francesco cottone infn & physics departments of perugia, pisa, florence (collaboration work...
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Francesco Cottone
INFN & Physics Departments of Perugia, Pisa, Florence
(Collaboration Work under VIRGO Project)
Thermomechanical properties of silicon fibers for 3rd GW detectors
ILIAS GW Meeting – October 25th, 2005Palma de Mallorca, Spain
Francesco Cottone ILIAS GW Meeting - 25 October 2005
Outlines
Requirements for low thermal noise Suspension wire
Silicon thermo-mechanical properties
Experimental setup
Measurements of thermo-mechanical parameters at Room and low Temperature
Conclusions
Francesco Cottone ILIAS GW Meeting - 25 October 2005
Requirements for low thermal noise Suspension wire
Low loss angle φ High tensile strength TB High thermal conductivity Low thermal expansion
coefficient
Horizontal displacement power
spectrum
Wire length
Number of wires
Mirror mass
Tensile strength
LOSS ANGLE
Francesco Cottone ILIAS GW Meeting - 25 October 2005
Thermo-elastic Loss Angle:Thermo-elastic Loss Angle:Why crystalline Si for future GW detectors?Why crystalline Si for future GW detectors?
1 10 100 1000 1000010-8
10-7
10-6
10-5
10-4
10-3
10-8
10-7
10-6
10-5
10-4
10-3
C85 SiO
2
Si GSGG SiO
2 cris.
YAG
( f )
Frequency f (Hz)
2)(1)(
f
ffth
vc
TE 2
Francesco Cottone ILIAS GW Meeting - 25 October 2005
Thermomechanical Properties of Thermomechanical Properties of Crystalline SiliconCrystalline Silicon
Low thermal expansioncoefficient α That expected
to vanish at about 17 K and 123 K
Crystalline silicon is agood candidate thanks to its high thermal conductivity (at 300K) = 1.48 × 10^2Wm−1
K−1)
Huge Peak between 20-
30K
Francesco Cottone ILIAS GW Meeting - 25 October 2005
Thermomechanical Properties of Thermomechanical Properties of Crystalline SiliconCrystalline Silicon
Amplitude of the linear thermoelastic loss angle Vs
Temperature
Expected temperature dependence of the
thermoelastic peak frequency
Francesco Cottone ILIAS GW Meeting - 25 October 2005
Production of Silicon Fibers (Pisa groupProduction of Silicon Fibers (Pisa group))
Crucible
After heater
Grown fiber
RF coil
Seed Crystal
melt
Insulating shields
μ-pulling down Technique
Francesco Cottone ILIAS GW Meeting - 25 October 2005
Cryogenic Experimental SetupCryogenic Experimental Setup (Perugia Lab) (Perugia Lab)
Clamping system
Fiber
Copper block and conduction plate to realize thermal link
steel alloy spring
Shadow meter
HV excitatorHe Laser
lens
Francesco Cottone ILIAS GW Meeting - 25 October 2005
Experimental results at Room andExperimental results at Room and Low Temperature Low Temperature
2n )5.0(
1n )597.0()(
8 2
2
2nL
dYfn
Resonance frequencies modes
The fiber has roughtly elliptical section apporximated with two
circular sections with 2 diameters d1 and d2 that can be deduced
from each mode
md
md
168.256
126.208
2
1
Free lenght=111.5 mm
diameter 242 m
Francesco Cottone ILIAS GW Meeting - 25 October 2005
Experimental results at Room andExperimental results at Room and Low Temperature Low Temperature
50 100 150 200 250 300-0,002
0,000
0,002
0,004
0,006
0,008
0,010
Experimental Data Model fit <100> prediction <110> prediction <111> prediction
E(0) = (151.43±0.02) GPaB = (15.1±1.7 MPa/KT
0 = (324±33) K
E/E
Temperature [K]
iN
n roomn
roomnn
room
room
Tf
TfTf
NTE
TETE mod
12
22
)(
)()(1
)(
)()(
Young Modulus Vs Temperature Relative resonance frequency variation
50 100 150 200 250 300
0,001
0,002
0,003
0,004
0,005
f/f
Temperature [K]
f(T=291)=3620 Hz f(T=291)=2715 Hz f(T=291)=2909 Hz
Wachtman et al., Phys. Rev. 122 (1961)
T
T
BTeEE0
0
Francesco Cottone ILIAS GW Meeting - 25 October 2005
Experimental results at Room andExperimental results at Room and Low Temperature Low Temperature
Loss Angle at Room Temperature Vs Frequency (Firenze group)
Free lenght=278 mmdiameter 574 m
Free lenght=111.5 mm
diameter 242 m
Francesco Cottone ILIAS GW Meeting - 25 October 2005
Experimental results at Room andExperimental results at Room and Low Temperature Low Temperature
40 80 120 160 200 240 280 32010-9
10-8
10-7
10-6
10-5
10-4
Loss
Ang
le
Temperature [K]
F3620 F2715 F2909 F6680 Phi Teo (6680Hz)
10 100 1000 10000
10-7
10-6
10-5
10-4
10-3
Lo
ss A
ng
le
Frequency [Hz]
T =291K T =220K T =110K teorica a T=291K
Loss angle vs temperature Loss angle vs frequency
Loss Angle at low Temperature (Perugia group)Excess losses?
Francesco Cottone ILIAS GW Meeting - 25 October 2005
The µ-pulling down technique and the etching procedure permit to realize fibers having the appropriate size
At room temperature, the fibres confirm the expected properties: the high thermal conductivity of the Silicon pushes the thermo–
elastic dissipation peak at high frequency
At low temperature (about 120 K) the reduction of the thermo–elastic dissipation, due to the thermal expansion coefficient behavior, is hidden by the presence of other dissipation mechanisms, probably related to bulk and surface defects.
ConclusionsConclusions
Francesco Cottone ILIAS GW Meeting - 25 October 2005
Better control of the diameter regularity and crystal orientation must be developed
Improving of the clamping system to realize more robust blocking to reduce extra losses (in progress)
Necessity to investigate the behavior of a crystalline Silicon fibres suspension at really cryogenic temperature
At about 5–20 K the thermo–elastic dissipation will be negligible thanks both to the thermal expansion coefficient vanishing and to the direct temperature dependence of the thermo–elastic strength Δ.
Next stepsNext steps