Sapphire Test Masses ACIGA/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 Paget Mitsuru Taniwaki* Colin Taylor LIGO-G Z
Summary of work in UWA (ACIGA) on Sapphire in collaboration with LIGO: B. Barish, S. Witcomb, D. Reitze, A. Alexandrovski VIRGO: J. Mackowski, A. Brillet, C. Man, F. Bondu, F. Cleva, V. Loriette, C. Boccara
History of CSI Whiteand Hemex-Ultra sapphire samples
Photothermal Absorption measurement results
Absorption Map CSI Standard- #A (plan z=10mm) Xray-irradiated spot Max=55.6ppm/cm min=37ppm/cm aver=45.2 ppm/cm STDdev=3.2
Annealing Effect on the Absorption in the UV Range (F centers range)
Annealing Effect on the Absorption in the IR Range
Birefringence Phase Retardation (degree/ 10cm) Contour Plot of Sapphire Hemex
Rayleigh Scattering measurements set-up CCD Ammeter Calibrated photo-detector Laser Data treatment Sample D D:pupil. : angle of observation : collection solid angle V: scattering volume V=d.S
Rayleigh Scattering Measurement of Different Sapphire Samples
Microcantilever suspension study Q cantilever ~ 3 10 5 Internal mode of cantilever control Q sapphire ~ 5 10 7 High pressure contact (plastic deformation) to achieve low loss
Internal Q of sapphire
The Loss of Test Mass due to the Coupling to the Internal Resonances of Supporting structure
Test of monolithic Nb pendulum Annealed & etched flexure 1mm 10mm 60 m Material Q ~2 10 5 Pendulum Q ~ 3 10 7 (3.4 kg, pressure corrected)
Ring down of a Nb monolithic pendulum Material Q-factor Q 0 = 2 x 10 5 (gas damping corrected)
Dovetail Suspension Tensile equivalent to microcantilever Low loss flexure included Low mass reduces cantilever loss contribution --predicted Q int >10 8 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 small cf, 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 -1 K -1 Expected thermal resistance: ~ 10K/W Niobium is an exceptional material for high thermal conductivity isolation and suspension stages
ACIGA High Power Test Facility Research Program 2001Implement 10m mode cleaner Low power evaluation of isolator/suspension pairs Low residual motion isolators with pre-isolation Niobium flexure suspensions 2002Adelaide University 5-10W laser. PR mirror + South Arm input mirror Baseline data: Lock acquisition Thermal lensing Optical degradation m high power test cavity 100W Adelaide University laser Power recycling cavity + 80m arm cavity Lock acquisition under high radiation pressure Thermal lensing Optical degradation 2004 East arm cavity -2005Implement interferometer for high power noise evaluation
High Power Testing Facility at Gingin, WA