1. E. MignecoErice, ISCRA 2-13 June 2004 Future cubic kilometer arrays Erice ISCRA School 2004 Emilio Migneco

2. E. MignecoErice, ISCRA 2-13 June 2004 Topics Future cubic kilometer arrays for HE neutrino astronomy Review of existing detectors and projects Future detectors: impact of site parameters architecture simulations and expected performances experimental challenges Future cubic kilometer arrays for HE neutrino astronomy Review of existing detectors and projects Future detectors: impact of site parameters architecture simulations and expected performances experimental challenges

3. E. MignecoErice, ISCRA 2-13 June 2004 The observation of TeV neutrino fluxes requires km 2 scale detectors neutrino muon Cherenkov light ~5000 PMT Connection to the shore neutrino atmospheric muon depth >3000m

4. E. MignecoErice, ISCRA 2-13 June 2004 Neutrino telescopes brief history 80’s:DUMAND R&D 90’s:BAIKAL, AMANDA, NESTOR 2k’s:ANTARES, NEMO R&D 2010:ICECUBE Mediterranean KM3 ? AMANDA ICECUBE Mediterranean km 3 BAIKAL DUMAND Pylos La Seyne Capo Passero

5. E. MignecoErice, ISCRA 2-13 June 2004 The present of HE neutrino detectors Two experiments have recorded HE neutrino events and are currently taking data: BAIKAL in Sibiria AMANDA in South Pole Two experiments have recorded HE neutrino events and are currently taking data: BAIKAL in Sibiria AMANDA in South Pole

6. E. MignecoErice, ISCRA 2-13 June 2004 The pioneer experiment: BAIKAL Baikal-NT: 192 OM arranged in 8 strings, 72 m height effective area >2000 m 2 (E  >1 TeV) 3600 m 1366 m successfully running since 10 years atmospheric neutrino flux measured Depth max 1300m Blue light absorption length ~20 m No 40 K but high bioluminescence rate

7. E. MignecoErice, ISCRA 2-13 June 2004 The largest detector up to date: AMANDA Optical Module AMANDA-II 19 strings 677 OMs Depth 1500-2000m Effective Area  10 4 m 2 (E  TeV) Angular resolution  2° See Silvestri’s talks

8. E. MignecoErice, ISCRA 2-13 June 2004 The future of underice neutrino telescope: ICECUBE The technology for underice detectors is well established. The next step is the construction of the km3 detector ICECUBE. The technology for underice detectors is well established. The next step is the construction of the km3 detector ICECUBE.

9. E. MignecoErice, ISCRA 2-13 June 2004 80 strings (60 PMT each) 4800 10” PMT (only downward looking) 125 m inter string distance 16 m spacing along a string Instrumented volume: 1 km 3 (1 Gton) ICECUBE IceCube will be able to identify  tracks from   for E > 10 11 eV cascades from e for E > 10 13 eV  for E > 10 15 eV The enhanced hot water drill 5 MW

10. E. MignecoErice, ISCRA 2-13 June 2004 ICECUBE vs. AMANDA E µ = 10 TeVE µ = 6 PeV Measure energy by counting the number of fired PMT. (This is a very simple but robust method) AMANDA Halzen Expected energy resolution 0.3 in log(E)

11. E. MignecoErice, ISCRA 2-13 June 2004 Expected ICECUBE perfomances cos  A eff / km 2 Effective area vs. zenith angle (downgoing muons rejected)  above 1 TeV resolution ~ 0.6 - 0.8° for most zenith angles Halzen

12. E. MignecoErice, ISCRA 2-13 June 2004 Scientific motivations for two km3 detectors There are strong scientific motivations that suggest to install two neutrino telescopes in opposite hemispheres : Full sky coverage The Universe is not isotropic at z<<1, observation of transient phenomena Galactic Center only observable from Northern Hemisphere There are strong scientific motivations that suggest to install two neutrino telescopes in opposite hemispheres : Full sky coverage The Universe is not isotropic at z<<1, observation of transient phenomena Galactic Center only observable from Northern Hemisphere The most convenient location for the Northern km3 detector is the Mediterranean Sea: vicinity to infrastructures good water quality good weather conditions for sea operations The most convenient location for the Northern km3 detector is the Mediterranean Sea: vicinity to infrastructures good water quality good weather conditions for sea operations

