Transcript Amaldi 2001 - Max-Planck

The GEO 600 Detector
Andreas Freise
for the GEO 600 Team
Max-Planck-Institute for Gravitational Physics
University of Hannover
May 20, 2002
Network of Interferometric Detectors
GEO
LIGO
VIRGO
TAMA
ACIGA
May 20, 2002
Andreas Freise
gallery
the central building
clean in
room
central area
North Arm
600 m
East Arm
600 m
trench with
vacuum tube
GEO 600 - Optical Layout
Mode Cleaners
Michelson Interferometer
with Dual-Recycling
folded arms with an optical
path length of 2400 m
Laser
14 W
2 triangular ring
cavities (8 m optical
path length)
Output Mode Cleaner
triangular ring cavity
May 20, 2002
Andreas Freise
GEO 600 Sensitivity
narrowband
configuration
broadband configuration
May 20, 2002
Andreas Freise
Vacuum Enclosure
Mode Cleaners
Michelson
Interferometer
Laser
400 m3 volume / 4000 m2 surface
600 m long tubes, 60 cm diameter
2 m tall tanks with 1 m diameter
tubes :
110-8 mbar
main tanks : 510-8 mbar
Output Mode Cleaner
May 20, 2002
Andreas Freise
Seismic Isolation
The mechanical structure inside
each vacuum tank is mounted on
three Stacks:
rubber layer
geophon z
geophon x
bellow
geophon y
PZT
z
flange
Triple Pendulum Suspension
May 20, 2002
Andreas Freise
Monolithic Suspension
Weld
Silicate
(HydroxyCatalysis)
Bonding
May 20, 2002
Andreas Freise
Status May 2002 (I)
final optics
Mode Cleaners
Michelson Interferometer
test optics
Laser
Laser + Mode Cleaners complete
Power-Recycled Michelson with low finesse
Two main mirrors with monolythic suspension
May 20, 2002
Andreas Freise
Laser System
Master Laser:
entrance to
vacuum system
Nd:YAG
NPRO (non-planar ring
oscillator)
800mW @ 1064 nm
Slave
Slave Laser:
Nd:YAG
injection-locked
Master ring
cavity
14 W @ 1064nm
less than 5% in higher
modes
Slave
Master
May 20, 2002
Andreas Freise
Light Power
Michelson Interferometer
Mode Cleaners
Laser
10 kW at
Beam Splitter
~ 5 kW
10 W
5W
1W
Output Mode Cleaner
~ 4 mW (carrier)
+ ~ 100 mW (modulation sidebands)
May 20, 2002
Andreas Freise
Status May 2002 (II)
final optics
Michelson Interferometer
Mode Cleaners
test optics
Laser
200 W at
Beam Splitter
2W
1W
MPR
Mode Cleaners:
Troughput
80%
72%
Finesse
2700
1900
Visibility
96%
92%
~ 50 mW
May 20, 2002
Andreas Freise
Automated Control
control loops made of
analog electronics
supervised by digital electronics
controlled by distributed
virtual instruments (LabView)
May 20, 2002
Andreas Freise
Length and Frequency Control
Mode Cleaners
25 MHz
13 MHz
37 MHz
Laser
Laser Frequency
Stabilisation:
Michelson
Interferometer
no rigid reference cavity
laser is directly stabilised
to suspended cavities
3 sequential PoundDrever-Hall control loops
Measured in-loop stability at the
main interferometer input :
0.1 mHz/sqrt(Hz) @ 100 Hz
common mode of the
Power-Recycled
Michelson
Output Mode
Cleaner
serves as frequency
reference
May 20, 2002
Andreas Freise
Michelson Length Control
Mode Cleaners
Differential arm length:
(gravitational wave signal)
heterodyne detection
Laser
Schnupp
modulation
Michelson
Interferometer
15 MHz
10 MHz
Signal-Recycling control:
separate modulation
frequency
reflected beam from
beam splitter AR coating
Output Mode Cleaner
May 20, 2002
Andreas Freise
Test Mass Actuators
Reaction Pendulum:
3 coil-magnet actuators at
intermediate mass
Electrostatic actuation on test mass
May 20, 2002
Andreas Freise
Alignment Control (I)
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
differential wave-front sensing
Status May 2002:
spot position
control
Complete
(except
for SignalRecycling mirror)
May 20, 2002
Andreas Freise
Alignment Control (II)
Light on the main photo detector
May 20, 2002
Andreas Freise
Data Acquisition
Data acquisition uses 3 Data Collecting Units (DCUs)
with (in total) :
64 channels @ 16384 Hz
64 channels @ 512 Hz
~ 1000 channels @ 1Hz
Possible data rate:
600kB/sec
~ 50 GB/day
May 20, 2002
Andreas Freise
Coincidence Run with LIGO
100
90
Engineering run 28.12.2001 - 14.01.2002
Percentage of time in lock
80
70
60
50
40
30
20
430
of continuous
taking
Dailyhours
overall
duty cycles,data
maintenance
~ 0.9 TB
data recorded
periods
notofsubtracted
10
0
31.12.01
02.01.02
04.01.02
06.01.02
08.01.02
Date
10.01.02
12.01.02
May 20, 2002
14.01.02
Andreas Freise
Detector Improvement (I)
Detector characterisation groups analyse data from
coincidence run
Example: analysis of detector data for all times at
which the Michelson interferometer left its normal
operating point:
Checked wiring of the laser
electronics, found and
removed ground loops.
duration
36 lock
lossesof continuous
locking
of the mode cleaner
(on 10.01.2002)
section improved from
~4 hours to up to 100 hours
Cause of loss of lock
No
Manual alignment
2
Seismic event
2
Stack movement
2
Spot position event
2
Spike in laser channel
12
Acquisition failure
7
Not identified
9
May 20, 2002
Andreas Freise
Detector Improvement (II)
Experimental optimisation period:
electronics for Michelson servo loops are being completed
Michelson automatic alignment is completed
losses inside interferometer have been reduced
(PR gain improved from 15 to 200)
known problem with beam splitter suspension has been
fixed
sensitivity has been improved from 10-17 1/sqrt(Hz)
to 10-18 1/sqrt(Hz) @ ~ 300 Hz
May 20, 2002
Andreas Freise
Future steps
Optimisation (Michelson) June 02
Coincidence run with LIGO (S1) July 02
Implementation of Signal-Recycling end of July 02
Optimisation (Dual-Recycling) Aug.-Oct. 02
Installation of final subsystems starting Nov. 02
Coincidence run with LIGO (S2) end of Nov. 02
May 20, 2002
Andreas Freise