1. Status and First Results of the Acoustic Detection System AMADEUS in ANTARES Robert Lahmann for the ANTARES Collaboration ARENA 08, Rome, 26-June-2008

2. 2Robert Lahmann – ARENA 08, Rome – June 26, 2008 Outline 1.Overview of AMADEUS 2.Technical implementation of AMADEUS 3.First results 4.Conclusions

3. 3Robert Lahmann – ARENA 08, Rome – June 26, 2008 Overview of AMADEUS

4. 4Robert Lahmann – ARENA 08, Rome – June 26, 2008 Reminder: Acoustic Signals from Neutrinos Instantaneous heating, followed by slow cooling hadronic cascade ≈10m ≈1km E casc = 1 EeV @ 1km Adapted from arxiv/0704.1025v1 (Acorne Coll.) Temperature Expect detection threshold E > 10 18 eV (1 EeV) ~

5. 5Robert Lahmann – ARENA 08, Rome – June 26, 2008 Acoustic Background in the Sea One Hydrophone in principle sufficient Hydrophone synchronisation not crucial Random noise Neutrino-like events Hydrophone array required Hydrophone synchronisation crucial Bipolar Pressure Signals (BIPs) Have to measure correlated BIP rate: A Adapted fr. astro-ph/0104033 (Lehtinen et al.)‏

6. 6Robert Lahmann – ARENA 08, Rome – June 26, 2008  Feasibility study for future large scale acoustic detector  Background investigations (rate of neutrino-like signals, localisation of sources)  Investigation of signal correlations on different length scales  Tests of different hydrophones and sensing methods  Development and tests of filter and reconstruction algorithms  Studies of hybrid detection methods Goals of the AMADEUS Project

7. 7Robert Lahmann – ARENA 08, Rome – June 26, 2008 The Acoustic Detection System AMADEUS 6 Hydrophones on 1m scale: Local coincidences for suppression of uncorrelated background Reconstruct direction of source Concept: Local clusters at large distances 6 clusters with a total of 36 sensors Spacings between clusters from 15m to 340m

8. 8Robert Lahmann – ARENA 08, Rome – June 26, 2008 The AMADEUS System Taking data since 5-Dec-2007 Completely installed since 30-May-2008

9. 9Robert Lahmann – ARENA 08, Rome – June 26, 2008 19 commercial hydrophones: all working 11 self-made hydrophones: 9/11 working 3 Acoustic Modules (6 acoustic sensors): all working 34/36 sensors working in total Typical sensitivity of hydrophones: -145 dB re. 1V/  Pa Overview of Acoustic Sensors

10. 10Robert Lahmann – ARENA 08, Rome – June 26, 2008 Technical Implementation of AMADEUS

11. 11Robert Lahmann – ARENA 08, Rome – June 26, 2008  Full detector capabilities (time synchronisation, DAQ,…)  Combines local clusters of acoustic sensors with large cluster spacing  Designed to make use of standard ANTARES hard- and software as much as possible  All data to shore (but off-shore pre-trigger possible)  Triggered data (on-shore) ~10 GByte/day  Continuous data taking with (currently) ~80% uptime Features of AMADEUS

12. 12Robert Lahmann – ARENA 08, Rome – June 26, 2008 AMADEUS Uptime DB problems ANTARES completed! deployment L11 and L12 takeover of sector control

13. 13Robert Lahmann – ARENA 08, Rome – June 26, 2008 Setup of Acoustic Storey with Hydrophones Titanium cylinder with electronics 3 custom designed Acoustic ADC boards ~10cm Hydrophone: Piezo sensor with pre-amplifier and band pass filter in PU coating

14. 14Robert Lahmann – ARENA 08, Rome – June 26, 2008 Characteristics of the Acoustic ADC boards 3 Acoustic ADC boards (AcouADC boards) used per storey, each processing 2 sensors  16 bit digitisation (-2V to +2V)  Bandwidth up to ~125 kHz  Adjustable digitisation rate, max. 500 kSamples/s (Currently using downsampling 2: 250 kSamples/s transmitted to shore, i.e. 3MByte/s for 6 hydrophones)  System extremely flexible due to use of FPGA off-shore (downsampling, adjustable gain 1 to 562, off-shore firmware updates possible)

15. 15Robert Lahmann – ARENA 08, Rome – June 26, 2008 System Response Function Hydrophone (piezo+preamp) Filter (analog+digital), amplifier System response measured in lab prior to deployment for each individual component