13. E. MignecoErice, ISCRA 2-13 June 2004 Observation time TeV sources  QSO Galactic centre Galactic coordinates Mediterranean km 3 ICECUBE 1.5  sr common view per day

14. E. MignecoErice, ISCRA 2-13 June 2004 The Mediterranean km 3 detector potentials and payoffs Structures can be recovered: The detector can be maintained The detector geometry can be reconfigured The underwater telescope can be installed at depth  3500 m Muon background reduction Light effective scattering length (>100 m) is much longer than in ice (20 m) Cherenkov photons directionality preserved 40 K decay in water + bioluminescence Optical background and dead time increased Light absorption length in water (70 m) is smaller than in ice (100 m) Less Cherenkov photons detected Sediments and fouling Optical modules obscuration  maintenance

15. E. MignecoErice, ISCRA 2-13 June 2004 The Mediterranean km 3 There are three collaborations active in the Mediterranean Sea: ANTARES, NEMO and NESTOR There are three collaborations active in the Mediterranean Sea: ANTARES, NEMO and NESTOR Capo Passero 3400 m Toulon 2400 m Pylos 3800:4000 m ANTARES NEMONESTOR

16. E. MignecoErice, ISCRA 2-13 June 2004 NESTOR 1 floor equipped with 12 PMTs deployed at 3800 m depth in March 2003 NESTOR aims at installing a “tower” equipped with optical modules of  20.000 m 2 detection area. Resvanis 745 atmospheric muon events reconstructed

17. E. MignecoErice, ISCRA 2-13 June 2004 ANTARES ANTARES is installing a 0.1 km 2 demonstator detector close to Toulon 12 lines 25 storeys / line 3 PMTs / storey 900 PMTs ~70 m 350 m 100 m 14.5 m Submarine links Junction Box 40 km to shore Anchor/line socket to be deployed by 2005-2007 See Sulak’s talk

18. E. MignecoErice, ISCRA 2-13 June 2004 NEMO The NEMO Collaboration is dedicating a special effort in: development of technologies for the km 3 (technical solutions chosen by small scale demostrators are not directly scalable to a km 3 ) search, characterization and monitoring of a deep sea site adequate for the installation of the Mediterranean km 3. The NEMO Collaboration is dedicating a special effort in: development of technologies for the km 3 (technical solutions chosen by small scale demostrators are not directly scalable to a km 3 ) search, characterization and monitoring of a deep sea site adequate for the installation of the Mediterranean km 3.

19. E. MignecoErice, ISCRA 2-13 June 2004 The NEMO test site in Catania A fully equipped facility to test and develop technologies for the Mediterranean km 3 cable: 10 OF; 6 conductors Shore laboratory port of Catania Underwater test site: 21 km E offshore Catania 2000 m depth 2004-2006

20. E. MignecoErice, ISCRA 2-13 June 2004 The NEMO experiment at LNS A 5 km fiber optic link connects the NEMO test site in the port of Catania with the Laboratori Nazionali del Sud INFN Bidirectional optical link

21. E. MignecoErice, ISCRA 2-13 June 2004 The Catania test site and Geostar ESONET The NEMO test site in Catania will also host GEOSTAR a deep sea station for on-line seismic and environmental monitoring by INGV. The NEMO test site will be the Italian site for ESONET (European Seafloor Observatory NETwork).

22. E. MignecoErice, ISCRA 2-13 June 2004 EU FP6 Design Study: KM3NET Astroparticle PhysicsPhysics Analysis System and Product Engineering Information Technology Shore and deep-sea structure Sea surface infrastructure Risk Assessment Quality Assurance Resource ExplorationAssociated Science A Technical Design Report (including site selection) for a Cubic kilometre Detector in the Mediterranean WORK PACKAGES Collaboration of 8 Countries, 34 Institutions Aim to design a deep-sea km 3 -scale observatory for high energy neutrino astronomy and an associated platform for deep-sea science Request for funding for 3 years Thompson The experience and know how of the three collaborations is merging in the KM3-NET activity

23. E. MignecoErice, ISCRA 2-13 June 2004 Towards the Mediterranean km 3 Select an optimal site for the km 3 installation Submarine technology R&D Construction:improve reliability, reduce costs Deployment: define strategies taking profit of the newest technological break-through Connections:improve reliability, reduce costs Electronics technology R&D Readout: reduce power consuption Transmission: increase bandwidth, reduce power consumption Select an optimal site for the km 3 installation Submarine technology R&D Construction:improve reliability, reduce costs Deployment: define strategies taking profit of the newest technological break-through Connections:improve reliability, reduce costs Electronics technology R&D Readout: reduce power consuption Transmission: increase bandwidth, reduce power consumption NEMO activities

