Hunting for Cosmic Neutrinos in the Deep Sea — The ANTARES Neutrino-Telescope Alexander Kappes Physics Institute Univ. Erlangen-Nuremberg October 14, 2005 LBL, Berkeley  Introduction  The ANTARES Neutrino Telescope  Results from MILOM and Line0  The Future: KM3NeT

October 14, 2005 LBL, Berkeley 2 Alexander Kappes Univ. Erlangen-Nuremberg Cosmic Radiation Discovered in 1912 by Victor Hess during a balloon flight At high energies predominantly consists of: protons and  particles satellites/balloonsshower detectors What are the sources and acceleration mechanisms?

October 14, 2005 LBL, Berkeley 3 Alexander Kappes Univ. Erlangen-Nuremberg Messengers from Deep Space Gammas (R~150 E=10 TeV) produced in electron or hadron acceleration Protons E>10 19 eV (R~50 Mpc) Protons E<10 19 eV Neutrinos Cosmic Accelerator Neutrino production: Reaction of accelerated protons with interstellar medium, 3K microwave background radiation or synchrotron radiation p + p(  ) →  + X   +   e + e +  ) observation of prove for hadron acceleration Neutrino oscillation results in e :  :  ≈ 1 : 1 : 1 e :  :  ≈ 1 : 2 : 0 N ( ) ≈ N ( ) Magnetic fields

October 14, 2005 LBL, Berkeley 4 Alexander Kappes Univ. Erlangen-Nuremberg Detection of Cosmic Neutrinos  A !  X Earth used as shield against all other particles Čerenkov light: Čerenkov angle: 42 o wave lengths used: 350 – 500 nm low cross section requires large detector volumes key reaction:  + N !  + X Detector deployed in deep water / ice to reduce downgoing atmospheric muons p 

October 14, 2005 LBL, Berkeley 5 Alexander Kappes Univ. Erlangen-Nuremberg Physics with Neutrino Telescopes GeVTeVEeVPeV E Low energy limit:  short  tracks )only few photo sensors give signal  in sea water: 40 K + bioluminescence give high background can only be lowered with a denser instrumentation of the water/ice High energy limit:  flux decreases with E -2 … E -3  Large volumes required... and also: - GZK neutrinos - supernova detection - magnetic monopoles -... Dark Matter (WIMPs): direction, energy Cosmic point Sources: direction, (energy) Diffuse neutrino flux: energy, (direction)

October 14, 2005 LBL, Berkeley 6 Alexander Kappes Univ. Erlangen-Nuremberg Current and Future Neutrino Telescopes AMANDA IceCube Medium: ice Data since 1997 under construction NESTOR Medium: sea water; under construction ANTARES Medium: sea water; under construction BAIKAL Medium: fresh water; Data since 1991 R&D project for km 3 detector: NEMO (Mediterranean) Future project (km 3 ): KM3NeT (Mediterranean)

October 14, 2005 LBL, Berkeley 7 Alexander Kappes Univ. Erlangen-Nuremberg Why a telescope in the Mediterranean? Sky coverage complementary to AMANDA/IceCube Allows observation of the Galactic Centre South Pole Mediterranean Sources of VHE  emissions (HESS 2005) notvisible Mkn 501 Mkn 421 Crab SS433 Mkn 501 SS433 Crab VELA GalacticCentre not visible RX J1713 Galactic Centre

October 14, 2005 LBL, Berkeley 8 Alexander Kappes Univ. Erlangen-Nuremberg Neutrinos from H.E.S.S. Sources? Example: SNR RX J (shell-type supernova remnant) W. Hofmann, ICRC 2005 Acceleration beyond 100 TeV. Power law energy spectrum, index ~2.1–2.2. Multi-wavelength spectrum points to hadron acceleration ) neutrino flux ~  flux Detectable in current and/or future neutrino telescopes?!

October 14, 2005 LBL, Berkeley 9 Alexander Kappes Univ. Erlangen-Nuremberg The ANTARES Collaboration 20 Institutes from 6 European countries

October 14, 2005 LBL, Berkeley 10 Alexander Kappes Univ. Erlangen-Nuremberg The ANTARES Detector 460 m 70 m 14.5 m String Optical Module Junction Box Buoy Submersible Cable to Shore station artist´s view (not to scale) Hostile environment:  pressure up to 240 bar  sea water (corrosion)

