virgo-material “macro” group m.punturo. virgo-mat2 virgo-mat components virgo-mat is composed by...
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Virgo-Material “macro” group
M.Punturo
VIRGO-MAT 2
VIRGO-MAT components
• Virgo-MAT is composed by three INFN groups– Firenze/Urbino
• M.Lorenzini, G.Losurdo, F. Martelli, F. Piergiovanni, F.Vetrano
– Perugia• P.Amico, C.Bernardini, L.Gammaitoni, F.Marchesoni, M.Punturo,
F.Travasso, H.Vocca
– Pisa• M. Al-Shourbagy, S.Bigotta, A.Di Lieto, L.Predolin, A.Toncelli,
M.Tonelli
VIRGO-MAT 3
M1 Activities• Advanced materials for mirror substrates
– Michelson-Morley ITF in Perugia (next slide)– Mechanical characterization of the VIRGO Mirror
substrates in Perugia and in the site (Vir-Not-Per-1390-263)– Measurement of substrates for future ITF
• CaF2 substrate (P. Amico et al, Rev.Sci.Instr. 73 (2002), 178-184)
• Monocrystalline Si substrate “Virgo like”
4
M1:Large substrate measurement facility
PZT
PHD
Vacuum Chamber @10-6 mbar
+
+15
-15
x
Hz few n
HV
HV
nm064.1
Locking electronics
Read-out electronics
Pusher
Hz
mL
1210
VIRGO-MAT 5
M2 ActivitiesAdvanced materials and techniques for resonant detectors
• “Support” role:– Long history in measurement of low losses materials– Several infrastructures to measure thermo-mechanical
properties of fibers in Perugia and Firenze, at room temperature and at low temperature (M5 task)
• Two “clamp free” loss angle measurement facilities
• One cryostat under completion
VIRGO-MAT 6
M4 activitiesDevelopment of low loss dielectric coatings for advanced detectors
• Fabry-Perot facility to measure directly thermal noise in thin membranes (see P.Amico report in T1 task)– Coating effect of thin membranes and small mirrors
• Facility to measure the Q of coated membranes realized under the EGO R&D program and delivered to Lyon
VIRGO-MAT 7
M5 activities
• R&D activities for next generation ITF suspension
• Realization of mono-crystalline fibers that could improve the suspension thermal noise at room temperature and at low temperature– Best candidate: silicon fibers/ribbons– Exotic cooling technique: anti-stokes fluorescence
VIRGO-MAT 8
Micro-Pulling-Down furnace in Pisa
VIRGO-MAT 9
Produced mono-crystalline fibers10/03/04 L 4 cm 12/03/04 L 13 cm
16/03/04 L 13 cm
18/03/04 L 17 cm
22/03/04 L 11 cm
25/03/04 L 21 cm
VIRGO-MAT 10
Evaluation of the thermo-elastic contribution
7.026765 104
3.877602 1010
thSiO2 x 300( )
thSi x 300( )
thAl2O3 x 300( )
thSiO2 x 200( )
thSi x 200( )
thAl2O3 x 200( )
10000.1 x0.1 1 10 100 1 10
31 10
10
1 109
1 108
1 107
1 106
1 105
1 104
1 103
Sapphire @ 300K
Sapphire @ 200K
FS @ 300K
Si @ 300K Si @ 200K
FS @ 200K
Thermoelastic loss angle
VIRGO-MAT 11
Particular behavior of Si
0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300-1x10-6
0
1x10-6
2x10-6
3x10-6
4x10-6
5x10-6
0
1000
2000
3000
4000
5000
6000
The
rma
l exp
ansi
on c
oeffi
cie
nt [
K-1]
Temperature [K]
The
rma
l Co
nduc
tivity
[W
m-1 K
-1]
Crystalline Silicon
VIRGO-MAT 12
Magic temperature
105
1011
thSiO2 x 100( )
thSi x 100( )
thSi x 117( )
100000.1 x0.1 1 10 100 1 10
31 10
41 10
11
1 1010
1 109
1 108
1 107
1 106
1 105
FS @ 100K
Si @ 117K
Si @ 100K
VIRGO-MAT 13
How to cool locally?• It is important to cool locally the flexural point
– Cold finger• Easy to implement
• Commercial
• Liquid N2 is enough
• Noisy
– Anti-stokes fluorescence• High difficulties
• Low (?) efficiency
• And the noise?
