GEO600 Detector Status Harald Lück Max-Planck Institut für Gravitationsphysik Institut für Atom- und Molekülphysik, Uni Hannover

Worldwide Interferometer Network

Laser Optical Layout Michelson Interferometer Output Mode Cleaner Mode Cleaners 600m 10 W 5 W 1 W ~ 5 kW 10 kW at Beam Splitter ~50mW Light power (specs)

GEO 600 Sensitivity specs.

Laser Light Power (current) Michelson Interferometer Output Mode Cleaner Mode Cleaners 10W 1W 300W at Beam Splitter 2W2W ~10mW Mode Cleaners: Troughput 80% 72% Finesse Visibility 96% 92% 98.65% Power Recycling Cavity: Mode matching97% Finesse 450 Linewidth 270 Hz

Optical Layout Main Interferometer Mode Cleaner Laser Bench Output Bench

Slave Master Slave entrance to vacuum system Laser System Master Laser: Nd:YAG NPRO (non-planar ring oscillator) 1064 nm Slave Laser: Nd:YAG injection-locked ring cavity nm less than 5% in higher modes Additional Information: Talk: Wednesday 12:40 – 13:10 h Benno Willke Poster session: Tuesday 20:30 – 22:00 h

GEO Triple Pendulum Suspension

Thermal Noise Issues  Monolithic Suspension Silicate (Hydroxy- Catalysis) Bonding Weld

Length and Frequency Control Michelson Interferometer Output Mode Cleaner Laser Mode Cleaners 25 MHz 13 MHz 37 MHz Laser Frequency Stabilisation: no rigid reference cavity laser is directly stabilised to suspended cavities 3 sequential Pound- Drever-Hall control loops common mode of the Power-Recycled Michelson serves as frequency reference

Mode Cleaners Output Mode Cleaner Michelson Length Control Michelson Interferometer Laser 15 MHz 10 MHz Differential arm length: (gravitational wave signal) heterodyne detection Schnupp modulation Signal-Recycling control: separate modulation frequency reflected beam from beam splitter AR coating

Reaction Pendulum: 3 coil-magnet actuators at intermediate mass Electrostatic actuation on test mass bias 500V, range 0-800V=4µm Test Mass Actuators <10Hz >10Hz

Alignment Control differential wave-front sensing spot position control 4 degrees of freedom at MC 1 +4 at MC 2 +4 at MI (common mode) +2 at MI (differential mode) +2 at Signal-Recycling cavity = 36 Alignment Control

Magnet/coil actuators on IM UGF: ~10Hz Diff. MI Fast Auto-Alignment Output port  Reduces misalignment below 50 nrad rms  Reliable locking over long timescales. Duty cycle >95%

Output mode Radii Of Curvature of folding mirrors do not match East ROC: 687m North ROC: 666m Spec: 640m

Thermal adjustment of ROC + -

Thermal adjustment of ROC (II)

15 W 10 W

15 W 20 W

15 W 30 W

15 W 40 W

15 W 50 W

15 W 50 W

15 W 60 W

15 W 70 W

Signal Recycling Mirror Reflectivity = 99% Coil/magnet actuation directly to mirror Triple pendulum suspension with reaction pendulum chain Tunable between 550Hz and 5kHz Mode-healing 2x

Signal Recycling Mirror Reflectivity = 99% Coil/magnet actuation directly to mirror Triple pendulum suspension with reaction pendulum chain Tunable between 550Hz and 5kHz Mode-healing 5 kHz3 kHz 1 kHz

Sensitivity Development Dec Aug Nov Jan % 98.5% 95.2% 98.7%