Transcript Amaldi 2001

The GEO 600 Detector
Andreas Freise
and the GEO 600 Team
University of Hannover
May 20, 2002
Location of GEO 600
GEO
LIGO
VIRGO
TAMA
ACIGA
May 20, 2002
Andreas Freise
thethe
gallery
the central building
clean in
room
the central area
North Arm
600 m
East Arm
600 m
the 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
triangular 8 m ring
cavities
Output Mode Cleaner
triangular 0.1 m
ring cavity
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 1m 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
vacuum tanks 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:
enter
vacuum system
Nd:YAG
NPRO (non-planar ring
oscillator)
800mW @ 1064 nm
Slave
Slave Laser:
Nd:YAG
Master ring
injection locked
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
~ 50 mW
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
Power-Recycled
Mode Cleaners: Michelson:
M
T=1.5%
Troughput
80%
PR
72%
Gain
Finesse
200
2700
1900
Contrast
Visibility 4000
91%
92%
~ 50 mW
May 20, 2002
Andreas Freise
Automated Control
Three types of control tasks:
controlled by distributed LabView
virtualdamping
instruments
1) Local control:
of pendulum
(digital bus,
readseismic
~1000 isolation,
control
resonances,
active
channels,
lock automation)
temperature
control
2) Global control of longitudinal degrees
digital
electronic
ofsupervised
freedom of by
optical
systems:
length
potentiometers,
and(digital
frequency
stabilisation CMOS
switches, mico-controller, AD
3) Global controlconverter)
of alignment of optical
components: Automatic alignment
system
control loops made of analog electronics
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
thethe
the
now
length
laser
pre-stabilised
frequency
of the firstlaser
ismode
locked
frequency
cleaner
to the
is locked
islength
locked
to
ofto
the
thethe
common
first
length
mode
of
mode
cleaner
the of
second
the
power-recycled Michelson interferometer
common mode of the
power-recycled
Michelson
Output Mode
Cleaner
serves as frequency
reference
May 20, 2002
Andreas Freise
Frequency Noise
Required frequency stability at the input of
the final interferometer: 10 Hz/sqrt(Hz)
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:
a separate modulation
frequency
reflected beam from 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)
DC: beam positions are defined by reference marks,
spot position control, below 0.1 Hz
around the resonance frequencies of the suspension pendulums
the beam follows the input beam from the laser bench,
differential wave-front sensing, 0.1 Hz to 10 Hz
no active control at the expected signal frequencies, the two
mode cleaners suppress geometry fluctuations by ~106
May 20, 2002
Andreas Freise
Alignment Control (II)
4 degrees of freedom
for MC 1
+4 for MC 2
+4 for MI common mode
+2 for MI differential mode
+2 for signal recycling
16
+ 32 = 48
Status May 2002:
Complete (except for the not yet
differential
installed
signalwave-front
recyclingsensing
mirror)
spot position control
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
Data Storage and Transfer
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
•
430 hours of continous data taking
•
Duty cycle (> 10mins) ~ 75%
•
98% for the last 24h.
•
Longest lock: 3h:38min
•
~ 0.9 TB of data recorded
60
50
40
30
20
Daily overall duty cycles, maintenance
periods not subtracted
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
Strain Sensitivity
May 20, 2002
Andreas Freise
Automated Control
Laser-mode-cleaner system with longitudinal control
and auto alignment runs continuously since December
2000
Total time for relocking the injection locked laser and
the two mode cleaners is typically < 40 sec
Continuous lock of the auto-aligned mode cleaner
system: 48 hours
Locked 1200 m cavity without any re-alignment
of the cavity mirrors for 36 hours
Continuous lock of the entire system: 10 hours
May 20, 2002
Andreas Freise