1. Overview of AMADEUS and Positioning for KM3NeT
Outline
Overview of AMADEUS and Positioning for KM3NeT
Technical implementation of AMADEUS
Positioning with AMADEUS
Conclusions 1 1

2. Overview of AMADEUS and Positioning for KM3NeT2

3. 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 3 3

4. The AMADEUS System Taking data since 5-Dec-2007
Completely installed since 30-May-2008
“Pingers“ (acoustic RxTx) on each Anchor 4

5. Overview of Acoustic Sensors
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 5 5

6. Piezo sensors + preamplifiers
Acoustic Modules
Piezo sensors + preamplifiers
Design allows for integration of acoustic sensors into pressure housing of photo sensors
 No need for additional mechanical structures 6 6 6 6 6 6

7. 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?
Most answers can be given by investigating AM performance!
This presentation: A look at positioning with AMADEUS

8. Technical Implementation of AMADEUS8

9. Full detector capabilities (time synchronisation, DAQ,…)
Features of AMADEUS
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 9 9

10. 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 10 10

11. 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) 11 11

12. The Acoustic DAQ System12

13. Postioning with AMADEUS13 13

14. Pinger Signals for Reconstruction of Hydrophones and AMs
Hydros 14 14 14

15. 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)
Trigger on first negative peak,…
Stockwerkbild austauschen gegen das von Anneli
…Zero crossing defines treception

16. Position Reconstruction for Hydrophones
Hydrophone Storey L12Fl22

17. First Look: Resolution of Hydro Reconstruction

18. Resolution of Hydrophone Reconstruction: Interpretation of Observations
Why better resolution in z-direction?
Each pinger reconstructs a slightly different position:
Hydrophones are not pointlike: (less pronounced in z-direction)
Uncertainty in position of ANTARES pingers (similar for all directions?)
Hydrophones move during pinger cycle (10~15s)
Piezo diameter ≈25mm
In general, only a sub-set of the ANTARES pingers is used due to shadowing:
This subset varies for each hydrophone and each pinger cycle
Only a first look (further studies required) but looks extremely promising
Expect error on positioning to be dominated by systematic effects

19. Position Reconstruction for Acoustic Modules
AM Storey L12Fl21
ch0
ch1
AM0
ch1
AM1
ch0
AM2
ch0
ch1

20. First Look: Resolution of AM Reconstruction

21. Resolution of Acoustic Module Reconstruction: Interpretation of Observations
Reconstruction more difficult with AMs :
Signals guided inside glass shere: (Signal interference, trigger point more difficult to define)
Acoustic sensors show stronger differences in individual behaviour
Stronger shadowing effect
Reconstruction with AMADEUS AMs can be improved but will not reach precision of hydrophones
Option for KM3NeT:
Principle Design is applicable and easily adaptable.
Some optimization needed (more sensors, study different piezos…)

22. 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: 22 22 22