October 14, 2005 LBL, Berkeley 11 Alexander Kappes Univ. Erlangen-Nuremberg One of 12 ANTARES Strings Buoy  keeps string vertical (horizontal displacement < 20 m) Storey  3 optical modules (45 o downwards)  electronics in titanium cylinder EMC cable  copper wires + glass fibres  mechanical connection between storeys Anchor  connector for cable to junction box  control electronics for string  dead weight  acoustic release mechanism

October 14, 2005 LBL, Berkeley 12 Alexander Kappes Univ. Erlangen-Nuremberg An ANTARES Optical Module Glass spheres:  material: borosilicate glass (free of 40 K)  diameter: 43 cm; 1.5 cm thick  qualified for pressures up to 650 bar B-screening optical module Photomultipliers (PMT):  Ø 10 inch (Hamamatsu)  transfer time spread (TTS)  = 1.3 ns  quantum efficiency: > 1760 V (360 < < 460 nm)

October 14, 2005 LBL, Berkeley 13 Alexander Kappes Univ. Erlangen-Nuremberg Calibration systems Time calibration with pulsed light sources  required precision: 0.5 ns (1ns = 20 cm)  1 LED in each optical module  Optical emitter - LED beacon at 4 different storeys - Laser at anchor Acoustic positioning system  required precision: < 10 cm  receiver (Hydrophone) at 5 storeys  1 transceiver at anchor  autonomous transceiver on sea bottom Tiltmeter and compass at each storey

October 14, 2005 LBL, Berkeley 14 Alexander Kappes Univ. Erlangen-Nuremberg DAQ and Online Trigger Data acquisition:  signals digitized in situ (either wave-form or integrated charge (SPE))  all data above low threshold (~0.3 SPE) sent to shore  no hardware trigger Online trigger:  computer farm at shore station (up to 100 PCs)  data rate from detector ~1GB/s (dominated by background)  trigger criteria: hit amplitudes, local coincidences, causality of hits  trigger output ~1MB/s = 30 TB/year Computer Centre Control room

October 14, 2005 LBL, Berkeley 15 Alexander Kappes Univ. Erlangen-Nuremberg Online Trigger Each PMT sends frame with hits of last 13 ms to shore all 1800 concurrent frames (2 per PMT) are combined to 1 timeslice which is analysed by the online trigger on one PC: Trigger logic: Level 1: coincidences at one storey (  t < 20 ns) or large individual signal (& 2.4 SPE) Level 2: causality condition  t < n / c ·  x Level 3: accept if sufficiently many causally related hits exist cos  C = 1 / n Choice of trigger parameters: discard background events to match allowed trigger output rate (~1 MB/s)

October 14, 2005 LBL, Berkeley 16 Alexander Kappes Univ. Erlangen-Nuremberg Online Trigger Important performance criteria: CPU time per event Scaling of trigger rate with increasing background rate Efficiency for E < 1 TeV ) Dark Matter (WIMP) search Increased sensitivity for certain directions (directional trigger) ) WIMP & point sources Efficiency Bckg rate First studies: Efficiency 100 GeV < E < 1 TeV increases by factor ~2 using directional trigger but a lot of CPU power required ) further investigations necessary

October 14, 2005 LBL, Berkeley 17 Alexander Kappes Univ. Erlangen-Nuremberg Optimising the Online Trigger causality relation:  t < n / c ·  x  x min = minimum of distances of all hit pairs in an accepted event Muons E > 10 GeV Background (100 kHz)  x min < 60 m: Background suppression ≈ 97%, Efficiency loss ≈ 1.5%

October 14, 2005 LBL, Berkeley 18 Alexander Kappes Univ. Erlangen-Nuremberg Signatures of Neutrino Reactions Two basic light sources: Čerenkov photons from muon  track-like source Čerenkov photons from shower  hadronic or electromagnetic  “point-like” source visible in detector in all combinations electromagn. shower hadronic shower muon track hadronic shower hadronic shower

October 14, 2005 LBL, Berkeley 19 Alexander Kappes Univ. Erlangen-Nuremberg Position reconstruction: use timing and position information (x i,y i,z i,t i ) of N hits distance d i between assumed shower position (x,y,z,t) and OM i : subtract d i in pairs ) N-1 linear equations solve system of linear equations algebraically ) # hits ¸ 5 (on at least 3 lines) Shower Reconstruction with ANTARES (PhD thesis B. Hartmann) Results (no cuts):  Position resolution: ~1 m  shift due to elongation of shower (Preliminary) position resolution

