Neutrino Telescopy in the Deep Sea  Introduction  Physics with Neutrino Telescopes  ANTARES and Other Current Projects  Aiming at a km 3 Detector in the Mediterranean Sea: KM3NeT  Conclusions and Outlook Elementary Particle Physics Seminar, University of Oxford Uli Katz Univ. Erlangen

Jan 2009 U. Katz: Astroparticle Physics 2 LHC ~E -2.7 ~E -3 ankle 1 part km -2 yr -1 knee 1 part m -2 yr -1 The Mysterious Cosmic Rays  Particles impinging on Earth from outer space carry energies up to eV (the kinetic energy of a tennis ball at ~200km/h.)  The acceleration mechanisms are unknown.  Cosmic rays carry a significant fraction of the energy of the universe – cosmologically relevant!  Neutrinos play a key role in studying the origin of cosmic rays.

Jan 2009 U. Katz: Astroparticle Physics 3 Neutrino Production Mechanism  Neutrinos are expected to be produced in the interaction of high energy nucleons with matter or radiation: Cosmic rays  Simultaneously, gamma production takes place:  Cosmic ray acceleration yields neutrinos and gammas  … but gammas also from purely leptonic processes Cosmic rays

Jan 2009 U. Katz: Astroparticle Physics 4 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 (10 Mpc) protons E<10 19 eV neutrinos Cosmic accelerator

Jan 2009 U. Katz: Astroparticle Physics 5 Neutrino Interaction Signatures  Neutrinos mainly from π-µ-e decays, roughly e : µ :  = 1 : 2 : 0;  Arrival at Earth after oscillations: e : µ :  ≈ 1 : 1 : 1;  Key signature: muon tracks from µ charged current reactions (few 100m to several km long);  Electromagnetic/hadronic showers: “point sources” of Cherenkov light. electromagn. shower hadronic shower muon track hadronic shower hadronic shower

Jan 2009 U. Katz: Astroparticle Physics 6 The Principle of Neutrino Telescopes Role of the Earth:  Screening against all particles except neutrinos.  Atmosphere = target for production of secondary neutrinos. Cherenkov light:  In water: θ C ≈ 43°  Spectral range used: ~ nm. Angular resolution in water:  Better than ~0.3° for neutrino energy above ~10 TeV, 0.1° at 100 TeV  Dominated by angle(  ) below ~10 TeV (~0.6° at 1 TeV)

Jan 2009 U. Katz: Astroparticle Physics 7 The Neutrino Telescope World Map ANTARES + NEMO + NESTOR join their efforts to prepare a km 3 -scale neutrino telescope in the Mediterranean  KM3NeT Design Study

Jan 2009 U. Katz: Astroparticle Physics 8 Muon Reconstruction 1.2 TeV muon traversing the detector.  The Cherenkov light is registered by the photomultipliers with nanosecond precision.  From time and position of the hits the direction of the muon can be reconstructed to ~0.1°.  Minimum requirement: 5 hits … in reality rather 10 hits.  Position calibration to ~10cm required (acoustic methods).

Jan 2009 U. Katz: Astroparticle Physics 9 Muons: The Background from Above Muons can penetrate several km of water if E µ > 1TeV; Identification of cosmic ‘s from above: needs showers or very high energies.

Jan 2009 U. Katz: Astroparticle Physics 10  Association of neutrinos to specific astrophysical objects.  Energy spectrum, time structure, multi-messenger observations provide insight into physical processes inside source.  Measurements profit from very good angular resolution of water Cherenkov telescopes.  km 3 detectors needed to exploit the potential of neutrino astronomy. Neutrinos from Astrophysical Point Sources Southern Sky Northern Sky KM3NeT, IceCube

Jan 2009 U. Katz: Astroparticle Physics 11 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% Mediterranean site: >75% visibility >25% visibility

Jan 2009 U. Katz: Astroparticle Physics 12 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. Direct  connection

Jan 2009 U. Katz: Astroparticle Physics 13 Example candidate accelerators: Active Galactic Nuclei (AGNs) AGNs are amongst the most energetic phenomena in the universe.

