Recent Progress of TAMA300

Koji Arai(National Astronomical Observatory of Japan)
on behalf of the TAMA collaboration

K.Arai - TAMA ProjectTAMA300 interferometerl Laser interferometer GW detector- Arm length: 300m
- Location:
National Astronomical Observatoryof Japan (Mitaka, Tokyo)

l Purposes- Development of the detector
capable to catch GW eventsin nearby galaxies- Establishment of interferometer
technologies for LCGTK.Arai - TAMA ProjectProgress of TAMA300
1995-1997

Facility/Vacuum System Construction

Recombined Interferometer
1999-2001
6 times of observation runs
(Total 1370 hours)
Recycled Interferometer2001
Implement of power recycling
2003-2004
3 times of observation runs
(Total 1740 hours)
Seismic Attenuation System (SAS)2005
Start installation of SAS
2007
Full interferometer lock with SAS
K.Arai - TAMA ProjectCurrent focus

l Establishment of detector operation with SAS
Replacement of the vibration isolation system
pneumatic
active isolator+ stack+ double pendulum

inverted pendulum+ vertical filters+ multiple pendulum

To realize the improvement- Optimization of SAS control- Optimization of interferometer control- Application of digital control system=>Enables the complex servo system=>High level automatization of the operation

K.Arai - TAMA ProjectInterferometer
configuration
300m
Fabry-Perot
Cavity10-Winj.-locked
Nd:YAG
10-m
laser
ModeCleaner

OpticalLevers

Recycled
Fabry-Perot
Michelson
interferometer

Wave Front
Sensors
Lengthsensors

SASfor test masses
K.Arai - TAMA Project

Seismic Attenuation Systeml Structure of SAS
Multiple pendulum suspended from IP
IP top

MGAS filter(Monolithic
Geometric Anti-Spring)

invertedpendulum(IP)platform
double pendulumwith recoil mass

K.Arai - TAMA Project

Seismic Attenuation Systeml Vibration Isolation
Passive isolation with soft springs + active damping
Tortional

Vertical

f~40mHzf~500mHz

Tortion Pendulum
Inverted Pendulum
f~500mHz

Horizontal

MGAS Filter
MiniGAS Filter
f~1.5Hz

Inverted Pendulum
f~30mHzMultiple Pendulum
f~650mHz

K.Arai - TAMA Project

Seismic Attenuation System

l Active Control of SAS

Local control stabilize the mirror motion=> to enable lock of the interferometer

Local control
IP Position

Sensor: LVDT
Bandwidth: ~60mHz

IP Inertial damping
Sensor: Accelerometer
Bandwidth: 60m~2Hz

Global control
IP Position

Bandwidth: ~10mHz

Plat form

Bandwidth: ~10mHz

Test mass (angular)
Bandwidth: <3Hz

Tortion damping

Sensor: Photo Sensor
Bandwidth: 40mHz

Test mass (Length)
Bandwidth: <1kHz

Test mass servo

Sensor: Optical Lever
Bandwidth: ~2Hz

K.Arai - TAMA ProjectInertial damping of IP

l Diagonalization of Sensors / Actuators

Decompose Actuator -> Sensor response
into mechanical eigenmodes of IP=> servo design becomes simpler
allows the different strategy for each modes
LVDT

10

Transfer Function

Actuator

Act -> Sensor Response

1010-110-210-310

beforediagonalization-2IP LegAccelerometer

IP Top Table(Filter Zero)

Transfer Function

1023

4 5 6 7-1

210

3Frequency [Hz]4 5 6 70210010-1

10-2

10after-4 diagonalization
-3

10
10

K.Arai - TAMA ProjectInertial damping of IP

K.Arai - TAMA Projectl Two loop configuration

LVDT loop (position sensing loop)
f<60mHz- drift control of the IP position
Accelerometer loop (inertial sensing loop)
60mHz<f<2Hz- stabilization of IP in terms of the inertial frame- damping of the pendulum reactions at around 1Hz

Openloop Gain

101
100
10-110-2 LVDT
10-3
10-2

ACC

10-1100

101

Frequency[Hz]Test mass control

K.Arai - TAMA Projectl Optical lever servo

Rather complicated servo loops have been realized
in virtue of digital control
Openloop Gain

104100

Pitch

Unity Gain
Frequency
~3Hz

10-2
10-4
10-6
10-8

Phase [deg]

Yaw

102

10-2

10-1102103

18012060
0-60-120-180
10-2100
101
Frequency [Hz]

10-1

100

102

103

101

K.Arai - TAMA Project

Performance of SASl Test mass angular motion

Angular Fluctuation [rad/rtHz] or RMS [rad]Mirror angular motion: sub-µradRMS=> Sufficiently stable for interferometer operation(with previous suspension system: 1.0 µradRMS)
10-4

