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Acoustic Calibration for the KM3NeT Pre-Production Module

Acoustic Calibration for the KM3NeT Pre-Production Module. Alexander Enzenhöfer on behalf of the KM3NeT consortium VLV n T 2011 Erlangen, 12.10. – 14.10.2011. Why and how to do acoustic calibration. Why acoustic calibration?. Deep sea as highly dynamic environment:

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Acoustic Calibration for the KM3NeT Pre-Production Module

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

  2. Why and how to do acoustic calibration 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 mfor light, ~1 km for sound) • Low cost with possibility to use commercial systems 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 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 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, … Alexander Enzenhöfer, VLVnT 2011, 12.10.2011

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

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

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

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

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

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

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

  20. Summary • Different possibilities to realiseacoustic 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 Alexander Enzenhöfer, VLVnT 2011, 12.10.2011

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