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New materials for DUAL: the LNL activity

New materials for DUAL: the LNL activity. Dual detector : Best material parameters. Two different materials ‘A’ and ‘B’ with two different Young modulus Y and density r Sensitivity curve optimized in the same frequency window QL readout Toroidal shape No thermal noise.

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New materials for DUAL: the LNL activity

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  1. New materials for DUAL: the LNL activity

  2. Dual detector : Best material parameters • Two different materials ‘A’ and ‘B’ with two different Young modulus Y and density r • Sensitivity curve optimized in the same frequency window • QL readout • Toroidal shape • No thermal noise Strain PSD of material A,B Young modulus of mat. A,B Density of material A,B

  3. Dual detector : Candidate Materials • Minimize sensitivity curve i.e. maximize • Minimize thermal noise -Diamond 163 ? expensive -Silicon carbide 27 Not well known available in large size -Berillium 24 <106 expensive -Sapphire 13 108 expensive+need bonding -Molibdenum 6.8 107available in large size -Silicon 4.4 >108 need bonding -others ? (i.e. Alumina (17), MoCu (), CuBe) Red= Material under investigation

  4. Sintered silicon carbide: results • Cantilevers of different thickness (0.3-0.5 mm) and lenght (5-10 cm) • Both optical lever and capacitive readout Similar results in E.K. Hu et al. Phys Lett. A 157, 209 (1991) -> Annealing should improve the Q

  5. Sintered silicon carbide: results • Cantilevers of different thickness (0.3-0.5 mm) and lenght (5-10 cm) • Both optical lever and capacitive readout Similar results in E.K. Hu et al. Phys Lett. A 157, 209 (1991) -> Annealing should improve the Q -->Seem not very much

  6. Infiltrated silicon carbide C-SiC: results • Measured samples: two cantilever of different thickness and lenght from Cesic (Germany) • Different Carbon matrices • Capacitive readout Not Annealed Annealed • Best achieved loss angle 2x10-6 • Annealing did’nt improve the quality factor

  7. Silicon samples: bonding research A Silicon Wafer bonder is now availabe at the Mt-Lab in Trento Machine capabilities • Ready made for many bond proccesses (Anodic bonding, Eutetic bonding,Adhesive bonding,Fusion bonding,Thermocompression bonding) • Wafer diameter 100 mm • Stack thickness 6 mm

  8. Silicon samples: bonding loss angle Silicon wafer Bonding Layer Disk loss angle Bonded silicon disk h=0.9 mm d=100 nm Ansys Analysis

  9. Si disk suspension set-up SS spring SS piston Si Disk Sapphire balls F=1mm Al Not in scale cross section Set up #1 silicon bulk wet etching Silicon <100> TMAH 175 mm deep pyramid hole, with square opening 500 mm side <111> crystal plane side wall

  10. Si disk suspension set-up SS piston SS spring Si Disk Sapphire balls F=1mm Al Not in scale cross section Set up #2 Hole about 300 mm in diameter , Milled using dentist’s tools

  11. Si disk displacement Readout Achieved sensitivity 10-8 -10-9 m Quadrant photodiode Laser Observed warm-up effects at low temperature ! Thus not ideal for ultracryogenic operations

  12. Si disk displacement Readout Vbias Vout Rotate View Capacitive readout

  13. Si disk: capacitive redout The comb capacitor capacitance value C(x) is a function of the distance (gap+Dx) between them and the opposite dielectric plate Readout sensitivity High sensitivity require • Small gap • Low parasitic capacitance (Cpar) • Low noise voltage preamplifiers (SQUID amplifer can improve sensitivity very much) Vbias C(x) Achieved Sensitivity during run #1 (Vbias=60 Volt, gap= 0.1 mm)

  14. Si disk: first cryogenic run set-up • Si <100> oriented Boron doped • Disk diameter 4 inch • Thickness 0.5 mm F=2mm SS piston Si disk Sapphire balls Misalignement problem Adopted suspension (not optimized) set-up

  15. Si disk: first cryogenic run results

  16. First Si Disk cryogenic run: Quality factor limitations • The contribution of thermoelastic damping and surface losses at 4.2 K should be less thenF<10-8 • We are presumably dominated by suspension losses and/or sample microfracture induced by manufacturing the central hole • However for this specific run gas damping should play a relelvant role because we had a cold leak Christian’s Model Bao et al. Model (sqeezed film damping ) Comb Capacitor Even worse using true gas dynamic models and outgasing

  17. Conclusions • •SiC is very interesting for its high sound velocity, but the sintered and the infiltrated silicon carbide, that can be fabricated in large size as required for the Dual detector, show at low temperature a quality factor that is at least 2 order of magnitude lower than the required value. The quality factor of monocristalline SiC should be better but in this case we have to develop low losses bonding procedures and take care of the cost. • Monocristalline Silicon is also a candidate material but it is not available at the required size. We plan to measure the Si bond losses to evaluate if a big elastic body can be obtained bonding togheter smaller pieces without affecting the overall Q fator • Molybdenum is the best candidate material for the Dual detector however we are considering other material considering other materials as MoCu, pure Alumina, CuAl

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