1. Latest Results with the Acoustic Modules of the AMADEUS Acoustic System in ANTARES
T. Eberl for Robert Lahmann and the Erlangen acoustic group
KM3NeT WP2,3,4,5 joint meeting Paris, 23-Feb-2009 1 1 1

2. The AMADEUS Project
The AMADEUS project extends the ANTARES detector by a dedicated array of acoustic sensors
The main goal is the investigation of techniques for acoustic particle detection
The system can be used as a multiple purpose device (studies of neutrino detection, marine science, positioning,…)
For more details:
Webpage of the AMADEUS project:
Presentation from last WP3 meeting (Paris 18-Oct-2008): 2 2

3. The AMADEUS System Taking data since 5-Dec-2007
Completely installed since 30-May-2008
Acoustics on L12: Data from Sep to 24-Dec-2008
“Pingers“ (acoustic RxTx) on each Anchor 3

4. Features of AMADEUS 30 hydrophones: 28/30 working
3 Acoustic Modules (6 acoustic sensors): all working
Typical sensitivity of hydrophones: -145 dB re. 1V/Pa (including preamplifier)
16-bit 250 kSps (1~100 kHz bandwidth)
Amplification of analogue signal from 1 to 562
All data to shore (but off-shore pre-trigger possible)
Triggered data (on-shore) ~15 GByte/day (Data reduction by factor of ~100)
Continuous data taking with (currently) >80% uptime (not counting failure of sector on L12) 4 4

5. Piezo sensors + preamplifiers
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 5 5 5 5 5 5

6. Positioning Option for KM3NeT
AMADEUS-like acoustic sensors have the potential to combine:
positioning
investigation of acoustic neutrino detection techniques
marine science
The Acoustic Modules (AMs) allow for an integration of acoustic sensors into Optical Modules.
Are piezo elements within a PMT housing an inexpensive option for a multi purpose acoustic system for KM3NeT?
Many answers can be given by investigating AM performance!
This presentation: Only results with AMs

7. Methods for Position Reconstruction goal: positioning at cm-level (4s sampling ≙ 6mm)
Main Method – using database info about emission time of pinger signals
positioning of individual sensors
use absolute time for the 14 pingers: cs  (treception – temission – toffset )
Trigger on first negative peak,…
Stockwerkbild austauschen gegen das von Anneli
…Zero crossing defines treception

8. Position Reconstruction for Acoustic Modules
Same method for AMs, but distortion of signal due to interferences in glass sphere;
Apply trigger threshold on envelope

9. Resolution of Position Reconstruction for AMs
Calculate difference of individually reconstructed sensor position
Systematic effects due to orientation of sensors w.r.t. pingers need to be investigated

10. Measurement of Heading with Acoustic Modules I
Fit known positions of sensors in coordinate system of the storey to the reconstructed positions

11. Measurement of Heading with Acoustic Modules II
Systematic effects due to orientation of sensors w.r.t. pingers need to be investigated

12. Acoustic Modules for KM3NeT?
Principle Design is applicable and easily adaptable.
Some questions need to be addressed with lab measurements:
Precision or reconstruction for acoustic sensors in one module
How many sensors per module are needed?
Effect of HV of PMTs in same module

13. 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, marine science, positioning,…)
“Acoustic Modules” are an option for acoustic measurements without additional mechanical structures for KM3Net
AMADEUS design flexible: adaptable to KM3NeT design and DAQ hardware
As option for KM3NeT: More studies with AMADEUS and in laboratory required
Funded by: 13 13 13

14. Backup slides

15. Goals of the AMADEUS Project
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 15 15

16. Setup of Acoustic Storey with Hydrophones
Hydrophone: Piezo sensor with pre-amplifier and band pass filter in PU
coating
~10cm
Titanium cylinder with electronics
3 custom designed Acoustic ADC boards 16 16

17. Pinger Signals for Reconstruction of Hydrophones and AMs
Hydros 17 17 17

18. 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) 18 18