Underwater Neutrino Telescopes  Introduction  A few words on physics  Current projects  The future: KM3NeT Neutrino Oscillation Workshop 2008 (NOW 2008) Conca Specchiulla / Otranto, Italy, 6-13 Sept Uli Katz ECAP / Univ. Erlangen

U. Katz: Underwater neutrino telescopes2 The Neutrino Telescope World Map NEMO ANTARES + NEMO + NESTOR join their efforts to prepare a km 3 -sized neutrino telescope in the Mediterranean Sea  KM3NeT

U. Katz: Underwater neutrino telescopes3 Astro- and Particle Physics with Telescopes Low-energy limit: detector sensitivity background High-energy limit: neutrino flux decreases like E –n (n ≈ 2) large detection volume needed.

U. Katz: Underwater neutrino telescopes4 Fields of View: South Pole vs. Mediterranean 2  downward sensitivity assumed Located in Mediterranean  visibility of given source can be limited to less than 24h per day > 75% > 25%

U. Katz: Underwater neutrino telescopes5 Potential Galactic Neutrino Sources  The accelerators of cosmic rays - Supernova remnants - Pulsar wind nebulae - Micro-quasars - …  Interaction of cosmic rays with interstellar matter - Possibly strong signal if CR spectrum harder in Galactic Centre than on Earth (supported by recent MILAGRO results)  Unknown sources – what are the H.E.S.S. ”TeV gamma only” objects?

U. Katz: Underwater neutrino telescopes6 Neutrinos from Supernova Remnants Example: SNR RX J (shell-type supernova remnant) H.E.S.S. : E  =200 GeV – 40 TeV W. Hofmann, ICRC 2005  Acceleration beyond 100 TeV.  Power-law energy spectrum, index ~2.1–2.2.  Spectrum points to hadron acceleration  flux ~  flux  Typical energies: few TeV

U. Katz: Underwater neutrino telescopes7 Flux Predictions from  Measurements  1  error bands include systematic errors (20% norm., 10% index & cut-off) mean atm. flux (Volkova, 1980, Sov.J.Nucl.Phys., 31(6), 784) Vela X (PWN) expected neutrino flux – in reach for KM3NeT measured  -ray flux (H.E.S.S.) A.Kappes et al., astro-ph Note: hadronic nature of Vela X not clear!

U. Katz: Underwater neutrino telescopes8 Potential Extragalactic Neutrino Sources  AGNs - Models are rather diverse and uncertain - The recent Auger results may provide an upper limit / a normalisation point at UHE - Note : At about 100 TeV the neutrino telescope field of view is restricted downwards ( absorption), but sensitivity starts to be significant upwards.  Gamma ray bursts - Unique signature: Coincidence with gamma observation in time and direction - Source stacking possible

U. Katz: Underwater neutrino telescopes9 Point Source Sensitivity  Based on muon detection  Why factor ~3 more sensitive than IceCube? - larger photo- cathode area - better direction resolution  Study still needs refinements from KM3NeT CDR

U. Katz: Underwater neutrino telescopes10 Diffuse Fluxes  Assuming E -2 neutrino energy spectrum  Only muons studied  Energy reconstruction not yet included from KM3NeT CDR

U. Katz: Underwater neutrino telescopes11 Dark Matter Sensitivity  Scan mSUGRA parameter space and calculate neutrino flux for each point  Focus on points compatible with WMAP data  Detectability: -Blue: ANTARES -Green: KM3NeT -Red: None of them from KM3NeT CDR

U. Katz: Underwater neutrino telescopes12 The Baikal Experiment  In Lake Baikal, Siberia  Deployment and maintenance from frozen lake surface  Several development stages, first data 1993  : NT200 (8 strings, 192 OMs, 10 5 m 3 )  Since 2005: NT200+ (4 additional “far strings”, 12 OMs each)  R&D for future large-volume instrument (sparse instrumentation, threshold TeV)

U. Katz: Underwater neutrino telescopes13 E THR GeV Baikal Results  Many physics results  NT200: 372 neutrino candidates in 1038 days (MC: 385 expected from atmospheric neutrinos)  Limits on -point sources (GRBs) -diffuse flux (µ’s, cascades) -WIMP annihilation in Earth -magnetic monopoles -…

U. Katz: Underwater neutrino telescopes14 ANTARES: Detector Design  String-based detector;  Underwater connections by deep-sea submersible;  Downward-looking photomultipliers (PMs), axis at 45 O to vertical;  2500 m deep;  First deep-sea neutrino telescope in operation! 14.5m 100 m 25 storeys, 348 m Junction Box ~70 m For more details see Eleonora Presani‘s talk on Sunday

U. Katz: Underwater neutrino telescopes15 ANTARES Construction Milestones 2001 – 2003:  Main Electro-optical cable in 2001  Junction Box in 2002  Prototype Sector Line (PSL) & Mini Instrumentation Line (MIL) in – April 2007:  Mini Instrumentation Line with OMs (MILOM) operated ~4 months in 2005  Lines 1-5 running (connected between March 2006 and Jan. 2007)  Lines 6+7 deployed March/April – now:  Deployment / connection of remaining lines completed in May 2008  Replacement of MILOM by full instrumentation line (IL)  Physics with full detector !

