downwardhemisphere. > 75% Visibility > 25% Visibility

7. Design goals • Sensitivity to exceed IceCube by “substantial factor” • Core process: nm+N  m+X at neutrino energies beyond 100 GeV • Lifetime > 10 years without major maintenance, construction and deployment < 4 years • Some technical specifications: • time resolution 2 ns • position of OMs to better than 40 cm accuracy • two-hit separation < 25 ns • false coincidences dominated by marine background • coincidence acceptance > 50% • PM dark rate < 20% of 40K rate

8. Reference detector • Sensitivity studies with a common detector layout • Geometry: • 15 x 15 vertical detection units on rectangular grid,horizontal distances 95 m • each carries 37 OMs, vertical distances 15.5 m • each OM with21 3’’ PMTs Effective area of reference detector NOT the final KM3NeT design!

9. Point source sensitivity • Based on muon detection • Factor ~3 more sensitive than IceCube • larger photo-cathode area • better direction resolution • Study still needs refinements

10. Diffuse fluxes • Assuming E-2neutrino energy spectrum • Only muonsstudied • Energy reconstruction not yet included

11. Configuration studies • Various geometries and OM configurations have been studied • None is optimal for all energies and directions • Local coincidence requirement poses important constraints

12. KM3NeT CDR contents 7.1. Optical modules 7.2. Information technology 7.3. Mechanics 7.4. Deep-sea and shore infrastructures 7.5. Deployment 7.6. Calibration Introduction Science case The KM3NeT concept Neutrino telescope design goals Pilot projects Site investigations Technical implementation Development plan Project implementation

13. Optical Modules Segmentation of photo cathode of 10” PMT Standard or directional …

14. Optical Modules … or many small PMTs … • Basic idea: Use up to 30 small (3’’ or 3.5’’) PMTs in standard sphere • Advantages: • increased photocathode area • improved 1-vs-2 photo electron separation  better sensitivity to coincidences • directionality • Prototype arrangements under study

15. Optical Modules Quasar 370 (Baikal) … or hybrid solutions … • Idea: Use high voltage (~20kV) and send photo electrons on scintillator;detect scintillator light with small standard PMT. • Advantages: • Very good photo-electron counting • large angular sensitivity possible • Prototype development in CERN/Photonis/CPPM collaboration

16. Mechanical structures Four options considered Tower like String like • Extended tower structure: NESTOR like, arm length up to 60 m • Flexible tower structure: NEMO like, tower deployed in compactified “package” and unfurls thereafter • String structure: Compactified at deployment, unfolding on sea bed • Cable based concept: one (large) OM per storey, separate mechanical and electro-optical function of cable, compactified deployment

17. Deep-sea infrastructure • Major components: • main cable & power transmission • network of secondary cableswith junction boxes • connectors • Design considerations: • cable selection likely to be driven by commercial availability • junction boxes: may be custom-designed • connectors: Expensive, reduce number and/or complexity NEMO junction box design Technology with double vessel system

18. Deployment • Deployment operations require ships or dedicatedplatforms Ships: Buy, charter or use ships of opportunity Platform: Delta-Berenike,under construction in Greece, ready summer 08

19. Associated sciences • The KM3NeT infrastructure will serve as a platform for deep-sea and earth sciences • Strong synergy with the deep-sea science community • Associated sciencedevices will be installed at variousdistances aroundneutrino telescope • KM3NeT site in • ESONET (European Sea-floor Observatory NETwork) • EMSO (European Multi-disciplinary Sea-floor Observatory research infrastructure)

20. Candidate sites • Locations of thethree pilot projects: • ANTARES: Toulon • NEMO: Capo Passero • NESTOR: Pylos • All appear to besuitable • Long-term sitecharacterisationmeasurementsperformed and ongoing • Site decision requiresscientific, technologicaland political input.

21. Summary and conclusions