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Sora
HEPL Seminar
Feb. 11, 2009 @ Stanford Univ.
Seiji Kawamura
(National Astronomical Observatory of Japan)
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Outline
Gravitational waveDECIGODECIGO pathfinderSummaryAppendix
– Displacement noise free interferometer– Juggling interferometer
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Distortion of space ~ 10-23
Not yet detected!
• Predicted by Einstein• Emitted from accelerating objects• Propagates as tidal distortion of space
Gravitational wave
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GW Sources
• Neutron star / black hole binaries
• Supernova
• Beginning of the universe
• Etc.
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380,000 year(Transparent to
radiation)
EM1 sec(Formation of
Proton, Neutron)
Neutrino
How far (old) can we see?
Beginning ofthe universe
13.7 billion year(Now)
GW
10 -43 sec(Planck time)
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Gravitational wave astronomy
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Detection of GWby laser interferometer
Laser
Interfering beam
Beam splitter
Suspended Mirror Suspended Mirror
Detector
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The longer arm length gives larger signals!
Laser
Photodetector
Mirror
Mirror
Laser
Photodetector
Mirror
Mirror
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Large-scale detectors
LIGO (4 km)
LIGO (4 km)
VIRGO (3 km)
GEO (600 m)
TAMA (300 m)
CLIO (100 m)
LCGT (3 km)
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Recycling mirror:
Increase effective
laser power
Standard optical configuration
Fabry-P
ero
t arm
cavity
Fabry-Perot arm
cavity
Enhance GW signals
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Laser Interferometer in Space
• Signal increased - Due to longer interaction between GW and light - Cancellation of signals at higher frequencies
• Noise reduced - Lower seismic noise and gravity gradient noise
Sensitivity improvedat lower frequencies
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LISA• Arm length: 5,000,000km• Frequency range: 1 mHz - 0.1 Hz• Target Source: White dwarf binary, Giant BH coalescen
ce• Optical configuration: Light transponder
LISA project
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What is DECIGO?Deci-hertz Interferometer Gravitational Wave Observatory
(Kawamura, et al., CQG 23 (2006) S125-S131) Bridges the gap between LISA and terrestrial detectors Low confusion noise -> Extremely high sensitivity
10-18
10-24
10-22
10-20
10-4 10410210010-2
Frequency [Hz]
Str
ain
[H
z-1/2]
LISA
DECIGO
Terrestrial detectors (e.g. LCGT)
Confusion Noise
moved above
LISA band To be moved
into TD band
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Pre-conceptual designDifferential FP interferometer
Arm length: 1000 kmMirror diameter: 1 mLaser wavelength: 0.532 mFinesse: 10Laser power: 10 WMirror mass: 100 kgS/C: drag free3 interferometers
Laser
Photo-detector
Arm cavity
Drag-free S/C
Arm cavity
Mirror
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Why FP cavity?
Frequency
Str
ain
Radiation pressure
noise f -2
Shot noiseShot n
oise
f1Transponder type(e.g. LISA)
Shot noise
Shortenarm length
Shot nois
e f1
Radiation pressure
noise f -2
Transponder type(e.g. LISA) Shorten
arm length Implement FP cavity
Implement FP cavity
FP cavity type Better best- sensitivity
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Drag free and FP cavity: compatible?
Mirror
S/C IS/C II
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FP cavity and drag free : compatible?
Local sensor
ThrusterThruster
Mirror
Relative position between mirror
and S/C
S/C II S/C I
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Drag free and FP cavity: compatible?
Local sensor
ThrusterThruster
Mirror
Relative position between mirror
and S/C
Actuator
Interferometer output (GW signal)
S/C II S/C I
No signalmixture
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Orbit and constellation (preliminary)
Sun
Earth
Record disk
Increase angular resolution
Correlation for stochastic background
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Science by DECIGO (1)
Formation of Super-
massive BH
Frequency [Hz]
Str
ain
[H
z-1/ 2]
10-3 10-2 10-1 1 10 102 103
10-19
10-20
10-21
10-22
10-23
10-24
10-25
10-26
(1000 M◎ z=1)
BH binary
Coalescence
Radiation pressure noise
Shot noise
1 cluster
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Science by DECIGO (2)
Frequency [Hz]
Str
ain
[H
z-1/ 2]
10-3 10-2 10-1 1 10 102 103
10-19
10-20
10-21
10-22
10-23
10-24
10-25
10-26
5 years
NS binary (z=1)
Coalescence
3 months
Acceleration of Universe
⇓Dark energy
Radiation pressure noise
Shot noise
1 cluster
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Acceleration of Expansion of the Universe
NS-NS (z~ 1)GW
DECIGO
Output
Expansion + Acceleration?
