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Workshop on Piezoceramics for Acoustic Detection - Simulation & Measurement Studies

Explore calibration sources, displacement simulations, interferometer measurements, and piezoelectric effect in acoustic detection technology. Understand impedance and signal production in water for precise measurements. Study direction characteristics and equivalent circuit diagrams for piezos.

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Workshop on Piezoceramics for Acoustic Detection - Simulation & Measurement Studies

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  1. International ARENA Workshop at DESY, Zeuthen May 2005 Measurements and Simulation Studies of Piezoceramics for Acoustic Detection Karsten Salomon Universität Erlangen-Nürnberg

  2. Motivation • Development and simulation of calibration sources for acoustic detection • Simulation of detector devices • Understanding of the whole system emitter to receiver (finding the transfer functions) K. Salomon, Universität Erlangen-Nürnberg International ARENA Workshop, May 2005

  3. Sources for Calibration for Acoustic Particle Detection Electric bulbs Heated wires Laser Piezos K. Salomon, Universität Erlangen-Nürnberg International ARENA Workshop, May 2005

  4. Piezoelectric Effect • Equation of motion of piezos is complicated - coupled Partial Differential Equations (PDE) of an anisotropic material: • Hooke’s law + electrical coupling • Gauss law + mechanical coupling • Finite Element Method chosen to solve these PDE K. Salomon, Universität Erlangen-Nürnberg International ARENA Workshop, May 2005

  5. Displacement • Motivation: Calibration of sound source to measure the sensitivity of the hydrophone • Simulation: Displacement of a piezo disc due to electrical voltage is simulated for different frequencies using CAPA K. Salomon, Universität Erlangen-Nürnberg International ARENA Workshop, May 2005

  6. Schematic of the Interferometer • Measurement: Direct measurement of the displacement with a self built fibre coupled interferometer • Multiple reflections between piezo and fibre ending K. Salomon, Universität Erlangen-Nürnberg International ARENA Workshop, May 2005

  7. 2cm Setup of the Interferometer K. Salomon, Universität Erlangen-Nürnberg International ARENA Workshop, May 2005

  8. dx Photodiode Voltage (V) dUPhoto -/8 0 /8 Actuator Voltage (V) Calibration of the Interferometer • Description possible with geometric series • dU proportional dx • Calibration before each measurement • Photodiode voltage proportional to intensity • Precision of ~0.1nm K. Salomon, Universität Erlangen-Nürnberg International ARENA Workshop, May 2005

  9. Displacement - Results • Measurement: white noise applied to Piezos • Simulation: Finite Element Method • Eigenfrequencies -->no flat frequency response K. Salomon, Universität Erlangen-Nürnberg International ARENA Workshop, May 2005

  10. Sending Signals with the Piezo • Frequency response -> response to arbitrary signal • As a source for calibration a pressure signal is needed • How does the movement of the piezo result in a defined pressure signal? • Small excursion: signal production in water K. Salomon, Universität Erlangen-Nürnberg International ARENA Workshop, May 2005

  11. Signal Production in Water • Signal propagation in water is described with a wave equation • If the sent wavelength is larger than the dimension of the transmitter, then: • Change in volume dVA dx • Equation for pressure: • Displacement of piezo is proportional to the applied voltage • Outside resonances, the second derivative of the applied voltage will be sent K. Salomon, Universität Erlangen-Nürnberg International ARENA Workshop, May 2005

  12. Direction Characteristics:Simulation and Measurement • Simulation of a piezo disc R=7.5mm H=5mm • Coupling of the piezo displacement to water • Acoustic field after 20 µs when applying a 20kHz sine: K. Salomon, Universität Erlangen-Nürnberg International ARENA Workshop, May 2005

  13. Direction Characteristics:Simulation and Measurement Simulation Measurement K. Salomon, Universität Erlangen-Nürnberg International ARENA Workshop, May 2005

  14. Impedance of the Piezo: Simulation and Measurement • Motivation: • Understand electrical properties of the piezo • Calculate parameters for equivalent circuit diagram • Simulation • Apply charge pulse to the piezo. • Calculate voltage response. • Impedance is given in the frequency domain as: K. Salomon, Universität Erlangen-Nürnberg International ARENA Workshop, May 2005

  15. Impedance of the Piezo: Equivalent Circuit Diagram • First resonance and antiresonance of a piezo can be described with an equivalent circuit diagram: • L,C and R are equivalent to mass, stiffness and damping • With these parameters one gets a simplified piezo model K. Salomon, Universität Erlangen-Nürnberg International ARENA Workshop, May 2005

  16. Impedance of the Piezo: Simulation and Measurement • Far from resonances, the piezo acts like a capacitor Z~1/f K. Salomon, Universität Erlangen-Nürnberg International ARENA Workshop, May 2005

  17. Measurement: Displacement of a Commercial Hydrophone • Measurement with Laser Doppler Vibrometer K. Salomon, Universität Erlangen-Nürnberg International ARENA Workshop, May 2005

  18. Measurement: Displacement of a Commercial Hydrophone K. Salomon, Universität Erlangen-Nürnberg International ARENA Workshop, May 2005

  19. Summary • Summary: • Simulation in good agreement with measurement of piezos • Signal propagation in water described by simulation • Ideas how to calibrate hydrophones with impedance measurements • First steps how to calibrate hydrophones with displacement measurements K. Salomon, Universität Erlangen-Nürnberg International ARENA Workshop, May 2005

  20. Thanks for your attention K. Salomon, Universität Erlangen-Nürnberg International ARENA Workshop, May 2005

  21. The Finite Element Method • Numerical method to solve PDE with boundary value problems • Areas are discretisized into cells (finite elements) • Within a finite element characteristic functions are defined • Linear combinations of these functions then give possible solutions within an element K. Salomon, Universität Erlangen-Nürnberg International ARENA Workshop, May 2005

  22. Measurement: displacement of the HTI • Measurement with a Laser Doppler Velocimeter • Clearly seen a Peak at 57kHz but • Measurement: send different gaussians with HTI and receive with same type of HTI. Calculate Transferfunction: K. Salomon, Universität Erlangen-Nürnberg International ARENA Workshop, May 2005

  23. Measurement: displacement of the HTI • Explanaition: Additional damping due to water not completely known. K. Salomon, Universität Erlangen-Nürnberg International ARENA Workshop, May 2005

  24. Emulating a Neutrino Signal • Calculated neutrino signal in 400m distance following the thermoacoustic model for a 1PeV shower. • Send two times integrated neutrino signal K. Salomon, Universität Erlangen-Nürnberg International ARENA Workshop, May 2005

  25. Signal in frequency space Frequency response of the piezo Displacement using this Signal • But: Amplifiing the frequencies at the resonances • Send: • Simpler: Use a piezo with relatively flat frequency response Measurement Simulation K. Salomon, Universität Erlangen-Nürnberg International ARENA Workshop, May 2005

  26. Receiving the Bipolar Signal Signal Measured Second deriv. of signal K. Salomon, Universität Erlangen-Nürnberg International ARENA Workshop, May 2005

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