Neutrino Oscillation Workshop 2008 NOW 2008 Conca Specchiulla

Neutrino Oscillation Workshop 2008 (NOW 2008) Conca Specchiulla / Otranto, Italy, 6 -13 Sept. 2008 Underwater Neutrino Telescopes Uli Katz ECAP / Univ. Erlangen 11. 09. 2008 § Introduction § A few words on physics § Current projects § The future: KM 3 Ne. T U. Katz: Underwater neutrino telescopes

The Neutrino Telescope World Map ANTARES + NEMO + NESTOR join their efforts to prepare a km 3 -sized neutrino telescope in the Mediterranean Sea NEMO KM 3 Ne. T 11. 09. 2008 U. Katz: Underwater neutrino telescopes 2

Astro- and Particle Physics with n Telescopes High-energy limit: • neutrino flux decreases like E–n (n ≈ 2) • large detection volume needed. Low-energy limit: • detector sensitivity • background 11. 09. 2008 U. Katz: Underwater neutrino telescopes 3

Fields of View: South Pole vs. Mediterranean 2 p downward sensitivity assumed Located in Mediterranean visibility of given source can be limited to less than 24 h per day 11. 09. 2008 > 25% > 75% U. Katz: Underwater neutrino telescopes 4

Potential Galactic Neutrino Sources § The accelerators of cosmic rays - § Interaction of cosmic rays with interstellar matter - § Supernova remnants Pulsar wind nebulae Micro-quasars … Possibly strong n 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. ”Te. V gamma only” objects? 11. 09. 2008 U. Katz: Underwater neutrino telescopes 5

Neutrinos from Supernova Remnants Example: SNR RX J 1713. 7 -3946 (shell-type supernova remnant) H. E. S. S. : E =200 Ge. V – 40 Te. V § § Acceleration beyond 100 Te. V. Power-law energy spectrum, index ~2. 1– 2. 2. Spectrum points to hadron acceleration n flux ~ g flux § Typical n energies: few Te. V W. Hofmann, ICRC 2005 § 11. 09. 2008 U. Katz: Underwater neutrino telescopes 6

n Flux Predictions from Measurements A. Kappes et al. , B. astro-ph 0607286 Vela X (PWN) Note: hadronic nature of Vela X not clear! measured -ray flux (H. E. S. S. ) mean atm. flux (Volkova, 1980, Sov. J. Nucl. Phys. , 31(6), 784) expected neutrino flux – in reach for KM 3 Ne. T § 1 error bands include systematic errors (20% norm. , 10% index & cut-off) 11. 09. 2008 U. Katz: Underwater neutrino telescopes 7

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 Te. V the neutrino telescope field of view is restricted downwards (n absorption), but sensitivity starts to be significant upwards. Gamma ray bursts - Unique signature: Coincidence with gamma observation in time and direction Source stacking possible 11. 09. 2008 U. Katz: Underwater neutrino telescopes 8

Point Source Sensitivity § § § 1. from KM 3 Ne. T CDR Based on muon detection Why factor ~3 more sensitive than Ice. Cube? larger photocathode area better direction resolution Study still needs refinements 11. 09. 2008 U. Katz: Underwater neutrino telescopes 9

Diffuse Fluxes § Assuming E-2 neutrino energy spectrum § Only muons studied § Energy reconstruction not yet included 11. 09. 2008 1. from KM 3 Ne. T CDR U. Katz: Underwater neutrino telescopes 10

Dark Matter Sensitivity § Scan m. SUGRA parameter space and calculate neutrino flux for each point § Focus on points compatible with WMAP data § Detectability: from KM 3 Ne. T CDR - Blue: ANTARES - Green: KM 3 Ne. T - Red: None of them 11. 09. 2008 U. Katz: Underwater neutrino telescopes 11