Time
Str
ain
Template (No Acceleration)
Real Signal ?Phase Delay~ 1sec (10 years)
Seto, Kawamura, Nakamura, PRL 87, 221103 (2001)
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Science by DECIGO (3)
Inflation(GW=210-16)Verification
of inflation
Frequency [Hz]
Correlation(3 years)
Str
ain
[H
z-1/ 2]
10-3 10-2 10-1 1 10 102 103
10-19
10-20
10-21
10-22
10-23
10-24
10-25
10-26
Radiation pressure noise
Shot noise
1 cluster
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Requirements Acceleration noise should be suppressed below
radiation pressure noise– Force noise: DECIGO = LISA/50
(Acceleration noise in terms of h: 1, Distance: 1/5000, Mass: 100)
– Fluctuation of magnetic field, electric field, gravitational field, temperature, pressure, etc.
Sensor noise should be suppressed below shot noise.– Phase noise: DECIGO = LCGT×10
(Sensor noise in terms of h: 1, storage time: 10)– Frequency noise, intensity noise, beam jitter, etc.
Thruster system should satisfy range, noise, bandwidth, and durability.
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Roadmap200
708 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
Missio
nO
bjectives
Test of key technologiesObservation run of GW
Detection of GW w/ minimum spec.Test FP cavity between S/C
Full GW astronomy
Sco
pe
1 S/C1 arm
3 S/C1 interferometer
3 S/C,3 interferometer3 or 4 units
DICIGO Pathfinder(DPF)
Pre-DECIGODECIGO
R&DFabrication
R&DFabrication
R&DFabrication
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DECIGO Pathfinder (DPF)
Laser
PD
Floating Mirrors
Drag-free S/C
DECIGO DPF
30 cm
1,000 km
Shrink the arm lengthfrom 1,000 km to 30 cm
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Conceptual design and Technologies to demonstrate
Thruster
Local Sensor
Floating mirrorStabilization
system
Laser
Actuator
Drag-free control system Laser source and stabilization system Control of Fabry-Perot interferometer Launch-lock system
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Goal sensitivity of DPF
10–2 10–1 100 101 10210–18
10–17
10–16
10–15
10–14
10–13
10–12
10–11
10–19
10–18
10–17
10–16
10–15
10–14
10–13
10–12
No
ise
lev
el
[1
/Hz1/
2 ]
Frequency [Hz]
Shot noise
Mirror thermal
Laser Radiation
Laser: 1064nm, 25mWFinesse: 100Mirror mass: 1kgQ–value of a mirror: 10 6
Cavity length: 10cm
pressure noise
Thruster noise
PM acceleration Noise
Geogravity
Laser Frequencynoise
Dis
pla
ce
me
nt
No
ise
[m
/Hz1/
2 ]
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Expected sources
103 104 105 10610–1
100
101
102
Ob
serv
able
Ran
ge
Mass [Msolar]
[kp
c, S
NR
=5
]
Galactic Center
BH QNM
BH Inspiral
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JAXA’s Small science satellite series
• Plan to launch 3 small satellites between 2011 and 2015– using next-generation solid rocket booster
• Reduce time and cost by means of ‘Standard bus system’ – Bus weight : ~ 200kg, Bus power : ~ 800W– Downlink ~ 2Mbps, Data storage ~ 1GByte– 3-axes attitude control– SpaceWire-based data processing system
• We submitted a proposal for DPF
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In June 2007, I attended the LIGO PAC meeting at Caltech, and we were invited to dinner at a Chinese restaurant.
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We gainedmomentum!
DPF was selected as one of the 4 important mission candidates for small science satellite series run by JAXA/ISAS.
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DPF S/C
Size : 900mm cubeWeight : 200kgSAP : 800W Battery: 50AHDownlink : 2MpbsDR: 1GByte3N Thrusters x 4
Stabilized Laser
Interferometer Module
Thruster Control Unit
Solar Paddle
Interfererometer Control Unit
Housing Control Unit
Mission Thrusters
Central Processing Unit
Bus Thrusters
Satellite Bus (‘Standard bus’ system)
DPF PayloadSize : 900mm cubeWeight : 100kgPower : 200WData Rate: 600kbpsMission thruster x16
Power SupplySpW Comm.
