k ILIAS Meeting, Palma, Title GEO 600 Commissioning Status Based on a talk of Stefan Hild for the WG1 meeting in Perugia Max-Planck-Institut für Gravitationsphysik (Albert-Einstein-Institut) ück for the GEO600 Comissioning team ILIAS meeting Palma, O
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Harald Lückfor the GEO600 Comissioning team 1ILIAS Meeting, Palma, Oct. 2005 Title GEO 600 Commissioning Status Based on a talk of Stefan Hild for the.
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Harald Lück for the GEO600 Comissioning team 1 ILIAS Meeting, Palma, Oct. 2005
Title
GEO 600Commissioning Status
Based on a talk of Stefan Hild for the WG1 meeting in Perugia
Max-Planck-Institut für Gravitationsphysik(Albert-Einstein-Institut)
Harald Lück for the GEO600 Comissioning team ILIAS meeting Palma, Oct. 2005
Harald Lück for the GEO600 Comissioning team 2 ILIAS Meeting, Palma, Oct. 2005
GEO 600 layout
1.5-2 kW
0.09
Harald Lück for the GEO600 Comissioning team 3 ILIAS Meeting, Palma, Oct. 2005
Tuning signal recycling to 300 Hz
Better knowledge of IFO parameters:
more accurate parameter predictions from simulations
downtuning to 200 Hz realized
Fixed instability of MI auto-alignment by setting up a new telescope for DWS.
We will stay at 330 Hz !
Harald Lück for the GEO600 Comissioning team 4 ILIAS Meeting, Palma, Oct. 2005
GEO 600 design sensitivity
Harald Lück for the GEO600 Comissioning team 5 ILIAS Meeting, Palma, Oct. 2005
RF setup
OLD setup
New setup:
• Using a less noisy splitter(0/90°)
• Using a cable as phaseshifter
NEW setup
Old setup:
• Dominated by phase noise in the LO path (phaseshifter and splitter(0/90°)
• Due to this noise Q was mixed into P quadrature.
Harald Lück for the GEO600 Comissioning team 6 ILIAS Meeting, Palma, Oct. 2005
Shot noise
Green line is the shot noise level calculated from the DC current of the photodiode.
We are within a factor sqrt(2) shot noise limited above 1kHz !
Harald Lück for the GEO600 Comissioning team 7 ILIAS Meeting, Palma, Oct. 2005
Next step in RF setup (next week)
Proposed by Rana and others
GOALS: • Using only high quality hardware • Guaranteeing high RF levels in all components
Harald Lück for the GEO600 Comissioning team 8 ILIAS Meeting, Palma, Oct. 2005
Noise projections 21st of july
Harald Lück for the GEO600 Comissioning team 9 ILIAS Meeting, Palma, Oct. 2005
Noise in the SR-long loop
Noise in the detection band is entirely limited by front-end-noise (shot noise from the detector).Limits sensitivity from 100 to 500 Hz
PROBLEM
• Large locking range• OLG of 10^6 at 0.1 Hz• No feedback noise above100 Hz
Requirements
1. Servo has a locking mode and a running mode2. Lowering UGF to get less gain in detection band3. Using lowpass filter with very steep roll off above UGF
(implemeted digitally using a dSPACE system)
Solution
Harald Lück for the GEO600 Comissioning team 10 ILIAS Meeting, Palma, Oct. 2005
Analog SR electronics
Red = acq amp, green = acq phaDark blue = run amp, brown = run phaseLight blue = run2 amp, pink = run2 pha
Harald Lück for the GEO600 Comissioning team 11 ILIAS Meeting, Palma, Oct. 2005
Signal Recycling digital
Phase @18 Hz = -147 deg
Harald Lück for the GEO600 Comissioning team 12 ILIAS Meeting, Palma, Oct. 2005
SR feedback: analog vs. digital
Harald Lück for the GEO600 Comissioning team 13 ILIAS Meeting, Palma, Oct. 2005
Sensitivity improvement July to August
High frequency improvements: reduction of RF phase noiseLow frequency improvements: reduction of Signal recycling feedback noise
Harald Lück for the GEO600 Comissioning team 14 ILIAS Meeting, Palma, Oct. 2005
PR-bench
Historically grown layout of PR-bench not optimal !
• beam clipping• too many
transmissive optical components
• too many polarizing components
• acoustic coupling
Goal:Shorten and simplify the HPD path
Harald Lück for the GEO600 Comissioning team 15 ILIAS Meeting, Palma, Oct. 2005
Sensitivity after PR bench work
Removed resonance structures between 100 and 200 Hz.
Harald Lück for the GEO600 Comissioning team 16 ILIAS Meeting, Palma, Oct. 2005
Noise projections 4th of August
Harald Lück for the GEO600 Comissioning team 17 ILIAS Meeting, Palma, Oct. 2005
Michelson length control
< 0.1Hz
Harald Lück for the GEO600 Comissioning team 18 ILIAS Meeting, Palma, Oct. 2005
< 10 Hz
< 0.1Hz
Michelson length control
Reaction Pendulum:
3 coil-magnet actuators at intermediate mass, range ~ 100µm
Harald Lück for the GEO600 Comissioning team 19 ILIAS Meeting, Palma, Oct. 2005
< 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
Harald Lück for the GEO600 Comissioning team 20 ILIAS Meeting, Palma, Oct. 2005
Using ESD as actuator
• Force is proportional to square of applied voltage.
• high voltages are needed
• for bipolar actuation a bias voltage needs to be applied
Noise is introduced:
• loop electronics
• sqrt circuits
• intrinsic HV amplifier noise
Harald Lück for the GEO600 Comissioning team 21 ILIAS Meeting, Palma, Oct. 2005
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)
Harald Lück for the GEO600 Comissioning team 22 ILIAS Meeting, Palma, Oct. 2005
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)
Bypassing sqrt circuits after lock is acquired.
Sqrt circuits in MI loop
Harald Lück for the GEO600 Comissioning team 23 ILIAS Meeting, Palma, Oct. 2005
Noise in MI loop
HVA noise = 100nV/sqrt(Hz) (=10µV/sqrt(Hz) @ ESD)
HV-amplifier noise can be reduced by decreasing bias voltage or active noise suppression.
Suppressing noise introduced by loop electronics needs whitening
Harald Lück for the GEO600 Comissioning team 24 ILIAS Meeting, Palma, Oct. 2005
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)
Harald Lück for the GEO600 Comissioning team 25 ILIAS Meeting, Palma, Oct. 2005
Sensitivity after fixing noise from MI loop
Harald Lück for the GEO600 Comissioning team 26 ILIAS Meeting, Palma, Oct. 2005
Noise Projections 6th of October: Excess noise @ 200Hz
Harald Lück for the GEO600 Comissioning team 27 ILIAS Meeting, Palma, Oct. 2005