U. Katz: Underwater neutrino telescopes Feb ANTARES: First Detector line installed …

U. Katz: Underwater neutrino telescopes17 2. March 2006 (ROV = Remotely operated submersible) … and connected by ROV Victor!

U. Katz: Underwater neutrino telescopes18 ANTARES: Calibration and Data Taking Junction Box  Position reconstruction with acoustic triangulation, direction and tilt measurements  Accuracy ~10cm  Timing resolution: – 0.5ns from electronics/calibration – 1.3ns transit time spread (PMs) – 2.0ns chromatic dispersion/ scattering in water  Angular resolution for µ’s: 0.2°-0.3°  Data taking: – 2 x 10 7 µ triggers in 2007 (5 lines) – 10- and 12-line data being analysed – break in July/August 2008 (cable problem, meanwhile repaired)

U. Katz: Underwater neutrino telescopes19 M. Circella – Status of ANTARES 19 VLVnT08 ANTARES: Atmospheric µ Flux  Rate of atmospheric µ’s per storey  depth dependence of µ flux  Good agreement of ANTARES data with simulation  Provides major cross- check of detector calibration and online filter efficiency

U. Katz: Underwater neutrino telescopes20  ~5  10 6 triggers (Feb.-May 2007, 5 lines)  Reconstruction tuned for upgoing tracks  Rate of downward tracks: ~ 0.1 Hz  Rate of neutrino candidates: ~ 1.4 events/day ANTARES: Atmospheric neutrinos M. Circella – Status of ANTARES 20 VLVnT08 Neutrino candidates down going Preliminary up going Reconstructed events from data MC Muons (dashed: true; solid: reconstr.) MC neutrinos (dashed: true; solid: reconstr.)

U. Katz: Underwater neutrino telescopes21 NESTOR: Rigid Structures Forming Towers  Tower based detector (titanium structures).  Dry connections (recover − connect − redeploy).  Up- and downward looking PMs (15’’).  m deep.  Test floor (reduced size) deployed & operated in  Deployment of 4 floors planned in 2009 Vision: Tower(s) with12 floors → 32 m diameter → 30 m between floors → 144 PMs per tower

U. Katz: Underwater neutrino telescopes22 NESTOR: Measurement of the Muon Flux Zenith Angle (degrees) Muon intensity (cm -2 s -1 sr -1 ) Atmospheric muon flux determination and parameterisation by (754 events) Results agree nicely with previous measurements and with simulations.  = 4.7  0.5(stat.)  0.2(syst.) I 0 = 9.0  0.7(stat.)  0.4(syst.) x cm -2 s -1 sr -1 NESTOR Coll., G Aggouras et al, Astropart. Phys. 23 (2005) 377

U. Katz: Underwater neutrino telescopes23  A dedicated deployment platform  In the final stage of construction  Can be important asset for KM3NeT deployment NESTOR: The Delta-Berenike Platform

U. Katz: Underwater neutrino telescopes24 The NEMO Project  Extensive site exploration (Capo Passero near Catania, depth 3500 m);  R&D towards km 3 : architecture, mechanical structures, readout, electronics, cables...;  Simulation. Example: Flexible tower  16 arms per tower, 20 m arm length, arms 40 m apart;  64 PMs per tower;  Underwater connections;  Up- and downward-looking PMs.

U. Katz: Underwater neutrino telescopes25  Test site at 2000 m depth operational.  Funding ok. Shore station 2.5 km e.o. Cable with double steel shield 21 km e.o. Cable with single steel shield JBU J J 5 km e.o. cable Geoseismic station SN-1 (INGV) 5 km e.o. cable  10 optical fibres standard ITU- T G-652  6 electrical conductors  4 mm 2 NEMO Phase I: First steps January 2005: Deployment of  2 cable termination frames (validation of deep-sea wet-mateable connections)  acoustic detection system (O DE).