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DPF Mission Outline
Orbit: Low-Earth (Altitude 500km), Sun-synchronous orbit (dusk-dawn)
Launcher: Single launch by M-V follow-on (solid rocket booster under development) PBS (Post-Boost stage) for fine orbit insertion
Launch: 2012 (target)Mission Lifetime: 1 year (nominal)
500km
DP
F
Attitude Control: Gravity-gradient stab. Drag-free control with mission thrusters (Safe hold control by bus thrusters)
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History and Future
2006 Nov. Submitted a proposal of DPF2007 Jun. Fortune cookie2007 Aug. Selected as a Pre-Phase-A mission R&D costs funded2008 Sep. Submitted Phase-A proposal2008 Dec. Hearing held for selecting the 2nd mission2009 Mar. 2nd mission will be selected
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Pre-DECIGOPre-DECIGO
DECIGO
Arm length 100 km 1000 km
Mirror diameter 30 cm 1 m
Laser wavelength 0.532 m 0.532 m
Finesse 30 10
Laser power 1 W 10 W
Mirror mass 30 kg 100 kg
# of interferometers in each cluster
1 3
# of clusters 1 4
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Sensitivity of Pre-DECIGO
10-24
10-23
10-22
10-21
10-20
10-19
10-18
10-17
10-16
10-15
Str
ain
sen
siti
vit
y [
1/r
Hz]
10-3
10-2
10-1
100
101
102
103
Frequency [Hz]
DPFDPFDPFDPF
NS-NS inspiral (@300Mpc)
pre-DECIGO
DECIGO
S/N~14 for NS-NS@300Mpc, 10-20 events/year
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Interim organizationPI: Kawamura (NAOJ)Deputy: Ando (Kyoto)
Executive CommitteeKawamura (NAOJ), Ando (Kyoto), Seto (NAOJ), Nakamura (Kyoto), Tsubono (Tokyo), Tanaka (Kyoto), Funaki (ISAS), Numata (Maryland), Sato (H
osei), Kanda (Osaka city), Takashima (ISAS), Ioka (Kyoto)
Pre-DECIGO
Sato (Hosei)
Satellite
Funaki (ISAS)
Science, Data
Tanaka (Kyoto)Seto (NAOJ)
Kanda (Osaka city)
DECIGO pathfinderLeader: Ando (Kyoto)
Deputy: Takashima (ISAS)
Detector
Ando (Kyoto)
Housing
Sato (Hosei)
Laser
Ueda (ILS)Musya (IL
S)
Drag free
Moriwaki (Tokyo)
Sakai (ISAS)
Thruster
Funaki (ISAS)
Bus
Takashima (ISAS)
Data
Kanda (Osaka
city)
Detector
Numata (Maryland)
Ando (Tokyo)
Mission phase
Design phase
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DECIGO-WGSeiji Kawamura, Masaki Ando, Takashi Nakamura, Kimio Tsubono, Naoki Seto, Shuichi Sato, Kenji Numata, Nobuyuki Kanda, Ikkoh Funaki, Takeshi Takashima, Takahiro Tanaka, Kunihito Ioka, Kazuhiro Agatsuma, Koh-suke Aoyanagi, Koji Arai, Akito Araya, Hideki Asada, Yoichi Aso, Takeshi Chiba, Toshikazu Ebisuzaki, Yumiko Ejiri, Motohiro Enoki, Yoshiharu Eriguchi, Masa-Katsu Fujimoto, Ryuichi Fujita, Mitsuhiro Fukushima, Toshifumi Futamase, Katsuhiko Ganzu, Tomohiro Harada, Tatsuaki Hashimoto, Kazuhiro Hayama, Wataru Hikida, Yoshiaki Himemoto, Hisashi Hirabayashi, Takashi Hiramatsu, Feng-Lei Hong, Hideyuki Horisawa, Mizuhiko Hosokawa, Kiyotomo Ichiki, Takeshi Ikegami, Kaiki T. Inoue, Koji Ishidoshiro, Hideki Ishihara, Takehiko Ishikawa, Hideharu Ishizaki, Hiroyuki Ito, Yousuke Itoh, Nobuki Kawashima, Fumiko Kawazoe, Naoko Kishimoto, Kenta Kiuchi, Shiho Kobayashi, Kazunori Kohri, Hiroyuki Koizumi, Yasufumi Kojima, Keiko Kokeyama, Wataru Kokuyama, Kei Kotake, Yoshihide Kozai, Hideaki Kudoh, Hiroo Kunimori, Hitoshi Kuninaka, Kazuaki Kuroda, Kei-ichi Maeda, Hideo Matsuhara, Yasushi Mino, Osamu Miyakawa, Shinji Miyoki, Mutsuko Y. Morimoto, Tomoko Morioka, Toshiyuki Morisawa, Shigenori Moriwaki, Shinji Mukohyama, Mitsuru Musha, Shigeo Nagano, Isao Naito, Kouji Nakamura, Hiroyuki Nakano, Kenichi Nakao, Shinichi Nakasuka, Yoshinori Nakayama, Kazuhiro Nakazawa, Erina Nishida, Kazutaka Nishiyama, Atsushi