Sapphire Test MassesACIGA/UWA

•High lights of research at UWA

•Alternative approach to suspensions

•High power test facility

•Cryogenic applications

Mark Baker*,Fetah Benabid*, David Blair Ju Li Darren PagetMitsuru Taniwaki*Colin Taylor

LIGO-G010166-00-Z

Summary of work in UWA (ACIGA) on Sapphire

in collaboration withLIGO: B. Barish, S. Witcomb, D. Reitze, A. Alexandrovski

VIRGO: J. Mackowski, A. Brillet, C. Man, F. Bondu, F. Cleva, V. Loriette, C. Boccara

Year system results Ref

1996 Thermal expansion CryogenicSapphire cavity =210-10 (5K)

IEEE Trans.Instrum. Meas.46, 188 (1997)

1996 AbsorptionVIRGO, Paris

3ppm/cm (one sample)20-50ppm/cm typical

Opt. Mat.8, 233 (1997)

1997 Sapphire mirrorsCSIRO, polishingVIRGO, Lyon, coating

Roughness < 0.1nm;Coating scatter 1ppm;Surface scatter 13ppm

Appl. Opt.36, 337 (1997)

1998Q-factorAcoustic Loss &suspension systems

Nb microcantilever suspensionsLIGO, VIRGO & UWAsamples

Q~5107

Quantitative losspredictions confirmed

Phys. Lett. A,246, 37 (1998)

1998 Birefringencehomogeniety

PEM Birefringence mapping <0.03 /cm Phys. Lett. A237, 337 (1998)

1999 Rayleigh scattering Imaging Scatterometer 12.6ppm Opt. Commun.167, 7 (1999)

2000 x-ray inducedabsorptionre-annealing

VIRGO, ParisPartially reversed byannealing

J. Phys. D33, 589 (2000)

History of CSI Whiteand Hemex-Ultrasapphire samples

EXPERIMENT RESULTS

Hemex Ultra

abs(ppm/cm)

55+/-4

Al (50.98%)O (47.8%)Si (0.615)P (0.055%)Ca (0.038)Signature(<10-4)of :Cu, S, Mo, F.

abs(ppm/cm)

~140(Stanford)

~80(UWA)

after annealing

24(UWA)

Csi-White

abs(ppm/cm)3. 3+/- 0.5

Al(56.6%) O (43%)Si (0.346)

Signature(<10-4) of:Th, Cu, Ca, S, Mo

abs(ppm/cm)

~120(Stanford)

~64

(UWA)

after annealing

40(UWA)

Photothermalabsorption

Photothermalabsorption

XRF

spectroscopy

Photothermalabsorption scan

Annealing

Photothermal Absorption measurement results

Samples Absorption(ppm/cm)

Hemex Ultra(101020)

50->70->40 X-rayed->reannealed

CSI white(101020)

3->100->20 X-rayed->reannealed

CSI standard (A)(30100)

45->55 Localised exposure to x-ray

CSI white (C)(30100)

43

CSI white (D)(30100)

42

Russian Czochralski grown(30100)

90

Absorption MapCSI Standard- #A

(plan z=10mm)

- 15 - 10 - 5 0 5 10 15

Horizontal positionHstepL- 15

- 10

- 5

0

5

10

15

lacitreV

noitis

opHpetsL

<1.3

<4.1

<6.9

<9.7

<12.5

<15.2

<18.

<20.8

<23.6

<26.3

<29.1

<31.9

<34.7

<37.5

<40.2

<43.

<45.8

<48.6

<51.4

<54.1

>54.1

ppmcm

Xray-irradiated spot Max=55.6ppm/cm

min=37ppm/cmaver=45.2 ppm/cmSTDdev=3.2

Annealing Effect on the Absorption in the UV Range (F centers range)

200 300 400 500 600 700 800 900 1000 1100 1200

1E-4

1E-3

0.01

0.1

1

AB

SOR

PTIO

N C

OEF

FIC

IEN

T (c

m-1

)

WAVELENGTH (nm)

1E-4

1E-3

0.01

0.1

1

483 nm409 nm

568 nm band

298 nm band

364 nm band

1120 nm band

F2

+

921nmband

784 nm band

[Ti3+

][Ti4+

]

F+

F2and/or [Ti

3+][Ti

4+]

(~260 nm band)

F Hemex Ultra Csi White

200 250 300 3500.01

0.1

1

200 250 300 350

0.01

0.1

1

Dashed lines->Before annealingContinuous->After annealingred/Magenta->CSI-White sampleblue/Cyan->Hemex-Ultra sample

