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					ANTARES:
Towards
Acoustic Detection of
Highest Energy
Neutrinos




     Kay Graf for the ANTARES Collaboration
     Erlangen Centre for Astroparticle Physics
     VLVnT 09, Athens, Oct. 13th – 15th 2009
Outline

•    Motivation
•    The AMADEUS System
•    Positioning
•    Source Reconstruction




Kay Graf (ECAP) – VLVnT 09, Athens – October 2009   2
Motivation




Kay Graf (ECAP) – VLVnT 09, Athens – October 2009   3
       Ultra-high Energy Neutrino Astrophysics

at energies above 1014-15eV:




                                                                      n viable throughout these regions
• universe becomes opaque to
  photons at Mpc range
• CR protons, nuclei are galactic up
  to ~1018eV, suffer GZK cut-off
  above that
• neutrinos unabsorbed at all
  energies
  → sources exist to at least
             3x1020eV


• UHE neutrinos are the only
  viable messenger beyond the                                  P. Gorham
  local universe

       Kay Graf (ECAP) – VLVnT 09, Athens – October 2009   4
     Highest Energy Neutrinos
                                                                                               water/ice
                                                                                                                complementary
• astrophysics:                                                                               Cherenkov
                                                                                                                  techniques
     origin of UHECR                                                                          telescopes

     GZK neutrinos




                                                         Flux × E2 [eV m-2 s-1 sr-1]
                                                                                       10-4

• cosmology:                                                                                                                          TD
                                                                                       10-6
     top-down scenarios
    topological defects
                                                                                       10-8

• particle physics:
     neutrino cross section                                                    10-10
                                                                                               14     16      18        20     22     24
                                                                                                           log10(E[eV])
                                                                                                    T. Karg, arXiv:astro-ph/0608312

          for GZK n: >100km2 ∙ 2p ∙ year detector needed
     Kay Graf (ECAP) – VLVnT 09, Athens – October 2009                                                              5
     (U)HE n Detection Methods

                                                   • balloon
                                                   • satellite                n
                                                                         neutrino

                                                   • telescope                      cascade
                       m                                               sonic wave

                                                                 n
                                                             cascade
               optical
              Cherenkov                  radio
                                       Cherenkov
n   PMT array                                 antenna array             hydrophone array
Optical Cherenkov                           Radio Cherenkov            Acoustic Detection
     water, ice                                  ice, salt, rock            water, ice, salt
    latt < 100m                                 latt ~ 1km (ice)          latt > 1km (water)

                                         + hybrid detectors
     Kay Graf (ECAP) – VLVnT 09, Athens – October 2009                         6
                                                                                                                              peak
   Acoustic Signal Properties                                                                                               pressure
                                                                                                                           (mPa/EeV)
Ecasc= 1 EeV @ 1km                                                                      shower




                                                       distance along shower axis (m)
                                                                                        maximum




                                                                                          log10 (radial distance (m))
                                                                                          log10 (radial distance (m))
  Acorne Coll. astro-ph/0704.1025                                                            T. Karg, astro-ph/0608312v1

       bipolar signal (~10kHz) with disk-like geometry


   Kay Graf (ECAP) – VLVnT 09, Athens – October 2009                                                        7
Simulations of an Acoustic Detector

                             200 acoustic
                             antennas/km3



                                                                Pthres




                                    T. Karg, arXiv:astro-ph/0608312

• strong dependence: Veff(Pthres)
• Pthres mainly given by ambient noise
• a threshold of 5mPa seems reachable in the deep-sea

Kay Graf (ECAP) – VLVnT 09, Athens – October 2009                        8
The AMADEUS System




Kay Graf (ECAP) – VLVnT 09, Athens – October 2009   9
The AMADEUS Project

                                      Feasibility Study
• detector environment (hybrid)

• detector calibration functionality

• sensor design and positioning

• background studies

• signal processing techniques

                    integration of acoustic setup into
                   the ANTARES neutrino telescope

Kay Graf (ECAP) – VLVnT 09, Athens – October 2009         10
The ANTARES Neutrino Telescope


                                                           F


                                                          ANTARES
                                                            site




                                                    • optical Cherenkov
                                                      Telescope
                                                    • 875 PMT
                                                    • at 2500m water depth
                                                    • Vinst~ 200 x 200 x 400 m3


Kay Graf (ECAP) – VLVnT 09, Athens – October 2009                   11
       The AMADEUS System




                                                           • taking data
                                                             since 5-Dec-2007
                                                           • completely installed
                                                             since 30-May-2008
                                                           • acoustics on L12:
“pingers“ (acoustic RxTx) on each anchor                     data from 6-Sep to
                                                             24-Dec 2008
       Kay Graf (ECAP) – VLVnT 09, Athens – October 2009          12
       AMADEUS Facts