Nishizawa, Yoshito Niwa, Yoshiyuki Obuchi, Masatake Ohashi, Naoko Ohishi, Masashi Ohkawa, Norio Okada, Kouji Onozato, Kenichi Oohara, Norichika Sago, Motoyuki Saijo, Masaaki Sakagami, Shin-ichiro Sakai, Shihori Sakata, Misao Sasaki, Takashi Sato, Masaru Shibata, Hisaaki Shinkai, Kentaro Somiya, Hajime Sotani, Naoshi Sugiyama, Yudai Suwa, Rieko Suzuki, Hideyuki Tagoshi, Fuminobu Takahashi, Kakeru Takahashi, Keitaro Takahashi, Ryutaro Takahashi, Ryuichi Takahashi, Tadayuki Takahashi, Hirotaka Takahashi, Takamori Akiteru, Tadashi Takano, Keisuke Taniguchi, Atsushi Taruya, Hiroyuki Tashiro, Mitsuru Tokuda, Yasuo Torii, Morio Toyoshima, Shinji Tsujikawa, Yoshiki Tsunesada, Akitoshi Ueda, Ken-ichi Ueda, Masayoshi Utashima, Yaka Wakabayashi, Hiroshi Yamakawa, Kazuhiro Yamamoto, Toshitaka Yamazaki, Jun'ichi Yokoyama, Chul-Moon Yoo, Shijun Yoshida, Taizoh Yoshino
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1st InternationalLISA-DECIGO Workshop
• Nov. 12-13, 2008 @ ISAS, Sagamihara, Japan• Participants:
– Danzmann, Heinzel, Gianolio, Jennrich, Lobo, McNamara, Mueller, Prince, Stebbins, Sun, Vitale, …
• Accomplishments:– Mutual understanding
– Kick-off of collaborations
– Exposure of the missions to people in the neighboring fields
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Collaboration with Stanford
• UV LED discharge for DPF
• Other R&D for DECIGO
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Summary
• DECIGO can detect GWs from the inflation as well as can bring us extremely interesting science.
• DPF has been selected as one of the important mission candidates for small science satellite series; they plan to launch 3 missions in 5 years starting from 2011.
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Let DPF fly!
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Possible breakthrough for3rd-generation detectors:
Displacement-noise free Interferometer
Kawamura and Chen, PRL, 93, (2004) 211103Chen and Kawamura, PRL, 96 (2006) 231102
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Motivation Displacement noise: seismic Noise, thermal noise,
radiation pressure noise Cancel displacement noise shot noise limited
sensitivity Increase laser power sensitivity improved indefinitely
Frequency
Sen
siti
vity
Displacement noise
Shot noise
Laser
PD
Diplacement noise
Cancel displacement noise
Increase laser power
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GW and mirror motion interact with light differently
Difference outstanding forGW wavelength distance between masses
Mirror motionMirror motion
GW On propagation
On reflection
Light
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Cancel motion of objects
CBBCABBA
Motion of A, B, and C cancelled
GW signal remains
Clock
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Why is it possible?
# of MQ (4) > # of DOF (3)
MQ: Measurable quantityDOF: Degree of freedom
Therefore a combination of MQs that is free from DOFs exists!
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Clock noise?
CBBCABBA
Motion: cancelled
Clock noise:
not cancelled
Clock
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Why?
# of DOF (Clock): 3 # of DOF (Displacement): 3 # of MQ: 4
Therefore it is not always possible to make a combination of MQs that is free from all the DOFs!
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How can we cope with it?d: # of dimensions, N: # of Objects
# of DOF (Displacement) : Nd# of DOF (Clock) : N# of DOF (Total) : N(d+1)# of MQ : N(N-1)
If N(N-1)>N(d+1) i.e. N>d+2A combination of MQs that is free from D
OFs exists!