U. Katz: Underwater neutrino telescopes26 NEMO Phase-1: Current Status 300 m Mini-tower, compacted Mini- tower, unfurled 15 m Nov. 2006: Deployment of JB and mini-tower Junction Box (JB) NEMO mini-tower (4 floors, 16 OM) TSS Frame Deployed January 2005

U. Katz: Underwater neutrino telescopes27 NEMO: Phase-1 Results  Successful deployment and system test, all components functional  Data being analysed (example: muon angular distribution)  Some problems: - Missing buoyancy (tower “laying down”) traced back to buoy production error - Junction Box: Incident at deployment, data transmission problem after some weeks, short after ~5 months  recovery & analysis  some redesign for Phase-2

U. Katz: Underwater neutrino telescopes28 NEMO: Phase-2  Objective: Operation of full NEMO tower (16 floors) and Junction Box at 3400 m depth (Capo Passero site)  Some design modifications (cabling, calibration, power system, bar length 15 m  12 m, …)  Infrastructure: - Shore station in Portopalo di Capo Passero (  under renovation) - Shore power system (  under construction) km main electro-optical cable (50 kW, 20 fibres) (  laid) - cable termination frame with DC/DC converter (Alcatel) (  some problems, installation expected Oct. 2008)  Full installation by end 2008

U. Katz: Underwater neutrino telescopes29 What is KM3NeT – the Vision  Future cubic-kilometre sized neutrino telescope in the Mediterranean Sea  Exceeds Northern-hemisphere telescopes by factor ~50 in sensitivity  Exceeds IceCube sensitivity by substantial factor  Focus of scientific interest: Neutrino astronomy in the energy range 1 to 100 TeV  Platform for deep-sea research (marine sciences)

U. Katz: Underwater neutrino telescopes30 KM3NeT: From the Idea to a Concept 11/2002 3/2008 9/2006 2/2006 9/2005 3/2004 First consultations of ANTARES, NEMO and NESTOR KM3NeT on ESFRI Roadmap KM3NeT on ESFRI List of Opportunities Design Study proposal submitted The KM3NeT Conceptual Design Report Begin of Design Study 4/2008 Begin of KM3NeT Preparatory Phase

U. Katz: Underwater neutrino telescopes31 The KM3NeT Conceptual Design Report  Presented to public at VLVnT0 workshop in Toulon, April 2008  Summarises (a.o.) -Physics case -Generic requirements -Pilot projects -Site studies -Technical implementation -Development plan -Project implementation available on

U. Katz: Underwater neutrino telescopes32 KM3NeT Design Goals  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 40 K rate

U. Katz: Underwater neutrino telescopes33 Technical Implementation  Photo-sensors and optical modules  Data acquisition, information technology and electronics  Mechanical structures  Deep-sea infrastructure  Deployment  Calibration  Associated science infrastructure

U. Katz: Underwater neutrino telescopes34  A segmented anode and a mirror system allow for directional resolution  First prototypes produced  A standard optical module, as used in ANTARES  Typically a 10’’ PMT in a 17’’ glass sphere Optical Modules: Standard or Directional

U. Katz: Underwater neutrino telescopes35 … or Many Small Photomultipliers …  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

U. Katz: Underwater neutrino telescopes36 … 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, high quantum eff. - large angular sensitivity possible  Prototype development in CERN/Photonis/CPPM collaboration Quasar 370 (Baikal)

U. Katz: Underwater neutrino telescopes37 Photocathode News  New photocathode developments by two companies (Hamamatsu, Photonis)  Factor 2 in quantum efficiency  factor 2 in effective photocathode area!  Major gain in neutrino telescope sensitivity! Hamamatsu Photonis

U. Katz: Underwater neutrino telescopes38 Configuration Studies  Various geometries and OM configurations have been studied  None is optimal for all energies and directions  Local coincidence requirement poses important constraints on OM pattern

U. Katz: Underwater neutrino telescopes39 The KM3NeT Reference Detector This is NOT the final KM3NeT design! Effective area of 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 with 21 3’’ PMTs

U. Katz: Underwater neutrino telescopes40 The Associated Science Installation  Associated science devices will be installed at various distances around neutrino telescope  Issues: - interfaces - operation without mutual interference - stability of operation and data sharing  Synergy effects

U. Katz: Underwater neutrino telescopes41 Timeline Towards Construction Note: “Construction” includes the final prototyping stage

U. Katz: Underwater neutrino telescopes42 Summary  Neutrinos would (and will) provide very valuable astrophysical information, complementary to photons and charged cosmic rays  The first generation of deep-sea/lake neutrino telescopes has provided the proof of feasibility of underwater neutrino astronomy and yields exciting data  Exploiting the potential of neutrino astronomy requires cubic-kilometre scale neutrino telescopes providing full sky coverage  The KM3NeT detector in the Mediterranean Sea will complement IceCube in its field of view and exceed its sensitivity by a substantial factor

U. Katz: Underwater neutrino telescopes43 How Do Neutrino Telescopes Work ?  Upward-going neutrinos interact in rock or sea/lake water.  Emerging charged particles (in particular muons) produce Cherenkov light in water.  Detection by array of photomultipliers.  Focus of scientific interest: Neutrino astronomy in the energy range 1 to 100 TeV.