• characteristics
   - 36 sensors at 6 storeys
     (1 – 350m distance, 34 active)
   - 16bit @ 250kSps sampling
   - ~ -125dB re 1V/mPa sensitivity
   - ~85-90% uptime
• data acquisition
   -     all data to shore
   -     raw:       20 MByte/s (1.5 TByte/d)
   -     filtered: 0.3 MByte/s (4 GByte/d), up to now: 4 TByte
   -     excellent stability of all DAQ parts




       Kay Graf (ECAP) – VLVnT 09, Athens – October 2009    13
                              Data Samples: Amplitude Histograms
Samples (per ADC count)




                                                                                  Samples (per ADC count)
                          noise at different sensors                                                        noise and transient
                          • gaussian profile                                                                • additional tails
                          • linear correlation between                                                      • ~60dB S/N (SINAD), no
                            sensors (factor ~ 99%)                                                            significant crosstalk

                              Kay Graf (ECAP) – VLVnT 09, Athens – October 2009                                         14
Positioning




Kay Graf (ECAP) – VLVnT 09, Athens – October 2009   15
  Positioning: Method for Reconstruction

use emissions from the ANTARES acoustic positioning
system (not directly connected with AMADEUS)

→ positioning of individual sensors:
  • use absolute time from > 3 pingers:
    | rreception – remission | = cs ¢ (treception – temission – toffset )
  • treception by threshold crossing of signal envelope
  • temission from positioning system


→ position/orientation by fitting storey geometry




  Kay Graf (ECAP) – VLVnT 09, Athens – October 2009                         16
 Positioning: Example




• 5 days of data
• completely independent derivation of heading
 Kay Graf (ECAP) – VLVnT 09, Athens – October 2009   17
Acoustic Modules (AMs)




                                                    Piezo sensors + preamplifiers



                                         design allows for integration of acoustic sensors
                                         into pressure housing of photo sensors
                                          no need for additional mechanical structures


Kay Graf (ECAP) – VLVnT 09, Athens – October 2009                       18
Pinger Signals for Reconstruction of
Hydrophones and AMs
                                                     AMs

                                                    Hydros




  signal quality of AMs slightly degraded w.r.t. hydrophones
  (coupling, ringing of sphere, ...)

Kay Graf (ECAP) – VLVnT 09, Athens – October 2009              19
   Positioning with AMs
                                                           4
                                                       5


                                                                            1


                                                                            0


                                                       2
                                                           3
                                                                    30 mm
                                                               σ
                                                                       2

• calculate difference of individually reconstructed sensor position
• some issues/systematics need to be investigated


   Kay Graf (ECAP) – VLVnT 09, Athens – October 2009           20
Heading on AM Storey
              Sensors 0 and 2




  • systematic effects due to orientation of sensors
    w.r.t. pingers need to be investigated
  • for two sensors with distance at 250mm (in a sphere)
    better than 10° resolution reachable

 Kay Graf (ECAP) – VLVnT 09, Athens – October 2009   21
  Positioning Option for KM3NeT

AMADEUS-like acoustic sensors have the potential to combine:
• positioning
• investigation of acoustic neutrino detection techniques
• marine science
Acoustic Modules (AMs) allow for an integration of acoustic
sensors into Opto-Acoustical Modules (OAMs).


First Measurements in the Lab:
• no significant degradation of performance of acoustic sensors
  by ANTARES HV base
• noise expected mainly from DC-DC converter


  Kay Graf (ECAP) – VLVnT 09, Athens – October 2009    22
Source Reconstruction




Kay Graf (ECAP) – VLVnT 09, Athens – October 2009   23
                         Source Direction Reconstruction: A Dolphin
                                                                                         most probable
                                                                                         source direction
                 1                                                               90




                                                                                                                  Intensity (au)
Amplitude (au)




                                                                              (°)
                 0                                                                   0




             -1                                                                 -90
                     0              0.5                  1                        -180    0                 180
                                 time (ms)                                               f (°)


                         • beam forming or time difference algorithms used
                         • uncertainty <1°
                           (mainly due to binning in the algorithm)
                         Kay Graf (ECAP) – VLVnT 09, Athens – October 2009                 24
         Angular Distribution of Marine Sound Sources
•   direction reconstruction for one storey
•   all types of transient signals included
•   origin points horizontal to north
•   one month of data




         Kay Graf (ECAP) – VLVnT 09, Athens – October 2009   25
Tracking of a Source




• reconstruction with one storey
• all triggered events within 500s displayed


Kay Graf (ECAP) – VLVnT 09, Athens – October 2009   26
Summary

• at UHE neutrinos are the only viable messenger beyond
  the local universe
        • need a >100km2 ∙ 2p ∙ year detector
•    acoustic detection promising candidate
        • complementary to optical and radio techniques
          (hybrid detection)
•    AMADEUS in ANTARES:
     feasibility study for a future acoustic detector
       • dedicated array in a detector environment –
         hybrid detection possible
       • successfully operated since 12/2007
        • return of experience for future arrays (opto-acoustical?)

Funded by:




Kay Graf (ECAP) – VLVnT 09, Athens – October 2009              27

				
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