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Displacement-noise free interferometer
• Propagation time measurement interferometer
• Motion of object displacement noise of mirrors
• Clock noise laser frequency noise
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Example of DFI
Two 3-d bi-directional MZ
Take combination of 4 outputs
Mirror motion completely cancelled
GW signal remains (f 2)
![Page 54: Sora HEPL Seminar Feb. 11, 2009 @ Stanford Univ. Seiji Kawamura (National Astronomical Observatory of Japan)](https://reader035.vdocuments.us/reader035/viewer/2022070407/56649e385503460f94b29435/html5/thumbnails/54.jpg)
Experiment (Ideal)One bi-directional MZ
GWMirror motion Laser
PD
GW Mirror motion
Extract
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Experiment (Practical)
EOM used for GW and mirror motion
GWMirror motionLaser
PD
Laser
PD
~ ~Simulated mirror motion Simulated GW
Ideal Practical
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Results
Mirror motion GW signal
Mirror motion cancels outGW signal remains
Mirror motion to output
Difference
DifferenceGW signal to output
Sato, Kokeyama, Ward, Kawamura, Chen, Pai, Somiya, PRL 98 (2007) 141101
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Possible breakthrough for3rd-generation detectors:
Juggling Interferometer
![Page 58: Sora HEPL Seminar Feb. 11, 2009 @ Stanford Univ. Seiji Kawamura (National Astronomical Observatory of Japan)](https://reader035.vdocuments.us/reader035/viewer/2022070407/56649e385503460f94b29435/html5/thumbnails/58.jpg)
Motivation
10-8
10-9
10-10
10-11
10-12
10-13
10-14
10-15
10-16
10-17
10-18
10-19
10-201 10 100 Frequency [Hz]
Displacement [mHz-1/2]Seismic noise
Pendulum thermal noise
Radiation pressure noise
Shot noise
Limiting the low-frequency sensitivity
• Lower frequency gives higher GW signals.
• Suspension thermal noise and seismic noise are huge at low frequencies.
• What if we can remove suspension?
• Magnetic levitation is a kind of suspension.
• Free-fall experiment is just one shot.
![Page 59: Sora HEPL Seminar Feb. 11, 2009 @ Stanford Univ. Seiji Kawamura (National Astronomical Observatory of Japan)](https://reader035.vdocuments.us/reader035/viewer/2022070407/56649e385503460f94b29435/html5/thumbnails/59.jpg)
km-class juggling interferometer
3 km
Laser
Fiber
Laser beam
Beamsplitter
Clamp
Mirror
Clamp
![Page 60: Sora HEPL Seminar Feb. 11, 2009 @ Stanford Univ. Seiji Kawamura (National Astronomical Observatory of Japan)](https://reader035.vdocuments.us/reader035/viewer/2022070407/56649e385503460f94b29435/html5/thumbnails/60.jpg)
Simple Interferometer
Simple Michelson interferometer– FP cavity is not necessary because
the sensitivity is limited by displacement noise at low frequencies anyway
No fringe lock– Fringe lock is not necessary because
intensity noise can be suppressed and no power recycling is necessary
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Data processing 1
Produce displacement signal (x) from the two PD outputs
Dis
pla
cem
ent
Time
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Noise caused by juggling
• x:– Longitudinal position on release fluctuates
• dx/dt:– Longitudinal velocity on release fluctuates– Angular velocity on release fluctuates, whi
ch couples with beam off-centering
• d2x/dt2:– Above two effects couple with each other
• x, dx/dt, d2x/dt2 are constant in each segment
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Data processing 2
• In each segment, calculate <x>, <dx/dt>, <d2x/dt2>
• Remove them from the data
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Loss of GW signal
• A part of GW signal especially below 1 Hz is lost during the data processing 2.
• So is a part of any noise.
• S/N remains the same?
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S/N degraded below 1 Hz
Shot noise after data processing
Original shot noise
0.1 1 10 Frequency [Hz]
10-15
10-16
10-17
10-18
10-19
10-20
Displacement [mHz-1/2]
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Juggling interferometer prototype
Mo
ving
up
and
d
ow
n
TimeP
osi
tio
n
~ 2
m
Re
lea
se H
old
Co
ntin
ually
Freely fallin
g
~ 1 sec
Clamp
Re
lea
se H
old
Re
lea
se H
old