GEO600 Harald Lück Ruthe,

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.)

Tunable Sensitivity Strain sensitivity [1/sqrt(Hz)] Frequency [Hz] Therm. noise T MSR = 0,1% T MSR = 1% T MSR = 5%

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% R=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

GEO Triple Pendulum Suspension active passive STS2 D-space

Thermal Noise Issues  Monolithic Suspension Silicate (Hydroxy- Catalysis) Bonding Weld Glas Fibres (coated) Intermediate mass Mirror

Frequency and Length 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 round trip arm difference ~10cm Signal-Recycling control: separate modulation frequency reflected beam from beam splitter AR coating UGF ~400Hz

Reaction Pendulum: 3 coil-magnet actuators at intermediate mass range ~100µm Test Mass Actuators <10Hz >10Hz Electrostatic actuation on test mass bias 500V, range 0-800V= 4µm

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 Fast AA

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 >98%

Detector control is done with analog electronics and supervised by a digital LabView system (~200 control loops, ~1000 channels) -Pre-alignment, Auto-alignment, Drift control -Lock acquisition -Operator interactions System Control

GEO sensitivity during S1 run S1: 17days, Aug02-Sep02, longest lock: 121h, duty cycle 98.5%

Fall 2002: Exchanged last test optics for final optics Final Optics Installation

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 30 W

15 W 51 W

15 W 60 W

15 W 60 W

15 W 71 W

15 W 74 W

Fall 2002: Implementation of Signal Recycling mirror Final Optics Installation

-VxWorks/Tornado based DAQ -24-bit ADC interface: 32 + (2*) 16 channels up to 16kSample/sec -12-bit ADC interface: 64 channels with 512 Sample/s -LabView system acquires ~ 1000 ~1Hz -ca. 60 GB/day Data Acquisition

Data Acquisition System LabView detector control DAQ computer raw data GEO siteHannover raw data detector status database frame data frame maker frame data tape writer data collecting units (DCUs) Radio Link Capacity: 3 days

Data Analysis Network frame data Hannover (13 nodes) burst analysis, DCR, GEO++ monitors high mass inspiral Berlin tape archive Cardiff tape archive Golm (180x2 nodes) cw analysis burst analysis Glasgow (24 nodes) directed pulsar search Bayesian burst search B‘ham(100x2 nodes) pulsar normal modes, GW background, inspiral Cardiff (64 nodes) inspiral, periodic and bursts analysis HDD capacity 100days

LAL amplitude phase accumulator phase increment register modulo 2  sine table GPS time Control computer digital PLL sign 4 MHz 1 PPS data acquisition system divider GPS antenna Multiplication to IFO 50 kHz optical isolation 1 PPS Microcontroller 50 kHz DDS (direct digital synthesiser) phase error of less than 1% (of a full cycle) on timescales of months, recoverable from interruptions Hardware injection of simulated cw signals

Tour Guides Dr. Morag Casey Labview Control Dr. Hartmut Grote Control, Aligment Uta Weiland Data related issues Dr. Michael Plissi Stefan Goßler Suspension Dr. Kasem Mossavi Vacuum