24. E. MignecoErice, ISCRA 2-13 June 2004 Towards the Mediterranean km 3 : Site selection Depth Lower atmospheric muon background Water optical transparency Large Cherenkov photons mean free path (absorption) No change of photon direction (scattering) Low biological activity Low optical background (bioluminescence) Low biofouling and sedimentation on Optical Modules Low particulate density (light scattering) Weak and stable deep sea currents Reduced stresses on mechanical structures Reduced stimulation of bioluminescent organisms Distance from the shelf break and from canyons Installation safety (turbidity avalanches) Proximity to the coast and to existing infrastructures Easy access for sea operations Reduction of costs for installation and maintenance Depth Lower atmospheric muon background Water optical transparency Large Cherenkov photons mean free path (absorption) No change of photon direction (scattering) Low biological activity Low optical background (bioluminescence) Low biofouling and sedimentation on Optical Modules Low particulate density (light scattering) Weak and stable deep sea currents Reduced stresses on mechanical structures Reduced stimulation of bioluminescent organisms Distance from the shelf break and from canyons Installation safety (turbidity avalanches) Proximity to the coast and to existing infrastructures Easy access for sea operations Reduction of costs for installation and maintenance

25. E. MignecoErice, ISCRA 2-13 June 2004 Candidate sites for the km 3 ANTARES APpEC Meeting, January 2003 3800:4000 m 2400 m 3400 m NEMO NESTOR

26. E. MignecoErice, ISCRA 2-13 June 2004 Site selection: Expected atmospheric muon fluxes Downgoing muon background is strongly reduced as a function of detector installation depth. Depth  3500 m (equivalent to Gran Sasso, Kamioka,..) is suggested for detector installation NEMO (Capo Passero) NESTOR (Pylos) ANTARES (Toulon) AMANDA (Antarctica) Bugaev BAIKAL

27. E. MignecoErice, ISCRA 2-13 June 2004 Water optical properties absorption a( ) scattering b( ) attenuation c( ) = a( ) + b( ) effective scattering b( ) (1- ) Blue light (~440nm): maximum transmission in water peak of PMT Q.E. (bialkali) Cherenkov emission region L a =1/a glass cutoff Blue light L a ~70 m large area PMT (8”:13”) mu-metal shield Pressure resistant glass housing (17”) Smith & Backer

28. E. MignecoErice, ISCRA 2-13 June 2004 km3 depths interval temperature salinityc(440)a(440) Capo Passero: Seasonal dependence of water optical properties Profiles as a function of depth of oceanographic and optical properties in Capo Passero Seasonal dependence of oceanographical (Temperature and Salinity) and optical (absorption and attenuation) properties has been studied in Capo Passero Variations are only observed in shallow water layers August (3 profiles superimposed) March (4 profiles superimposed) May (2 profiles superimposed) December (2 profiles superimposed) Data taken in Indirect estimation of L b  70 m L a = 66  5 m pure seawater

29. E. MignecoErice, ISCRA 2-13 June 2004 Absorption lengths measured in Capo Passero are close to the optically pure sea water data Differences between Toulon and Capo Passero are observed for the blue light absorption Seawater optical properties in Toulon and Capo Passero NEMO data ANTARES data Optical properties have been measured in joint ANTARES-NEMO campaigns in Toulon and in Capo Passero (July-August 2002)

30. E. MignecoErice, ISCRA 2-13 June 2004 Capo Passero: Optical background Optical background was measured in Capo Passero with different devices. Data are consistent with 30 kHz background on 10” PMT at 0.3 spe (mainly 40 K decay, very few bioluminescence). Optical data are consistent with biological measurements: No luminescent bacteria have been observed in Capo Passero below 2500 m Bioluminescent bacteria concentration 100 ml -1 Schuller

31. E. MignecoErice, ISCRA 2-13 June 2004 Capo Passero: Optical background long term measuremts Measurements were carried out in different seasons showing the same optical background values. Schuller

32. E. MignecoErice, ISCRA 2-13 June 2004 Baserate: median of rate in 15 min for 65 days BurstFraction: fraction of time in 15 min in which rate is >1.2 x baserate Toulon: Optical background measured by prototype line Quiet phases: 60 kHz