The Baikal Experiment § In Lake Baikal, Siberia § Deployment and maintenance from frozen lake surface § Several development stages, first data 1993 § 1998 -2003: NT 200 (8 strings, 192 OMs, 105 m 3) § Since 2005: NT 200+ (4 additional “far strings”, 12 OMs each) § R&D for future large-volume instrument (sparse instrumentation, threshold 10 -30 Te. V) 11. 09. 2008 U. Katz: Underwater neutrino telescopes 12

Baikal Results § Many physics results § NT 200: 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 - … 11. 09. 2008 U. Katz: Underwater neutrino telescopes 13

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. 5 m 25 storeys, 348 m 100 m Junction Box For more details see Eleonora Presani‘s talk on Sunday ~70 m 11. 09. 2008 U. Katz: Underwater neutrino telescopes 14

ANTARES Construction Milestones 2001 – 2003: § § § Main Electro-optical cable in 2001 Junction Box in 2002 Prototype Sector Line (PSL) & Mini Instrumentation Line (MIL) in 2003 2005 – 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 2007 – now: § § § 11. 09. 2008 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 15

ANTARES: First Detector line installed … 14. Feb. 2006 11. 09. 2008 U. Katz: Underwater neutrino telescopes 16

… and connected by ROV Victor! 2. March 2006 (ROV = Remotely operated submersible) 11. 09. 2008 U. Katz: Underwater neutrino telescopes 17

ANTARES: Calibration and Data Taking § § Position reconstruction with acoustic triangulation, direction and tilt measurements Accuracy ~10 cm Timing resolution: – 0. 5 ns from electronics/calibration – 1. 3 ns transit time spread (PMs) – 2. 0 ns chromatic dispersion/ scattering in water Angular resolution for µ’s: 0. 2°-0. 3° Data taking: – 2 x 107 µ triggers in 2007 (5 lines) – 10 - and 12 -line data being analysed – break in July/August 2008 (cable problem, meanwhile repaired) 11. 09. 2008 U. Katz: Underwater neutrino telescopes Junction Box 18

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 crosscheck of detector calibration and online filter efficiency 11. 09. 2008 M. Circella – Status of ANTARES U. Katz: Underwater neutrino telescopes VLVn. T 08 19 19

ANTARES: Atmospheric neutrinos down going § ~5 106 triggers (Feb. -May 2007, 5 lines) § Reconstruction tuned for upgoing tracks § Rate of downward tracks: ~ 0. 1 Hz up going n i m i l e Pr § Rate of neutrino candidates: ~ 1. 4 events/day y r a Neutrino candidates Reconstructed events from data MC Muons (dashed: true; solid: reconstr. ) MC neutrinos (dashed: true; solid: reconstr. ) 11. 09. 2008 M. Circella – Status of ANTARES U. Katz: Underwater neutrino telescopes VLVn. T 08 20 20

NESTOR: Rigid Structures Forming Towers § § § Tower based detector (titanium structures). Dry connections (recover − connect − redeploy). Up- and downward looking PMs (15’’). 4000 -5200 m deep. Test floor (reduced size) deployed & operated in 2003. Deployment of 4 floors planned in 2009 11. 09. 2008 Vision: Tower(s) with 12 floors → 32 m diameter → 30 m between floors → 144 PMs per tower U. Katz: Underwater neutrino telescopes 21

Muon intensity (cm-2 s-1 sr-1) NESTOR: Measurement of the Muon Flux NESTOR Coll. , G Aggouras et al, Astropart. Phys. 23 (2005) 377 Atmospheric muon flux determination and parameterisation by a = 4. 7 0. 5(stat. ) 0. 2(syst. ) I 0 = 9. 0 0. 7(stat. ) 0. 4(syst. ) x 10 -9 cm-2 s-1 sr-1 (754 events) Results agree nicely with previous measurements and with simulations. Zenith Angle (degrees) 11. 09. 2008 U. Katz: Underwater neutrino telescopes 22

NESTOR: The Delta-Berenike Platform § A dedicated deployment platform § In the final stage of construction § Can be important asset for KM 3 Ne. T deployment 11. 09. 2008 U. Katz: Underwater neutrino telescopes 23