Free Run: 1.4 µradRMS
Pitch Controlled: 0.23 µrad
RMS

10-4

10-5

10-5

10-6

10-6

10-7

10-7

10-8

10-8

10-9

10-9

10-10 -2
1010-1100
Frequency [Hz]

101

102

Free Run: 12 µradRMS
Yaw Controlled: 0.16 µrad
RMS

10-10 -2
1010-1

100

101

Frequency [Hz]102

K.Arai - TAMA Project

Performance of SASl Legth Fluctuation of 300-m arm

Comparison with the previous suspension system=> improvement above 0.1Hz was confirmed
Displacement noise [m/rtHz] or RMS [m]10-5

Old Suspension
1.4µmRMS@f>50mHz

10-6
10-710-8

With SAS
0.84µmRMS@f>50mHz

10-910-10
10-1110-2

10-1

Frequency [Hz]100101Interferometer
configuration
300m
Fabry-Perot
Cavity10-Winj.-locked
Nd:YAG
10-m
laser
Mode
Cleaner

OpticalLeversRecycled
Fabry-Perot
Michelson
interferometer

Wave Front
Sensors
Lengthsensors

SASfor test masses
K.Arai - TAMA ProjectInterferometer Operationl Recycling operation with SAS was achieved in Julyl Control configuration
Test mass length control:
Analog based servo

DSP based digital filter=> only for lock acquisition=> switched to analog based system after the lock

Test mass alignment control:
LabView based digital control
Optical lever control

for fast control

Wave Front Sensing

for drift control
K.Arai - TAMA ProjectDigital mass lock filterl DSP based digital filter (TI TMS32C6713 225MHz)
Sampling freq:

200kHzControl BW:~800HzRealized comperable bandwidth to analog filters

K.Arai - TAMA ProjectDigital mass lock filterl Some simple operations to the error signal- Trigger at the resonance
Eliminates glitches by sidebands/ higher order modes- Normalizaton of the error signal by cavity transmitted light
Expands linear range (about x3)- Adaptive change of the digital filter coefficient
Low frequency gain boost at the lock=> In combination with SAS, lock of RFPMI wasrealized even with 3 times weaker actuator

K.Arai - TAMA ProjectPre-emphasis / De-emphasisl One of the demerits of the digital system
about 100-1000 times larger noise than analog circuitsl Pre-emphasis/De-emphasis filter

pre-emphasis ADCDigitalSystemDAC

de-emphasis

Signal level is enhanced
while the range at low frequency is preserved
pre-emphasis:de-emphasis:

effect of ADC noise is reduced
effect of DAC noise is reduced

K.Arai - TAMA ProjectPre-emphasis /De-emphasis
AnalogOpticalLeverPE:
Z 3Hz-P 300Hz

Digital

Anti-PE:
P 3Hz-Z 300Hz

Servo Filter
Target UGF 2-3Hz

DE:
P 3Hz-Z 300Hz

Anti-DE:Z 3Hz-P 300Hz

α
ADC

Analog

DAC

Gain
Fader

1−α
Wave
Front
SensorLabView (fs=1kHz)PE:
Z 3Hz-P 300Hz

PoundDrever
HallSignal

Servo Filter
Target UGF 800Hz

DSP (fs=200kHz)

MatrixCircuit

Coil
Driver

K.Arai - TAMA Project

Sensitivityl Tuning of the system still underway
So far, improvement below 150Hz was confirmed
Displacement noise [m/rtHz]

10-10

TAMA300 Displacement Sensitivity(2007/08/31)

10-11
10-12
10-13
10-14

Best with SAS

10-15
10-16
10-17
10-18
10-19
101

Previous
best
102

103
Frequency [Hz]104
K.Arai - TAMA Project

Sensitivityl Tuning of the system still underway
So far, improvement below 150Hz was confirmed
Displacement noise [m/rtHz]

10-10

TAMA300 Displacement Sensitivity(2007/08/31)

10-11
10-12
10-13
10-14

Dark port light poweris still attenuated

10-15
10-16
10-1710-18
10-19101

Alignment
control noise(DA noise)
102

103
Frequency [Hz]104
K.Arai - TAMA ProjectPlanl How to achieve further improvement
For alignment noise

Additional DA noise reduction is in progress
Activation of fast WFS servo (~x100 better sensing noise)

For high frequency

more power at the dark port

For further investigationnoise budgetting => needs more stability

For further improvement of SAS

performance of SAS is limted by the accelerometers=> accelerometer study

K.Arai - TAMA ProjectSummaryl Current status- SAS is now functioning- Shaking down of the detector system
Underway. Still a lot of things to do.
- Improvement was partially confirmed
Between 0.1 to 150Hz- Gradually getting familiar with digital systemsl Plan- Improved binary range-> participation to AstroWatch campaign

K.Arai - TAMA Project