33. E. MignecoErice, ISCRA 2-13 June 2004 Capo Passero site characteristics Light absorption lengths (~70 m @ 440 nm) are compatible with optically pure sea water values. Measured values of optical properties are constant through the years (important: variations on L a and L c will directly change the detector effective area) Optical background is low (consistent with 40 K background with only rare occurrences of bioluminescence bursts) The site location is good (close to the coast, flat seabed for hundreds km 2, far from the shelf break and from canyons, far from important rivers) Measured currents are low and regular (2-3 cm/s average; peak value <12 cm/s) The Sedimentation rate is low (about 60 mg m -2 day -1 ) No evidence of recent violent events from core analysis (last 60000 years ago)

34. E. MignecoErice, ISCRA 2-13 June 2004 Towards the Mediterranean km 3 : architecture The design of the Mediterranean km 3 detector is addressed to fit physics requirements: Effective area  1 km 2 Angular resolution close to intrinsic resolution (  0.1° for muons produced by E  10 TeV ) Energy threshold of a few 100 GeV The design of the Mediterranean km 3 detector is addressed to fit physics requirements: Effective area  1 km 2 Angular resolution close to intrinsic resolution (  0.1° for muons produced by E  10 TeV ) Energy threshold of a few 100 GeV Design detector layout and study detector performances as a function of site parameters (depth, water properties,...)

35. E. MignecoErice, ISCRA 2-13 June 2004 km 3 architecture: homogeneous lattice or high local density ? “Tower” detector (5832 PMTs): 81 towers arranged in 9x9 lattice 140 m between towers 20 m beam length 40 m vertical distance between beams Homogeneous detector (5600 PMTs): 400 strings arranged in 20x20 lattice 60 m between strings 60 m vertical distance between PMTs 750 m height 780 m height

36. E. MignecoErice, ISCRA 2-13 June 2004 The NEMO tower Height: compacted15:20 m total750 m instrumented600 m n. beams16 to 20 n. PMT64 to 80 Beams: length20m spacing40 m The NEMO tower is a semi-rigid 3D structure designed to allow easy deployment and recovery. High local PMT density is designed to perform local trigger.

37. E. MignecoErice, ISCRA 2-13 June 2004 km 3 architecture: homogeneous lattice or high local density ? “Tower” detector (5832 PMTs): 81 towers arranged in 9x9 lattice 140 m between towers 20 m beam length 40 m vertical distance between beams Homogeneous detector (5600 PMTs): 400 strings arranged in 20x20 lattice 60 m between strings 60 m vertical distance between PMTs 750 m height 780 m height

38. E. MignecoErice, ISCRA 2-13 June 2004 km 3 architecture: effect of water properties Effective areas and median angles for the two different detector architectures and different optical background rates Simulations performed with the ANTARES simulation package NEMO Tower detector5832 PMTs20 kHz NEMO Tower detector5832 PMTs60 kHz NEMO Tower detector5832 PMTs 120 kHz Homogeneous lattice detector5600 PMTs20 kHz 10  23456 0.2 0.4 0.6 0.8 Log E (GeV) Median (degrees) 10 -2 10 10 0 Effective Area (km 2 ) Optical noise

39. E. MignecoErice, ISCRA 2-13 June 2004 km 3 architecture: angular resolution of the “tower detector” cos  A eff / km 2 Icecube 1  10 TeV 10  100 TeV 100  1000 TeV NEMO simulations: optical background 30 kHz, optical properties of Capo Passero

40. E. MignecoErice, ISCRA 2-13 June 2004 Towards the Mediterranean km 3 : technological challenges electro optical cable: construction and deployment Data transmission system Underwater connections Detector: design and construction deployment and recovery Power transmission system Electronics Power Distribution Acoustic positioning

41. E. MignecoErice, ISCRA 2-13 June 2004 Towards the Mediterranean km 3 : technological challenges Recent break-through in submarine technology Large bandwidth optical fibre telecommunications (DWDM): ”all data to shore” under test in NEMO and ANTARES Low power consumption electronics under test in NEMO Acoustic positioning under test in ANTARES High reliability wet mateable connectors under test in ANTARES and in NEMO Deep sea ROV and AUV technology under test in NEMO and ANTARES Recent break-through in submarine technology Large bandwidth optical fibre telecommunications (DWDM): ”all data to shore” under test in NEMO and ANTARES Low power consumption electronics under test in NEMO Acoustic positioning under test in ANTARES High reliability wet mateable connectors under test in ANTARES and in NEMO Deep sea ROV and AUV technology under test in NEMO and ANTARES