October 14, 2005 LBL, Berkeley 20 Alexander Kappes Univ. Erlangen-Nuremberg Shower Reconstruction with ANTARES Direction and energy reconstruction: prefit for direction and energy final parameters ( , , E) ) Log-Likelihood fit N i = # photons in PMT i # photons parameterisation of  c distribution PMT opening angle absorption PMT angular efficiency Results (no cuts):  Event sample: Instrumented volume + 1 absorption length  Angular resolution: 10 TeV)  but large tails in distributions  Energy resolution:  log(E) ¼ 0.1 (E > 100 TeV; 60 kHz bckgr per PMT,) (Preliminary) 60 kHz bckgr per PMT (Preliminary)

October 14, 2005 LBL, Berkeley 21 Alexander Kappes Univ. Erlangen-Nuremberg Shower Reconstruction with ANTARES New idea for minimization strategy: (Diploma thesis R. Auer) common to all events: each minimum lies in broad valley impose grid on parameter plane ( , , E) and calculate likelihood for centre of tiles take l tiles with best likelihood values and divide those into sub-tiles ) compare L of sub-tiles within one tile stop after k iterations ( k ¼ 7) and take tile with best likelihood   Likelihood in  -  plane 60 kHz bckgr per PMT (Preliminary) Results (no cuts):  Event sample: fully contained events; 30 TeV < E < 50 TeV  L function: similar to previous one  angular resolution: ~2.4 o  no tails in distribution

October 14, 2005 LBL, Berkeley 22 Alexander Kappes Univ. Erlangen-Nuremberg Recent Test-Lines: MILOM and Line0 Deployed March 2005, connected April 2005 MILOM: Mini Instrumentation Line with Optical Modules Line0: full line without electronics (test of mechanical structure)

October 14, 2005 LBL, Berkeley 23 Alexander Kappes Univ. Erlangen-Nuremberg MILOM setup Optical components: equipped with final electronics 3+1 optical modules at two storeys timing calibration system:  two LED beacons at two storeys  Laser Beacon attached to anchor acoustic positioning system:  receiver at 1 storey  transceiver (transmitter + receiver) at anchor allows to test all aspects of optical line Instrumentation components: current profiler (ADCP) sound velocimeter water properties (CSTAR, CT)

October 14, 2005 LBL, Berkeley 24 Alexander Kappes Univ. Erlangen-Nuremberg First results from MILOM (selection) Single photon resolution (threshold 4 mV ¼ 0.1 SPE) PMT charge spectrumpulse shape single photon peak Time (ADC channel) time (a.u.) amplitude (a.u.)

October 14, 2005 LBL, Berkeley 25 Alexander Kappes Univ. Erlangen-Nuremberg First results from MILOM (selection) Time calibration with LED beacons: Determination of the relative time offset of 3 optical modules at same storey Usage of large light pulses ) TTS of PMTs small Time difference between optical modules Contribution of electronics to time resolution ca. 0.5 ns  t OM1 – OM0  t OM2 – OM0  =0.75ns  =0.68ns

October 14, 2005 LBL, Berkeley 26 Alexander Kappes Univ. Erlangen-Nuremberg First results from MILOM (selection) Acoustic positioning: Several acoustic transponders installed Currently only results from 1D measurements available Systematic effects under control on the level of 2 mm. Time (day) Distance (m) distance from transponder (anchor) to receiver (first storey) vs. time distribution around daily average Distance (mm)

October 14, 2005 LBL, Berkeley 27 Alexander Kappes Univ. Erlangen-Nuremberg First results from MILOM (Selection) Environmental data: Water temperature + sound velocity Temperature almost constant at 13.2 o C Water temperature determines sound velocity (at given depth) Water temperature Sound velocity Velocity (m/s)

October 14, 2005 LBL, Berkeley 28 Alexander Kappes Univ. Erlangen-Nuremberg First results from MILOM MILOM is a success: Data readout (waveforms + SPE) is working as expected and yields ns timing precision In situ timing calibration reaches required precision for target angular resolution (< 0.3 o für E & 10 TeV) All environmental sensors are working well Continuous data from Slow Control (monitoring of various detector components) Lots of environmental and PMT data are available and are currently analysed

October 14, 2005 LBL, Berkeley 29 Alexander Kappes Univ. Erlangen-Nuremberg Line0 deployed to test mechanical structure equipped with autonomous recording devices  water-leakage sensors  sensors to measure attenuation in electrical and optical fibres recovered in May 2005 Results: no water leaks optical transmission losses at entry/exit of cables into/out of electronics containers  Effect caused by static water pressure; Reason understood and reproduced in pressure tests  Solutions available; detector installation not significantly delayed

October 14, 2005 LBL, Berkeley 30 Alexander Kappes Univ. Erlangen-Nuremberg ANTARES: further schedule Assembly of first complete string (Line 1) started last week Deployment and connection ca. January 2006 Completion of the full detector until 2007 From 2006 on: physics data!