Annealing Effect on the Absorption in the IR Range

200 300 400 500 600 700 800 900 1000

1E-4

1E-3

0.01

0.1

1

AB

SOR

PTIO

N C

OE

FFIC

IEN

T (

cm-1)

WAVELENGTH (nm)

200 300 400 500 600 700 800 900 1000

1E-4

1E-3

0.01

0.1

1

F2

+

921nmband

[Ti3+

][Ti4+

]

F+

F2

F Hemex Ultra Csi White

800 900 1000

1E-4

1E-3

750 800 850 900 950 1000

1E-4

1E-3

Birefringence Phase Retardation (degree/ 10cm)

Contour Plot of Sapphire Hemex

Rayleigh Scattering measurements set-up

CCD

Ammeter

Calibrated photo-detector

La s

e r

Data treatment

Sample

D

D:pupil.: angle of observation: collection solid angleV: scattering volume

V=d.S

Rayleigh Scattering Measurement of Different Sapphire Samples

Sample sca @1064nm(ppm/cm)measured

sca @1064nm(ppm/cm)predicted

Hemex

(50100)

18.4

CSI standard (A)

(30100)

12.6

CSI standard (B)

(30100)

13.4

0.2

Fused silica I 11.7

Fused silica II 6.7 0.4

Microcantilever suspension study

Qcantilever~ 3105

Internal mode of cantilever control

Qsapphire ~ 5107

High pressure contact (plastic deformation) to achieve low loss

Internal Q of sapphire

Suspension System

niobium catherine wheel

cantilever

vacuum chamber

bottom stage (steel)

intermediate stage (brass)

steel ball

sapphire sample

aluminium platform

mechanical exciter

transducer

HEMEX sapphire sample (Cristal Systems)

100 mm

50 mmlongitudinal frequency = 53.4 kHz

The Loss of Test Mass due to the Coupling to the Internal Resonances of Supporting structure

104

105

106

107

108

109

40 42 44 46 48 50 52 54 56

as-machined

annealed

annealed & etched

exp as machined

exp annealed

exp etched (2nd-)

Q o

f H

EM

EX

sap

phire

sam

ple

internal frequency of catherine wheel (kHz)

Test of monolithic Nb pendulum

•Annealed & etched flexure1mm10mm 60m

•Material Q ~2 105

•Pendulum Q ~ 3 107

(3.4 kg, pressure corrected)

0.001

0.01

0 10 20 30 40 50 60 70

y = 0.0086383 * e (̂-0.0017274x) R= 0.98176

Time (hr)

f=1.26 Hz

Q=8.2x106

Ring down of a Nb monolithic pendulum

Material Q-factor Q0= 2 x 105

(gas damping corrected)

Dovetail Suspension

•Tensile equivalent to microcantilever •Low loss flexure included•Low mass reduces cantilever loss contribution

--predicted Qint>108

•Modular easily replaceable suspension element•Exceptional cryogenic performance predicted•Need to confirm sapphire Q after cutting

2001 program on suspension:measure internal mode Q of sapphire

with Nb flexure suspension

Configuration 1

•Suspension losses minimised--coupling factor: 0.1~0.3

•Dovetail groove near stress antinode--possible Q-degradation

•Note: dovetail groove is very smallcf, Braginsky’s sapphire bar with horns

excitation

Configuration 2

•Suspension loss maximised--coupling factor =1

•Low stress at dovetail joint

Cryogenic Applications of

Dovetail Flexure

•Thermal conductivity of niobium at 10K:

90Wm-1K-1

•Expected thermal resistance:

~ 10K/W

•Niobium is an exceptional material

for high thermal conductivity isolation

and suspension stages

ACIGA High Power Test FacilityResearch Program

2001 Implement 10m mode cleanerLow power evaluation of isolator/suspension pairs

Low residual motion isolators with pre-isolationNiobium flexure suspensions

2002 Adelaide University 5-10W laser.PR mirror + South Arm input mirrorBaseline data:

Lock acquisition Thermal lensing Optical degradation

2003 80m high power test cavity100W Adelaide University laser Power recycling cavity + 80m arm cavity

Lock acquisition under high radiation pressureThermal lensingOptical degradation

2004 East arm cavity-2005 Implement interferometer

for high power noise evaluation

High Power Testing Facility at Gingin, WA

Interferometer arm for noise measurements(2004-2005)

80m high power test cavity (2003)

10m Mode cleaner (2001)

Injection locked laser0.5W (2001), 5W (2002), 100W (2004)

Pre-stabilisationcavity (2001)

Beam expander

Input mirror(2002)

End mirror (2003)

Power recycling(2002)