1. Acoustic Calibration for the KM3NeT Pre-Production Module Alexander Enzenhöfer on behalf of the KM3NeT consortium VLV T 2011 Erlangen, 12.10. – 14.10.2011

2. Why and how to do acoustic calibration 2 Alexander Enzenhöfer, VLVnT 2011, 12.10.2011

3. Why acoustic calibration? Deep sea as highly dynamic environment: Variable sea current, in both speed and direction Need to know PMT-positions with ~20 cm precision Necessity for calibration signals with acceptable attenuation in water (only ~100 m for light, ~1 km for sound) Low cost with possibility to use commercial systems 3 Alexander Enzenhöfer, VLVnT 2011, 12.10.2011

4. Requirements for used devices Withstand high ambient pressure Capability to detect small signal amplitudes Sea water durability Simplicity Reliability High duty cycle 4 Alexander Enzenhöfer, VLVnT 2011, 12.10.2011

5. Acoustic calibration principle Usage of dedicated emitters and receivers Emitters at fixed positions on the sea floor Receivers attached to detection units Based on the piezoelectric effect Different signals (frequency, length or shape) to distinguish between different emitters Triangulation of the detection units using signal arrival times and known emitter positions 5 Alexander Enzenhöfer, VLVnT 2011, 12.10.2011

6. Variety of different devices Commercial devices (cf. talk ID 91 afterwards) Custom-built devices (AMADEUS/ANTARES, NEMO (cf. talk ID 60 before)) Various geometries, frequency ranges, … 6 Alexander Enzenhöfer, VLVnT 2011, 12.10.2011

7. Our concept: Further development of Acoustic Modules in ANTARES 7 Alexander Enzenhöfer, VLVnT 2011, 12.10.2011

8. Acoustic Module in ANTARES Developed at the ECAP 3 Acoustic Modules integrated in AMADEUS Acoustic sensor glued to the inside of pressure resistant housing Acoustic sensor protected against environmental influences No additional feedthrough Show good results for storey positioning 8 Alexander Enzenhöfer, VLVnT 2011, 12.10.2011

9. Measurement of Heading with Acoustic Modules Fit known positions of sensors in coordinate system of the storey to the reconstructed positions 9 Alexander Enzenhöfer, VLVnT 2011, 12.10.2011

10. Positioning option for KM3NeT Potential of acoustic sensors: Positioning Investigation of acoustic neutrino detection techniques Marine science Acoustic Modules (AMs) allow for an integration of acoustic sensors into Optical Modules Feasibility for KM3Net has to be tested PPM 10 Alexander Enzenhöfer, VLVnT 2011, 12.10.2011

11. Concept of a combined Opto-Acoustical Module Optical Module: PMT(s) integrated into pressure resistant housing Acoustic Module: Acoustic sensors integrated into pressure resistant housing Opto-Acoustical Module (OAM): PMT and acoustic sensor integrated into pressure resistant housing 11 Alexander Enzenhöfer, VLVnT 2011, 12.10.2011

12. Possible disadvantage resulting from combination Design dependent angular acceptance Electronic interference Module power supply (supply/generation of different voltages inside the module) PMT HV supply PMT operation and piezo operation Interface water-glas-piezo Complex signal path through the glass sphere Coupling of the piezo to the glass 12 Alexander Enzenhöfer, VLVnT 2011, 12.10.2011

13. First results (old design) Integrated PMT influence RMS noise ≈ 5 x RMS typ. sea-state 13 Alexander Enzenhöfer, VLVnT 2011, 12.10.2011 Recorded noise spectra (sensor totally unshielded)

14. Acoustic sensor – new prototype New design: Compact Better shielding Different amplifier layout 14 Alexander Enzenhöfer, VLVnT 2011, 12.10.2011

15. Cooperation in the context of KM3NeT activities 15 Alexander Enzenhöfer, VLVnT 2011, 12.10.2011

16. Cooperation with LNS-INFN Catania Integration of acoustic sensors inside single PMT optical module 16 Alexander Enzenhöfer, VLVnT 2011, 12.10.2011

17. Results using NEMO Phase II infrastructure Noise spectrum without PMT (ECAP sensor (top), NEMO hydrophone (bottom)) Noise spectrum with powered PMT (ECAP sensor (top), NEMO hydrophone (bottom)) 17 Alexander Enzenhöfer, VLVnT 2011, 12.10.2011

18. Cooperation for KM3NeT PPM Integration of acoustic sensor inside multi PMT optical module (Digital Optical Module) 18 Alexander Enzenhöfer, VLVnT 2011, 12.10.2011

19. PPM - DAQ Alexander Enzenhöfer, VLVnT 2011, 12.10.2011 19 PMT - Data to coastFPGA Hydrophone Acoustic sensor Main amplifier board ADC board designed by INFN Catania (commercial stereo ADC, 24 bits @ 192 kSps) ADC

20. Summary Different possibilities to realise acoustic calibration PPM allows for detailed studies on different devices under real conditions ECAP sensor concept shows good results in the laboratory and more sophisticated measurements are planned 20 Alexander Enzenhöfer, VLVnT 2011, 12.10.2011