Diapositiva 1

1
Investigation on annealing effect in a Suprasil
sample and loss measurements in silicon samples
Elisabetta Cesarini a,b), Gianpietro Cagnoli
a,c), Enrico Campagna a,d), Matteo Lorenzini
a,b), Giovanni Losurdo a), Filippo Martelli a,d),
Francesco Piergiovanni a,d) , Flavio Vetrano
a,d)

• INFN Sez. Firenze
• Università di Firenze (Dip. Astronomia e Scienza
  dello Spazio)
• University of Glasgow
• Università di Urbino

4 ILIAS-GWA Annual Meeting - Tubingen (D),
October 8-9, 2007
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Summary
Last ILIAS-GW meeting 26-27 October 2006 we
presented Q measurement facility Innovative
nodal suspension, designed and realized (GeNS)

• Now
• We are measuring the loss angle of different
  interesting materials
• Herasil
• Suprasil (annealed sample, that we are
  investigating with surface analysis)
• Silicon (we are trying to calculate the
  thermoelastic contribution to fit our
  measurements)

4 ILIAS-GWA Annual Meeting - Tubingen (D),
October 8-9, 2007
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Dissipation measurements on Suprasil samples
SAMPLE Suprasil 311 disk 75x3 mm Sapphire sphere
D 4.75 mm
Contact surface (radius 20 mm)
Q does not depend on suspension centering, in a
single suspension, in the region between -30µm e
30µm with a contact surface of 20 µm
3469 Hz 1 Butterfly mode
7890 Hz 2 Butterfly mode
4 ILIAS-GWA Annual Meeting - Tubingen (D),
October 8-9, 2007
4 ILIAS-GWA Annual Meeting - Tubingen (D),
October 8-9, 2007
4
Dissipation measurements on Suprasil samples
Measurement after the annealing Q(3469Hz)2107

• Anneal in air (suggested by S.Penn)
• Raise the oven temperature to the annealing point
  (1120C for Suprasil)
• Cool down to the strain temperature (1025C for
  Suprasil) with a rate of about 10 degrees per
  hour
• -Turn off the oven and wait for cool down in 24
  hours

First measurement Q(3469Hz)2.7106
it is smaller by a factor two!!
4 ILIAS-GWA Annual Meeting - Tubingen (D),
October 8-9, 2007
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Annealing study
Is the Q value increasing due to an internal or
a surface effect?
Surface Analysis In collaboration with INFN
sezione Genova and Università di Genova
Ellipsometry and XPS
still under investigation
counts/s
Binding Energy (eV)
4 ILIAS-GWA Annual Meeting - Tubingen (D),
October 8-9, 2007
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Dissipation measurements on silicon samples
RESULT SUMMARY

• Samples
• 75x1 mm
• 75x3 mm sapphire sphere (d4.76 mm)
• 75x10 mm sapphire sphere (d15-20 mm)

Bad reproducibility of measurements in different
suspensions
CLEANING PROCEDURE We have to work in a clean
room!!!
4 ILIAS-GWA Annual Meeting - Tubingen (D),
October 8-9, 2007
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Dissipation measurements on silicon samples
Taking into account only the maximum values
WHAT IS HAPPENING?
4 ILIAS-GWA Annual Meeting - Tubingen (D),
October 8-9, 2007
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Thermoelastic contribution calculation
Thermoelastic contribution for a disk of finite
dimensions

• Previous calculations
• - F. Bondu, P. Hello, J.Y. Vinet, Phys. Lett A
  246 (1998) 227
• Y.T. Liu and K.S. Thorne, Phys. Rev. D 62 (2000)
  122002
• V. B. Braginsky, M.L. Gorodetski, S.P.
  Vyatchanin, Phys Lett. A 264 (1999) 1

How to solve the problem of the sources in a
non-adiabatic condition for a cristalline
material?
ADIABATIC APPROXIMATION The DT is not influenced
by heat fluxes
We want to simulate the vibrations of the disk
with ANSYS, then take the time derivative of the
deformations and put them in the diffusion heat
equation.
work in progress
We want to calculate exactly the thermoelastic
contribution without any approximation
What is our idea?
4 ILIAS-GWA Annual Meeting - Tubingen (D),
October 8-9, 2007
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Next work

1. New surface analysis after the annealing, trying
   to understand if the produced effect is internal
   or superficial.
2. Calculation of the thermoelastic contribution in
   silicon disks, without any approximation.
3. New loss measurements of the silicon samples with
   different thickness (in collaboration with Jena
   University).
4. Measurements of mechanical properties of coated
   samples suitably altered or damaged.

4 ILIAS-GWA Annual Meeting - Tubingen (D),
October 8-9, 2007
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Thanks for your attention