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Status and Recent Results of the Acoustic Neutrino Detection Test System AMADEUS

Status and Recent Results of the Acoustic Neutrino Detection Test System AMADEUS. Robert Lahmann for the ANTARES Collaboration ARENA 2010, Nantes, 02-July-2010. Outline. Overview of ANTARES and AMADEUS Mediterranean Sea: Acoustic Properties a nd Background Ambient Noise

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Status and Recent Results of the Acoustic Neutrino Detection Test System AMADEUS

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  1. Status and Recent Results of the Acoustic Neutrino Detection Test System AMADEUS Robert Lahmann for the ANTARES Collaboration ARENA 2010, Nantes, 02-July-2010

  2. Outline Overview of ANTARES and AMADEUS Mediterranean Sea:Acoustic Properties and Background Ambient Noise Source Direction Reconstruction Work in Progress Conclusions

  3. Overview of ANTARES and AMADEUS

  4. Goals of AMADEUS Goals to this end: Long-term background investigations Investigation of background correlations (transient/ambient) Development and tests of data filter and reconstruction algorithms Investigation of different types of acoustic sensors and sensing methods Studies of hybrid (acoustic and optical) detection methods Main objective: feasibility study for a potential future large-scale acoustic neutrino detector

  5. ANTARES ~2m Cable ANTARES2500m depth • 12 lines with up to 25 storeys each; total of 885 PMTs • + Instrumentation Line (IL07) • Positioning system: Acoustic emitter (“pinger”) at anchor of each line • Completed 30-May-2008

  6. Principles of Optical and Acoustic Neutrino Detection  Acoustic sensor (hydrophone) array PMTarray optical Cherenkov cone cascade acoustic pressure waves   Cherenkov detector PMT distances in 3D Array: Given by attenuation length(~60m for blue light) Media: water, ice Acoustic detector Sensor distances in 3D Array: ~200m, given by signal geometry (“pancake”) Media: water, ice, homogeneous solids (e.g. salt domes) drawing courtesy L. Thompson (adapted)

  7. ~10cm Setup of Acoustic Storey with Hydrophones Hydrophone:Piezo sensorwith pre-amplifierand band pass filter in PU coating Typical sensitivity: -145 dB re 1V/Pa Titanium cylinderwith electronics 3 custom designed Acoustic ADC boards 16bit @ 250kHz

  8. AMADEUS Setup • 34/36 sensors operational • Continuous data taking with ~90% uptime • Full detector capabilities (time synchronisation, DAQ,…) Operationstarted 5-Dec-2007 Operationstarted 30-May-2008

  9. Acoustic Modules Piezo sensors + preamplifiers Design allows for integration of acoustic sensors into same housing of photo sensors → See talk by A. Enzenhöfer

  10. The Onshore Filter System Task: Reduce incoming data rate of ~1.5 TByte/day to ~10 GByte/day System very flexible Local clusters (storeys) advantageous for fast (on-line) processing

  11. Mediterranean Sea: Acoustic Properties and Background

  12. hadronic cascade ≈10m ≈1km Reminder: Acoustic Signals from Neutrinos Temperature Instantaneous heating, followed by slow cooling Ecasc= 1 EeV @ 1km Adapted from arxiv/0704.1025v1 (Acorne Coll.)

  13. Properties of the Mediterranean Sea (ANTARES site) Speed of sound depends on temperature, salinity, pressure (depth);temperature gradient only relevant up to ~100m below surface

  14. Refraction of Signals Reaching AMADEUS “Open water model”: Using conditions of ANTARES site for complete volumeof the simulation Furthest signals from surface to reach AMADEUS: ~30 km distance, J ~ -5.5° arrival angle

  15. Random noise Bipolar (BIP) events A Bipolar Pressure Signals (BIPs) Have to measure rate of BIP events: Acoustic Background in the Sea Adapted fr. astro-ph/0104033 (Lehtinen et al.) • One hydrophone in principle sufficient • Hydrophone synchronisation not crucial • Hydrophone array required • Hydrophone synchronisation crucial Determines intrinsic energy threshold Determines fake neutrino rate

  16. Ambient Noise

  17. Ambient Noise: Analysis Method One sensor on IL07 evaluated from 2007-12-05 to 2010-01-22 (~ 2 years) total of 18462 minimum bias samples (~10s each) recorded Removing samples with large components at high frequencies (e.g. “pingers“) and non-gaussian distributions:13909 samples (75.4%) remaining Integrate noise PSD from 1 to 50kHz

  18. Ambient Noise: Daily Variation Strong variations over a day; most likely due to shipping traffic

  19. Ambient Noise: Statistical Distribution 95% of timenoise level is below Median:≈ 17 mPa +2 Assuming a constant sensor sensitivity of -145 dB re 1V/µPa (lab calibration),the mean noise level is 25 mPa -2 +7 -5

  20. Ambient Noise: Conclusion 95% of time background is better than (~50 mPa) for f = 1 to 50 kHz Assume detection threshold for bipolar signals of S/N = 2:Pthd = 100 mPa Ethd≈ 10 EeV More precise measurements to follow(e.g. bandwidth not optimised) • Good conditions for neutrino detection (stable threshold, level as expected) • expect BIP rate to determine threshold

  21. Source Direction Reconstruction

  22. Treatment of Neutrino-like (Triggered) Events Calibrate positions of acoustic sensors Reconstruct source directions of BIP signals Combine direction reconstructions to position reconstructions Define fiducial volume Count BIP point sources in volume for different pressure ranges

  23. Position Reconstruction with Hydrophones IL07 L12 Receive signals from emitters on anchors of the 13 lines Reconstruct position of each hydrophone individually using

  24. Position Reconstruction: Angular Resolution Position Reconstruction works excellently Challenge: systematic errors Estimate of systematic error so far: Sufficient for source position reconstruction

  25. Formula Pic with Threshold Source Direction Reconstruction t4 t5 t1 t0 t3 t2 minimize Error: ~3° in φ, < 1° in J 25 25

  26. AMADEUS - Source Direction Distribution Direction reconstruction for one storey All types of transient signals included, sea mammals, ships etc. Origin points north to horizon 26 26

  27. AMADEUS - Source Direction Distribution 0o -60o 90o -90o 120o

  28. Work in Progress

  29. Further Steps Measure density of sources as a function of energy; Subject of Ph.D. thesis C. Richardt; first insights: Fiducial volume must exclude surface “naive” BIP rate from trigger too simple;Need more sophisticated classification → Poster by Max Neff MC simulations tune event classification ( selection, backgr. discrimination) Determine efficiency for neutrino flux Feasibility Study Simulate fake neutrino rate for arbitrary detector design

  30. First Simple Simulations within Framework Use SeaTray framework of KM3NeT/ANTARES, adapted from IceTray framework of IceCube Collaboration  Modular framework, designed for neutrino detection experiments

  31. Conclusions • AMADEUS performance is excellent • The AMADEUS system has all features of an acoustic neutrino telescope (except size) • Can be used as a multi purpose device (studies of neutrino detection, positioning, marine science) • Ambient background stable, level as expected • Observe very diverse transient background, signal classification crucial • Current focus: Work on MC simulations Funded by:

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