U. Katz: Underwater neutrino telescopes44 Particle Propagation in the Universe Photons: absorbed on dust and radiation; Protons/nuclei: deviated by magnetic fields, reactions with radiation (CMB) 1 parsec (pc) = 3.26 light years (ly) gammas ( Mpc) protons E>10 19 eV (100 Mpc) protons E<10 19 eV neutrinos Cosmic accelerator

U. Katz: Underwater neutrino telescopes45 Another Case: SNR RXJ  Good candidate for hadronic acceleration.  Expected signal well related to measured  flux, but depends on energy cutoff.  Few events/year over similar back- ground (1km 3 ).  KM3NeT sensitivity in the right ballpark! A.Kappes et al., astro-ph

U. Katz: Underwater neutrino telescopes46 Trigger hit Other hit + Used in fit M. Circella – Status of ANTARES 46 VLVnT08 A Downward µ in ANTARES

U. Katz: Underwater neutrino telescopes47 downward (background) Characteristic pattern in height-time diagram, depends on zenith angle and point of closest approach between detection line and µ trajectory ANTARES Event Display upward M. Circella – Status of ANTARES 47

U. Katz: Underwater neutrino telescopes48 ANTARES: The First Neutrino with 10 Strings Preliminary M. Circella – Status of ANTARES 48 VLVnT08

U. Katz: Underwater neutrino telescopes49 NESTOR: Data from the Deep Sea  Trigger rates agree with simulation including background light.  For 5-fold and higher coincidences, the trigger rate is dominated by atmospheric muons. NESTOR Coll., G Aggouras et al, Nucl. Inst. Meth, A552 (2005) 420 Threshold 30mV measured rates MC simulation MC, atm. muons

U. Katz: Underwater neutrino telescopes50 Mechanical Structures 1.Extended tower structure: like NESTOR, arm length up to 60 m 2.Flexible tower structure: like NEMO, tower deployed in compactified “package” and unfurls thereafter 3.String structure: Compactified at deployment, unfolding on sea bed 4.Cable based concept: one (large) OM per storey, separate mechanical and electro-optical function of cable, compactified deployment

U. Katz: Underwater neutrino telescopes51 The Candidate Sites  Locations of the three pilot projects: - ANTARES: Toulon - NEMO: Capo Passero - NESTOR: Pylos  All appear to be suitable  Long-term site characterisation measurements performed and ongoing  Site decision requires scientific, technological and political input

U. Katz: Underwater neutrino telescopes52 Site Characterisation: An Example Important parameter: water transparency Pylos (460 nm) Capo Passero Also: optical background, sea currents, sedimentation, biofouling, radioactivity, …

U. Katz: Underwater neutrino telescopes53 The KM3NeT Preparatory Phase  “Preparatory Phase”: A new EU/FP7 funding instrument restricted to ESFRI projects.  KM3NeT proposal endorsed, funded with 5 M€, coordinated by Emilio Migneco / LNS Catania  3-year project, 3/2008 – 2/2011; kick-off meeting in Catania, March 2008  Major objectives: - Initiate political process towards convergence (includes funding and site selection/decision) - Set up legal structure and governance - Strategic issues: New partners, distributed sites, extendibility - Prepare operation organisation & user communities - Organise pre-procurement with commercial partners - Next-step prototyping

U. Katz: Underwater neutrino telescopes54 Deep-sea infrastructure  Major components: - main cable & power transmission - network of secondary cables with junction boxes - connectors  Design considerations: - cable selection likely to be driven by commercial availability - junction boxes: may be custom-designed, work ongoing in NEMO - connectors: Expensive, reduce number and/or complexity NEMO junction box design

U. Katz: Underwater neutrino telescopes55 A green power concept for KM3NeT?  Idea: Use wind and/or solar power at KM3NeT shore installations to produce the required electrical power.  Requires investment of 4-5 M€.  Can only work if coupled to a larger (public) power network.

U. Katz: Underwater neutrino telescopes56 Deployment: On the surface …  Deployment operations require ships or dedicated platforms.  Ships: Buy, charter or use ships of opportunity.  Platform: Delta-Berenike, under construction in Greece, ready summer 08 Delta-Berenike: triangular platform, central well with crane, water jet propulsion

U. Katz: Underwater neutrino telescopes57 … and in the Deep Sea  Deep-sea submersibles are likely needed for - laying out the deep-sea cable network - making connections to detection units - possibly maintenance and surveillance  Remotely operated vehicles (ROVs) available for a wide range of activities at various depths  Use of autonomous undersea vehicles (AUVs) under study Commercially available ROVs