VIRGO-MAT 14
Anti-Stokes Cooling• To evaluate the temperature distribution along the wire, we
must take in account the thermal conduction/dissipation processes
Laser
T0=300K
T0=300K
Si fiber200m diameter700 mm height
SiO2 clamp, 35mm diameter
VIRGO-MAT 15
ec x( )
x100 200 300
0
0.05
0.1
Thermal conduction mechanisms• Usual thermo-dynamical sign definition• Anti-stokes cooling
Laser
T0=300K
T0=300K
dtPTedq lasas )(
TeT
Te
0)(
0 is the temperature where the efficiency goes to zeroFor ZPLAN we have
0018.0
2595
480
M.T.Murtagh, J.of Non-Crystalline solids 253 (1999) 50-57
VIRGO-MAT 16
Thermal conduction• Conduction law
qk
qk
dtdl
SdTTkdqk
• For each small section we can discretize:
dtdl
STTTTTkdqdqdq jjjjjokikk 11,,
IR Radiation dtSTTTdq
dtSTTTdq
ljjSBr
lSBr
03
03
1
1067.5 8
SB
VIRGO-MAT 17
Differential Equation• The differential equation is, where T=T(t,y)
dtSyTTyTdl
Sdy
y
TyTklPTe
mcTydttTydT lSBlas
Si
03
0 )(1
,
• It is a “bordello” then, I adopted a numerical solution
300
117.517117
T0 t
TNstep 1
2t
TNstep t
Ntime dt0 t dt0 50 100 150 200 250 300
100
150
200
250
300 300
50
Ti
Ntime
10
Ti
5 Ntime
10
Ti Ntime
Nstep 1( ) L0 i L0 0.1 0.2 0.3 0.4 0.5 0.6
50
100
150
200
250
300
VIRGO-MAT 18
Temperature distribution
-0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7100
150
200
250
300
Te
mp
era
ture
[K]
Position [m]
T T
1(y)=300-(300-116.928)exp(-8.28 y)
T2(y)= A + B
1y + B
2y2 + B
3y3 + B
4y4
Parameter Value Error-------------------------------------------A 113.52815 1.67763B1 1285.48793 36.89706B2 -3163.21177 234.42451B3 3219.72231 536.33065B4 -1100.03542 399.89429--------------------------------------------
It is not linear and the noise evaluation must take in account it
VIRGO-MAT 19
104
109
P f( )
100000.1 f0.1 1 10 100 1 10
31 10
41 10
9
1 108
1 107
1 106
1 105
1 104
Noise contribution due to optical cooling
• Fundamentally, the optical cooling can introduce a length noise in the interferometer through the cooling laser power fluctuation coupled with the fiber length
• The laser power fluctuation causes a wire length fluctuation filtered by– Thermal conduction process
– Vertical spring behavior of the suspension wire
fP Laser power fluctuation
Optical cooling efficiency
Poc Subtracted power fluctuation
TeT
Te
0)(
VIRGO-MAT 20
… noise evaluation 2
• The integral length fluctuation is given by:
f
ff Tcm
fPTeLfTL
,
• Where Tf is the temperature of the (cooled) flexural point, m the mass of the wire, c(T) is the specific heat and the average expansion coefficient is:
yL
eyTdyyTL
28.8
0
)928.116300(300)(1
• Taking in account also the filtering effect of the thermal conduction:
f
f
c
f Tcm
fPTeL
ffTL
21
1,
cmS
Lc
1
VIRGO-MAT 21
… noise evaluation 3• Taking into account that the loaded wire acts like a spring:
22
0
2220
202
0 0)(
LyLyy
• Considering the (minimal) Vertical to Horizontal coupling:
1 10 100 100010-25
10-24
10-23
10-22
10-21
10-20
10-19
10-18
h(f
) [1
/sq
rt(H
z)]
Frequency [Hz]
Current Virgo Pendulum thermal noise Steel Wire Creep Optical Cooling on high k Pend.Th.Noise FS suspension
VIRGO-MAT 22
M5-Cx: “Classical” cryogenic design • Drawing of a cryogenic payload for the EGO-VIRGO cryogenic facility
– G.Cella, A.Giazotto, R.Passquieti, M.Punturo, F.Richard
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