GEO600

Harald LückHarald LückRuthe, 4.9.2003

Worldwide Interferometer Network

Laser

Optical Layout

Michelson Interferometer

Output Mode Cleaner

Mode Cleaners

600m 10 W 5 W

1 W

~ 5 kW

10 kW atBeam Splitter

~50mW

Light power (specs)

GEO 600 Sensitivity (specs.)

Tunable SensitivityS

trai

n se

nsiti

vity

[1/

sqrt

(Hz)

]

Frequency [Hz]

Therm. noise

TMSR = 0,1%

TMSR = 1%

TMSR = 5%

Laser

Light Power (current)

Michelson Interferometer

Output Mode Cleaner

Mode Cleaners

10W 1W

300W atBeam Splitter

2W

~10mWMode Cleaners:

Troughput 80% 72%

Finesse 2700 1900

Visibility 96% 92%

R=98.65%

Power Recycling Cavity:

Mode matching 97%Finesse 450Linewidth 270 Hz

Optical Layout

Main Interferometer

Mode Cleaner

Laser Bench

Output Bench

Slave

Master

Master

Slave

entrance to vacuum system

Laser SystemMaster Laser:

Nd:YAG NPRO (non-planar ring

oscillator) 800mW @ 1064 nm

Slave Laser:

Nd:YAG injection-locked ring

cavity 14 W @ 1064nm less than 5% in higher

modes

GEO Triple Pendulum Suspension

active

passive

STS2

D-space

Thermal Noise Issues Monolithic Suspension

Silicate (Hydroxy- Catalysis) Bonding

WeldGlas Fibres (coated)

Intermediate mass

Mirror

Frequency and Length Control

MichelsonInterferometer

Output Mode Cleaner

Laser

Mode Cleaners25 MHz13 MHz37 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

MichelsonInterferometer

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

16 + 20 = 36

Alignment Control

Fast AAFast

AA

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 runS1: 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 W10 W

15 W30 W

15 W51 W

15 W60 W

15 W60 W

15 W

71 W

15 W74 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 channels @ ~1Hz- ca . 60 GB/day

Data Acquisition

Data Acquisition System

LabView detector control

DAQ computer

raw data

GEO site Hannover

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++ monitorshigh mass inspiral

Berlin tape archive

Cardiff tape archive

Golm (180x2 nodes) cw analysis

burst analysis

Glasgow (24 nodes)

directed pulsar searchBayesian burst search

B‘ham(100x2 nodes) pulsar normal modes,

GW background,inspiral

Cardiff (64 nodes)

inspiral, periodicand bursts analysis

HDD capacity 100days

LAL

amplitude

phase accumulator

phase increment register

modulo 2

sine table

GPS time

Control computer

digitalPLL

sign

4 MHz

1 PPS

data acquisitionsystem

divider

GPS antenna

Multiplication

toIFO

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