Status of GEO600

Status of GEO600

Benno Willkefor the GEO600 team

ESF Exploratory Workshop

Perugia, September 2005

ESF 05 / GEO, B. Willke


container cluster 2005

Workshop Central Building

Bathrooms

OfficesControl Room / Visitor Center


Tube / Trench


Clean Room / Control Room


Triple Pendulum Suspension


Thermal Noise / Monolithic Suspension

Silicate (Hydroxy- Catalysis) Bonding

Weld


reaction pendulum


12W Laser

modecleaner

interferometer with „dual recycling“

detektor

GEO 600 – optical layout


Dual Recycling Length Control


< 10 Hz

> 10 Hz

< 0.1Hz

Michelson length control

Reaction Pendulum:

3 coil-magnet actuators at intermediate mass, range ~ 100µm

Electrostatic actuation on test mass bias 630V, range 0-900V= 3.5µm


Alignment Control

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


GEO 600 design sensitivity


102

103

10-21

10-20

10-19

10-18

10-17

Frequency [Hz]

h(t

) [H

z-1/2

]

Jan 02

Aug 02 (S1)

Jan 04 (S3)

Sept 05

Feb 05 (S4)

Aug 04

Evolution of the GEO 600 Sensitivity


GEO600 Duty Cycle

date run name duty cycle

longest lock

Jan 2002 E7 75% 3h 40min

Aug 2002 S1 98% 121h

Nov 2003Jan 2004

S3-I (7days)S3-II(14 days)

95%98%

95h

Aug 2004 –Jan 2005

over night runs

(51 days)

94%

Mar 2005 S4 97% 52h


S4

Feb 22nd – March 23rd, 708 hours Two manned shifts/day (5-21 UTC), 1 „Expert-On-Duty“ 8-8UTC Fully automated overnight shifts; SMS alarms to ‚E-O-D‘

Locking status DAQS (DCUs running, frame making, timing, calibration) Temperatures Vacuum

Instrumental duty cycle 97.5%, 95% w/o noisy period, 72%>10h

Longest lock 52h


detector characterization

Sensitivity Min/max spectrum of

h(t) 15 BLRMS of h(t) Inspiral monitor Spectrogram of h(t)

Calibration Data quality Chi2 Calibration

parameters

Bursts (HACRmon) Time frequency

distribution SNR distribution Duration Bandwidth

Lines (Linemon) Line cataloguing Harmonic

identification Sideband

identification


Typical S4 Sensitivity


Calibration


On-line optical TF measurements

actuator optical

CAL P and Q

h


Calibration

radiation pressure

calibrator

?


Photon Pressure Calibrator

Good agreement with ESD calibrationWavelength: 1035 nm @ 20°CMax. power: 1.4 W, FWHM= 0.66nm


Optical Gain


Calibrated EP Quadrature Signals

h [1

/sqr

t(H

z)]


Combining hP(t) and hQ(t) – results

h [1/sqrt(Hz)]

Get the best of hP and hQ plus a little extra!

Get the best of hP and hQ plus a little extra!


Laser

Michelson Interferometer

Output Mode Cleaner

Mode Cleaners

10W 1.6W

1500W (typ.) 2000W (max) atBeam Splitter

5W

~40mW

T=0.09%

Power Recycling Cavity:

Mode matching >85%Finesse 8300Linewidth 30 Hz

4/0.09%*1.6 = 7000

increase of power recycling factor


Thermal lensing in BSoutput mode pattern (PRMI)

Directly after relocking

f=20km

A few minutes after relocking

f= 8km

→ α≈0.3 +/- 0.05ppm/cm


GEO 600 design sensitivity


Tuning signal recycling to 300 Hz

lock acquisition at 5kHz

tuning needs to adjust of 6 parameters (look-up table)

improved input file for simulations and how to transfer results to experiment

achieved downtuning to 200Hz

MI AA instability could be fixed


Interferometer Readout - Sidebands

phasemodualtor

laser beam splitter

mirror

mirror

photodetector


Schnupp – Modulation

phasemodualtor

laser beam splitter

mirror

mirror

photodetector


Gravitational Wave Side Bands

phasemodualtor

laser beam splitter

mirror

mirror

photodetector


Detuned Signal Recycling

phasemodualtor

laser beam splitter

mirror

mirror

photodetector


Unbalanced Sidebands

PRC

SRCbroad-band

SRCdetuned to1.1 kHz

MI-sidebandsSR-sidebands broadband

SR-sidebands1.1kHz detunedcarrier

-119 * fPRC

-72 * fPRC

72 * fPRC

119 * fPRC

0

72 D ( 765Hz) D (1.26kHz) D (1.26kHz) 72 D ( 765Hz)

2.2kHz 1.1kHz1.86kHz 2.3kHz

SR-sidebands2kHz detuned


Signal Recycling digital

digital loop allows for steep filter

noise contribution reduced by up to a factor of 200


Sqrt circuits in MI loop

ESD: F U^2

Sqrt circuits are necessary to give full linear force range for acquisition.

Drawback: sqrt circuits are noisy 1µV/sqrt(Hz)(=100µV/sqrt(Hz) @ ESD)


MI loop whitening / dewhitening

dewhiten

dewhiten

dewhiten

Whiten

Whitening right after mixer:zero 3.5 Hzpole 35 Hz

Dewhitening for both split passes

Passive dewhit-ening done in HV path (0-1kV)


sensitivity improvements since July


102

103

10-21

10-20

10-19

10-18

10-17

Frequency [Hz]

h(t

) [H

z-1/2

]

Jan 02

Aug 02 (S1)

Jan 04 (S3)

Sept 05

Feb 05 (S4)

Aug 04

Evolution of the GEO 600 Sensitivity


Current vs. Design sensitivity

102

103

10-24

10-23

10-22

10-21

10-20

10-19

10-18

10-17

Freq. [Hz]

ASD

[h/ H

z]GEO600 Theoretical Noise Budget

SeismicSuspension TNSubstrate TNCoating TNThermorefractiveShot 350HzTotalShot Sept 1 h(t) Sept 1


Non-stationary Noise


Near Future

finish commissioning increase circulating power find source of optical losses in PR cavity increase MI loop gain between 1-10 Hz improve RF circuitry optimize stability

join S5 in overnight/weekend mode until commissioning is finished

fully join S5


Documents

Status of GEO600