October 14, 2005 LBL, Berkeley 31 Alexander Kappes Univ. Erlangen-Nuremberg The future: km 3 detectors in the Mediterranean HENAP Report to PaNAGIC, July 2002: “The observation of cosmic neutrinos above 100 GeV is of great scientific importance....“ “... a km 3 -scale detector in the Northern hemisphere should be built to complement the IceCube detector being constructed at the South Pole.” “The detector should be of km 3 -scale, the construction of which is considered technically feasible.”

October 14, 2005 LBL, Berkeley 32 Alexander Kappes Univ. Erlangen-Nuremberg Towards a km 3 scale detector scale up new design thin out Existing telescopes “times 50“: to expensive to complicated: production/installation takes forever, maintenance impossible not scalable (band width, power supply,...) R&D required: cost effective solutions: reduction price/volume by factor & 2 Stability Aim: maintenance free detector fast installation time for assembly & deployment shorter than lifetime of detector improved components Large volume with same number of PMTs: PMT distance: given by absorption length in water (~60 m) and PMT characteristics ) efficiency losses for larger distances

October 14, 2005 LBL, Berkeley 33 Alexander Kappes Univ. Erlangen-Nuremberg The future: KM3NeT Start of the initiative Sept. 2002; intensive discussions and coordination meetings since beginning of 2003 VLVnT Workshop, Amsterdam, Oct ! second workshop Nov in Catania ApPEC review, Nov Proposal submission to EU 4. March 2004 EU offer about 9 M€, July 2005 (total budget ~20 M€);  Start of the Design Study beginning of 2006; Goal: Technical Design Report after 36 months  Start of construction shortly afterwards EU FP6: Design-Studie for a “Deep-Sea Facility in the Mediterranean for Neutrino Astronomy and Associated Sciences”

October 14, 2005 LBL, Berkeley 34 Alexander Kappes Univ. Erlangen-Nuremberg The future: KM3NeT Germany: Univ. Erlangen, Univ. Kiel France: CEA/Saclay, CNRS/IN2P3 (CPP Marseille, IreS Strasbourg, APC Paris), UHA Mulhouse, IFREMER Italy: CNR/ISMAR, INFN (Univ. Bari, Bologna, LNS Catania, Genova, Naples, Pisa, Rom-1, LNS Catania, LNF Frascati), INGV, Tecnomare SpA Greece: HCMR, Hellenic Open Univ., NCSR Democritos, NOA/Nestor, Univ. Athens Netherlands: FOM (NIKHEF, Univ. Amsterdam, Univ. Utrecht, KVI Groningen) Spain: IFIC/CSIC Valencia, Univ. Valencia, UP Valencia UK: Univ. Aberdeen, Univ. Leeds, Univ. Liverpool, Univ. Sheffield Cyprus: Univ. Cyprus Particle/Astroparticle institutes (16) – Sea science/technology institutes (6) – Coordinator Partners in the Design Study: (contains ANTARES, NEMO, NESTOR projects)

October 14, 2005 LBL, Berkeley 35 Alexander Kappes Univ. Erlangen-Nuremberg Detector studies at Erlangen (S. Kuch) The future: KM3NeT Example (NIKHEF): Advantages: higher quantum efficiency better timing resolution directional information almost 4  sensitivity less penetrators First studies running since a few months inhomogeneous km 3 detector neutrino energy  effective area homogeneous km 3 detector with same # cylinders factor ~3 better for E < 1 TeV Example:

October 14, 2005 LBL, Berkeley 36 Alexander Kappes Univ. Erlangen-Nuremberg Conclusions ANTARES:  Compelling physics arguments for ANTARES  Shower reconstruction very important; algorithms with good performance available  MILOM: data readout is working as expected; in situ timing calibration sufficient to reach angular resolution 10 TeV  Line0: mechanical structure water tight and pressure resistant; losses in optical fibres at interface ) solutions available  Installation of first complete string about Jan. 2006; Completion of the whole detector until 2007 Well prepared for physics date to come in 2006 KM3NeT: future km 3 -scale -telescope in the Mediterranean  km 3 -scale telescope on the Northern Hemisphere complementary to IceCube at the South Pole  3 year EU funded Design Study (~20 M€): expected start beginning 2006