42. E. MignecoErice, ISCRA 2-13 June 2004 km 3 technological challenges: data transmission system Data transmission goals Transmit the full data rate with minimum threshold Only signal digitization should be performed underwater All triggering should be performed on shore Reduce active components underwater Assuming An average rate of 50 kHz (40K background) on each OM Signal sampling (8 bits) at 200 MHz Signal length of 50 ns (true for 40K signals)  10 samples/signal 5 Mbits/s rate from each OM  25 Gbits/s for the whole telescope (5000 OM) Rate affordable with development and integration of available devices for telecommunication systems

43. E. MignecoErice, ISCRA 2-13 June 2004 km 3 technological challenges: data transmission system Possible architecture for the km3 detector Mostly passive componentsVery low power consumption Based on DWDM and Interleaver techniques First Multiplation Stage (Tower base): –16 Channels coming from the 16 tower floors. The channels are multiplexed in one fibre at the base of each tower. Second multiplation stage (secondary JB): –32 channels coming from a couple of tower are multiplexed with an interleaver; –The output is a single fibre for each of the four couples of towers. All the fibres coming from the secondary JB go directly to shore (connection to the main electro-optical cable inside the main JB)

44. E. MignecoErice, ISCRA 2-13 June 2004 km 3 technological challenges: data transmission system

45. E. MignecoErice, ISCRA 2-13 June 2004 km 3 technological challenges: low power electronics  Sampling Freqency: 200MHz  Trigger level remote controlled  Max Power dissipation <200 mW  Input dynamic range 10 bit  Dead time < 0.1%  Time resolution < 1 ns LIRAX2 200 MHz Write 10 MHz Read PLL Stand Alone 200 MHz Slave Clock Generator LIRA’s PLL Shielded T&SPC New full custom VLSI ASIC Presently under final laboratory testing Will be tested in some optical modules in NEMO Power Budget: ANTARES 900 PMTs: 16kW over 40km NEMO 5000 PMTs: 30kW over 100km

46. E. MignecoErice, ISCRA 2-13 June 2004 km 3 technological challenges: underwater connections The tower connections will be performed in air during the tower assembling. Some connections (link of the tower with the Junction Box) must be performed underwater Well tested technology - Solution adopted in Antares and NEMO Expensive: connections must be minimized ROV operated connectionANTARES connection

47. E. MignecoErice, ISCRA 2-13 June 2004 Using this method of construction for the vessels it is possible to decouple the two problems of: resistance to pressure resistance to corrosion Moreover it is possible to use an electrical transformer designed to be employed under pressure. In this way the dimensions of the pressurized vessel and its cost can be reduced. Composite (GRP)Steel Cavity to fill with oil An alternative method to build high pressure vessel km 3 technological challenges: the NEMO junction box

48. E. MignecoErice, ISCRA 2-13 June 2004 km 3 technological challenges: ROV / AUV The ROV deep sea technology (under test in ANTARES) is well established but implies operativity limitations due to ROV-carrier ships costs and availability. Operativity are also dependent on sea state. ROV is bounded to the ship through umbilical cables  Difficult movimentation in a sumbarine jungle of strings/towers ROV AUV

49. E. MignecoErice, ISCRA 2-13 June 2004 Summary I The forthcoming km 3 neutrino telescopes are “discovery” detectors with high potential to solve HE astrophysics basic questions: UHECR sources HE hadronic mechanisms Dark matter... The underice km3 ICECUBE is under way, following the AMANDA experience The Mediterranean km 3 neutrino telescope, when optimized, will be an powerful astronomical observatory thanks to its excellent angular resolution

50. E. MignecoErice, ISCRA 2-13 June 2004 Summary II The feasiblity of km 3 detectors at depth  3500 m is widely accepted The undersea technology for the km 3 is under test and development by three collaborations: ANTARES NEMO NESTOR A proposal for a 3 years design study of the km 3 has been submitted to EU under the KM3-NET The answer is pending but good reasons to be confident

51. E. MignecoErice, ISCRA 2-13 June 2004 The km 3 community is eagerly waiting for the start-up !