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. § § 11. 09. 2008 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 telescopes 24

NEMO Phase I: First steps Geoseismic station SN-1 (INGV) Shore station § Test site at 2000 m depth operational. § Funding ok. 5 km e. o. cable 21 km e. o. Cable with single steel shield 2. 5 km e. o. Cable with double steel shield J J BU J 5 km e. o. cable January 2005: Deployment of § 2 cable termination frames (validation of deep-sea wet-mateable connections) § acoustic detection system (On. DE). Ø 10 optical fibres standard ITU- T G-652 Ø 6 electrical conductors 4 mm 2 11. 09. 2008 U. Katz: Underwater neutrino telescopes 25

NEMO Phase-1: Current Status Deployed January 2005 Nov. 2006: Deployment of JB and mini-tower TSS Frame NEMO mini-tower (4 floors, 16 OM) 300 m Junction Box (JB) Minitower, unfurled Mini-tower, compacted 15 m 11. 09. 2008 U. Katz: Underwater neutrino telescopes 26

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 11. 09. 2008 U. Katz: Underwater neutrino telescopes 27

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) 100 km main electro-optical cable (50 k. W, 20 fibres) ( laid) cable termination frame with DC/DC converter (Alcatel) ( some problems, installation expected Oct. 2008) Full installation by end 2008 11. 09. 2008 U. Katz: Underwater neutrino telescopes 28

What is KM 3 Ne. T – the Vision § Future cubic-kilometre sized neutrino telescope in the Mediterranean Sea § Exceeds Northern-hemisphere telescopes by factor ~50 in sensitivity § Exceeds Ice. Cube sensitivity by substantial factor § Focus of scientific interest: Neutrino astronomy in the energy range 1 to 100 Te. V § Platform for deep-sea research (marine sciences) 11. 09. 2008 U. Katz: Underwater neutrino telescopes 29

KM 3 Ne. T: From the Idea to a Concept 11/2002 3/2004 9/2005 2/2006 First consultations of ANTARES, NEMO and NESTOR 9/2006 3/2008 4/2008 KM 3 Ne. T on ESFRI Roadmap Begin of KM 3 Ne. T Preparatory Phase Design Study proposal submitted KM 3 Ne. T on ESFRI List of Opportunities Begin of Design Study 11. 09. 2008 U. Katz: Underwater neutrino telescopes The KM 3 Ne. T Conceptual Design Report 30

The KM 3 Ne. T Conceptual Design Report § Presented to public at VLVn. T 0 workshop in Toulon, April 2008 § Summarises (a. o. ) - Physics case Generic requirements Pilot projects Site studies available on www. km 3 net. org Technical implementation Development plan Project implementation 11. 09. 2008 U. Katz: Underwater neutrino telescopes 31

KM 3 Ne. T 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 11. 09. 2008 U. Katz: Underwater neutrino telescopes 32

Technical Implementation § Photo-sensors and optical modules § Data acquisition, information technology and electronics § Mechanical structures § Deep-sea infrastructure § Deployment § Calibration § Associated science infrastructure 11. 09. 2008 U. Katz: Underwater neutrino telescopes 33

Optical Modules: Standard or Directional § § A standard optical module, as used in ANTARES Typically a 10’’ PMT in a 17’’ glass sphere A segmented anode and a mirror system allow for directional resolution First prototypes produced 11. 09. 2008 U. Katz: Underwater neutrino telescopes 34

… 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 photoelectron separation better sensitivity to coincidences directionality Prototype arrangements under study 11. 09. 2008 U. Katz: Underwater neutrino telescopes 35

… or Hybrid Solutions § § Idea: Use high voltage (~20 k. V) 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 Quasar 370 (Baikal) Prototype development in CERN/Photonis/CPPM collaboration 11. 09. 2008 U. Katz: Underwater neutrino telescopes 36

Photocathode News § Hamamatsu § § 11. 09. 2008 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! U. Katz: Underwater neutrino telescopes Photonis 37

Configuration Studies § § § 11. 09. 2008 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 telescopes 38