16. 16Robert Lahmann – ARENA 08, Rome – June 26, 2008 voltage pulse sent received time(µs) amplitude (V) corrected sensitivity log frequency (kHz) dBre 1V/µPa frequency domain transfer spectrum (raw)‏ dB (V/V) Hydrophone Sensitivity Measurement - Principles log frequency (kHz) sender characteristics dB re 1µPa/V frequency (kHz)

17. 17Robert Lahmann – ARENA 08, Rome – June 26, 2008 Directional Calibration of Hydrophones  - freq sensitivity  - Freq sensitivity Sensitivity measured with calibrated hydrophone, confirmed with reciprocity method In-situ measurements planned 

18. 18Robert Lahmann – ARENA 08, Rome – June 26, 2008 Calibration of AcouADC board 0 100 200 Frequency (kHz) 20 10 0 -60 -80 -100 Phase (rad)‏ PSD (dB re 1V 2 /Hz)‏ 0 100 200 Frequency (kHz) Calibration of : Amplification, non-linearities, frequency response, … System functions parameterised Excellent system stability, fluctuations at %-level

19. 19Robert Lahmann – ARENA 08, Rome – June 26, 2008 Signal Response of AcouADC Board Very good agreement between real and modelled system response

20. 20Robert Lahmann – ARENA 08, Rome – June 26, 2008 The Acoustic DAQ System

21. 21Robert Lahmann – ARENA 08, Rome – June 26, 2008 The Onshore Filter System Task: Reduce incoming data rate of ~1.6 TByte/day to ~10 GByte/day System extremely flexible, all components scalable Allows for coincidence triggers on several hydrophones Local clusters (storeys) big advantage for fast (on-line) processing Acoustic servers: 4 servers in total, 2 for filtering:2 Dualcore, 3 GHz 2 Quadcore, 3 GHz Details in talk by M. Neff

22. 22Robert Lahmann – ARENA 08, Rome – June 26, 2008 First Results

23. 23Robert Lahmann – ARENA 08, Rome – June 26, 2008 Correlation with Weather Conditions Weather conditions measured at Hyères airport, about 30km north of ANTARES site Correlation coefficient ~ 80% Deep-sea noise dominated by sea surface agitation preliminary Hydrophone noise integrated from 1 to 50 kHz preliminary Windspeed (kt): Mean=9.4 kt  (mPa)

24. 24Robert Lahmann – ARENA 08, Rome – June 26, 2008 Power Spectral Density of Background Noise preliminary Observed background noise in deep sea basically as expected Data from two month: Lab measurement

25. 25Robert Lahmann – ARENA 08, Rome – June 26, 2008 Noise distribution in dependence of wind speed Exemplary 10s-slices preliminary

26. 26Robert Lahmann – ARENA 08, Rome – June 26, 2008 Pinger of ANTARES Positioning System (I)‏ Pinger of ANTARES positioning system are also used for positioning of acoustic storeys (work in progress)

27. 27Robert Lahmann – ARENA 08, Rome – June 26, 2008 Pinger of ANTARES Positioning System (II)‏ Pinger signal: Amplitude reduced with distance Temporal structure (1 st and 2 nd ping originate from different positions)

28. 28Robert Lahmann – ARENA 08, Rome – June 26, 2008 Pinger Signals: Comparison of AMs and Hydrophones AMs Hydros

29. 29Robert Lahmann – ARENA 08, Rome – June 26, 2008 Localisation of Transient Signals Reconstruction of source distance with triangulation from several storeys Most probable direction of source Details in talk by C. Richardt

30. 30Robert Lahmann – ARENA 08, Rome – June 26, 2008 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,…) “Acoustic Modules” are an option for acoustic measurements without additional mechanical structures Funded by:

31. 31Robert Lahmann – ARENA 08, Rome – June 26, 2008 Backup Transparencies

32. Acoustic Storeys on Line 12 Storey 23 (6 sensors produced at Erlangen) Storey 22 (6 commercial sensors) ‏ Storey 21 (3 “Acoustic Modules”, 6 sensors in total) Deployment May 2008

33. 33Robert Lahmann – ARENA 08, Rome – June 26, 2008 Acoustic Storeys on the IL07 Storey 2 (6 commercial sensors) Storey 3 (6 sensors produced at Erlangen) Storey 6 (6 commercial sensors) Deployment July 2007

34. 34Robert Lahmann – ARENA 08, Rome – June 26, 2008 Acoustic Modules Piezo sensors + preamplifiers Design allows for integration of acoustic sensors into pressure housing of photo sensors  No need for additional mechanical structures