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Dual acoustic GW detector : 

Dual acoustic GW detector On behalf of DUAL collaboration Michele Bignotto I.N.F.N. Padova www.pd.infn.it I.N.F.N. Firenze www.fi.infn.it I.F.N. Trento www.ifn.cnr.it

Dual: Main Concept: 

Measurement of differential deformations of two nested resonators Intermediate GW broadband Dual: Main Concept 5.0 kHz π Phase difference The inner resonator is driven below frequency The outer resonator is driven above resonance

Mode selection strategy: 

Mode selection strategy Bonaldi et al., Phys. Rev. D 68 102004 (2003) 2-D Quadrupolar filter: X=X1 +X3 –X2 –X4 Capacitive transduction design Large interrogation regions Geometrically based mode selection Reject high frequency resonant modes which do not carry any GW signal Bandwidth free from acoustic modes not sensitive to GW

Dual: Shh(): 

Dual: Shh() Mo Dual 16.4 ton height 2.3m 0.94m SiC Dual 62.2 ton height 3.0m 2.9m Q/T=2x108 K-1 Bonaldi et al. Phys. Rev. D 68 102004 (2003)

Transducers for Dual Detectors: 

Transducers for Dual Detectors Goals for mechanical amplifier “dual” dedicated: Broadband amplification up to 5.0 kHz The biggest displacement gain factor 1/ First internal resonance out of the working band Negligible intrinsic thermal noise Compliance Leverage type amplifier H.J. Paik, proceedings First AMALDI Conference (1995)

Transducers for Dual Detectors: Leverages: 

Transducers for Dual Detectors: Leverages Capacitive readout Electric Field Optic readout 3 Joints Fabry-Perot mirrors 4 paired joints Gain=1/α 90 mm

Transducers for Dual Detectors: F-P Leverage: 

We designed a test-oscillator that play the role of a general GW antenna: Transducers for Dual Detectors: F-P Leverage Material Al 7075 Geometrical Gain factor 1/=10 First Longitudinal mode at 2100 Hz Stiffness K=1.5 107 N/m Test-Oscillator: Material Al 7075 First Longitudinal mode at 1800 Hz Stiffness K=3.5 108 N/m Effective mass M=5.6 kg Rigid Lever Optimized by a parametric software

Opto-mechanical leverage:Thermal noise: 

Opto-mechanical leverage: Thermal noise ANSYS Prediction by using Fluctuation Dissipation Theorem T=300 K, Q=104, Al 7075, w0 =365 m Leverage behavior: scaling with 1/α 1/α

Mechanical measurements: 

Mechanical measurements Direct Gain = 1/α = Δy/ Δx Frequency shift Leverage behavior

Opto-mechanical leverage:Thermal noise measurement: 

Opto-mechanical leverage: Thermal noise measurement Vacuum Chamber ±50μK Polystyrene boxes Copper box ±1mK Heater mats

Slide11: 

Optimization: EnginSoft Software: modeFRONTIER Capacitive Leverage: M. Saraceni m.saraceni@enginsoft.it 9 Parameters optimization!

Slide12: 

Thermal noise FEM prediction Capacitive Leverage: Thermal noise E. Serra eserra@itc.it Mode contribution Clamped leverage Minimum at f0/51/2 f0: first mode

Slide13: 

Apparatus for High voltage study Capacitive Leverage: Voltage breakdown M. Bonaldi, F. Penasa, Trento Phys. Dept. Goal: 108 V/m Achieved: 107 V/m Measurement of V.B. of aluminum polished surfaces of cylindrical samples Linear vertical stage Two axis adjustment

Conclusions: 

Conclusions A first opto-mechanical leverage was mechanically characterized Now we will measure its thermal noise A capacitive leverage had been designed and optimized We want to increase its transduction efficiency by studying voltage breakdown on facing surfaces

Summary: 

Summary Wide Bandwith Dual Acoustic Detectors Transducers for Duals Leverage Optic Prototype Capacitive leverage study Conclusions

Slide16: 

Al 7075 Al 7075 Leverage+oscillator machined for measurements: Mechanical Isolator Piezo’s Shakers Accelerometers

Mechanical measurements: 

Mechanical measurements Inverse Gain = Δy/ Δx Frequency shift