The KM 3 Ne. T 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 Effective area of reference detector This is NOT the final KM 3 Ne. T design! 11. 09. 2008 U. Katz: Underwater neutrino telescopes 39

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 11. 09. 2008 U. Katz: Underwater neutrino telescopes 40

Timeline Towards Construction Note: “Construction” includes the final prototyping stage 11. 09. 2008 U. Katz: Underwater neutrino telescopes 41

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 KM 3 Ne. T detector in the Mediterranean Sea will complement Ice. Cube in its field of view and exceed its sensitivity by a substantial factor 11. 09. 2008 U. Katz: Underwater neutrino telescopes 42

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 Te. V. 11. 09. 2008 U. Katz: Underwater neutrino telescopes 43

Particle Propagation in the Universe protons E>1019 e. V (100 Mpc) Cosmic accelerator neutrinos gammas (0. 01 - 1 Mpc) protons E<1019 e. V 1 parsec (pc) = 3. 26 light years (ly) Photons: absorbed on dust and radiation; Protons/nuclei: deviated by magnetic fields, reactions with radiation (CMB) 11. 09. 2008 U. Katz: Underwater neutrino telescopes 44

Another Case: SNR RXJ 1713. 7 -3946 § § Good candidate for hadronic acceleration. Expected signal well related to measured g flux, but depends on energy cutoff. Few events/year over similar background (1 km 3). KM 3 Ne. T sensitivity in the right ballpark! 11. 09. 2008 A. Kappes et al. , B. astro-ph 0607286 U. Katz: Underwater neutrino telescopes 45

A Downward µ in ANTARES Trigger hit Other hit + Used in fit 11. 09. 2008 M. Circella – Status of ANTARES U. Katz: Underwater neutrino telescopes VLVn. T 08 46 46

ANTARES Event Display Characteristic pattern in height-time diagram, depends on zenith angle and point of closest approach between detection line and µ trajectory upward 11. 09. 2008 M. Circella – Status of ANTARES downward (background) U. Katz: Underwater neutrino telescopes 47 47

ANTARES: The First Neutrino with 10 Strings P 11. 09. 2008 M. Circella – Status of ANTARES U. Katz: Underwater neutrino telescopes VLVn. T 08 y r a i l re n i m 48 48

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. 11. 09. 2008 NESTOR Coll. , G Aggouras et al, Nucl. Inst. Meth, A 552 (2005) 420 measured rates MC simulation MC, atm. muons Threshold 30 m. V U. Katz: Underwater neutrino telescopes 49

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 11. 09. 2008 U. Katz: Underwater neutrino telescopes 50

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 11. 09. 2008 U. Katz: Underwater neutrino telescopes 51

Site Characterisation: An Example Important parameter: water transparency Capo Passero Pylos (460 nm) 11. 09. 2008 Also: optical background, sea currents, sedimentation, biofouling, radioactivity, … U. Katz: Underwater neutrino telescopes 52

The KM 3 Ne. T Preparatory Phase § § “Preparatory Phase”: A new EU/FP 7 funding instrument restricted to ESFRI projects. KM 3 Ne. T proposal endorsed, funded with 5 M€, coordinated by Emilio Migneco / LNS Catania 3 -year project, 3/2008 – 2/2011; kick-off meeting in Catania, 10 -13 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 11. 09. 2008 U. Katz: Underwater neutrino telescopes 53

Deep-sea infrastructure § Major components: § NEMO junction box design 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 11. 09. 2008 U. Katz: Underwater neutrino telescopes 54

A green power concept for KM 3 Ne. T? § Idea: Use wind and/or solar power at KM 3 Ne. T 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. 11. 09. 2008 U. Katz: Underwater neutrino telescopes 55

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 11. 09. 2008 U. Katz: Underwater neutrino telescopes 56

… and in the Deep Sea § Deep-sea submersibles are likely needed for - § § Commercially available ROVs 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 11. 09. 2008 U. Katz: Underwater neutrino telescopes 57