Jan 2009 U. Katz: Astroparticle Physics 14 IceCube/AMANDA data  4282 neutrino events in 1001 days live-time  Sky map of excess significance  Presented by Gary Hill at the Neutrino 2006 conference, Santa Fe Do AMANDA/IceCube see Point Sources? IceCube/AMANDA data Random points 3.7  excess 69 out of 100 random sky maps have an excess higher than 3.7 

Jan 2009 U. Katz: Astroparticle Physics 15 High-energy  sources in the Galactic Disk Update June 2006:  6  sources could be/are associated with SNR, e.g. RX J ;  9 are pulsar wind nebulae, typically displaced from the pulsar;  2 binary systems (1 H.E.S.S. / 1 MAGIC);  6 have no known counterparts. W. Hofmann, ICRC 2005

Jan 2009 U. Katz: Astroparticle Physics 16 Example: ’s 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

Jan 2009 U. Katz: Astroparticle Physics 17 Precise Flux Predictions from  ray 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

Jan 2009 U. Katz: Astroparticle Physics 18 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

Jan 2009 U. Katz: Astroparticle Physics 19 Diffuse Fluxes  Assuming E -2 neutrino energy spectrum  Only muons studied  Energy reconstruction not yet included from KM3NeT CDR

Jan 2009 U. Katz: Astroparticle Physics 20 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

Jan 2009 U. Katz: Astroparticle Physics 21 ANTARES: Detector Design 14.5m 100 m 25 storeys, 348 m Junction Box ~70 m  String-based detector;  Underwater connections by deep-sea submersible;  Downward-looking photomultipliers (PMs), axis at 45 O to vertical;  2500 m deep.

Jan 2009 U. Katz: Astroparticle Physics 22  Buoy: −buoyancy ~6400 N; −keeps string vertical to better than 20m displacement at top.  Electro-optical-mechanical cable: −metal wires for power supply etc.; −optical fibers for data; −mechanical backbone of string.  Storeys: −3 optical modules per storey; −titanium cylinder for electronics; −calibration devices (light, acoustics).  Anchor: −deadweight to keep string at bottom; −release mechanism operated by acoustic signal from surface. ANTARES: Detector Strings

Jan 2009 U. Katz: Astroparticle Physics 23 ANTARES: Components of a Storey LED Beacon for time calibration purposes Titanium cylinder housing electronics for readout, calibration, … Hydrophone (RX) for positioning Optical Module

Jan 2009 U. Katz: Astroparticle Physics 24 ANTARES: Optical Modules 43 cm Hamamatsu 10´´ PM  Photomultipliers: − transfer time spread ~2.7ns (FWHM); − quantum efficiency >20% for 330 nm < λ < 460nm;  Glass spheres: − qualified for 600 bar;

Jan 2009 U. Katz: Astroparticle Physics 25 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 !

Jan 2009 U. Katz: Astroparticle Physics Feb ANTARES: First Detector line installed …

Jan 2009 U. Katz: Astroparticle Physics March 2006 (ROV = Remotely operated submersible) … and connected by ROV Victor!

Jan 2009 U. Katz: Astroparticle Physics 28 M. Circella – Status of ANTARES 28 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

Jan 2009 U. Katz: Astroparticle Physics 29  ~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 29 VLVnT08 Neutrino candidates down going Preliminary up going Reconstructed events from data MC Muons (dashed: true; solid: reconstr.) MC neutrinos (dashed: true; solid: reconstr.)

Jan 2009 U. Katz: Astroparticle Physics 30 2 minutes Burst-fraction: fraction of time when rate > baseline + 20% Baseline ( 40 K+biolum.) Bursts from bioluminescence ANTARES: Data from 2500m Depth (MILOM)  Background light: - bioluminescence (bacteria, macroscopic organisms) - decays of 40 K (~30 kHz for 10’’ photomultiplier)  Correlation with water current - Light bursts by macroscopic organisms – induced by pressure variation in turbulent flow around optical modules ?!

Jan 2009 U. Katz: Astroparticle Physics 31 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

Jan 2009 U. Katz: Astroparticle Physics 32 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

Jan 2009 U. Katz: Astroparticle Physics 33  A dedicated deployment platform  In the final stage of construction  Can be important asset for KM3NeT deployment NESTOR: The Delta-Berenike Platform

Jan 2009 U. Katz: Astroparticle Physics 34 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.

Jan 2009 U. Katz: Astroparticle Physics 35  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).

Jan 2009 U. Katz: Astroparticle Physics 36 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