Transcript G060291-00 - DCC

Status of Ground-based
Gravitational Wave Detectors
Peter R. Saulson
Syracuse University
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Outline
1.
2.
3.
4.
5.
State of the art: bars
State of the art: interferometers
The global network
Data analysis results highlights
Near- to mid-term prospects
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Summary
Gravitational wave detectors on the ground are now
operating full-time at unprecedented sensitivity.
Detection of gravitational waves by ground based
detectors is expected, if not from this generation,
then from its successors that will start construction
within a few years.
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Quick Time™a nd a
TIFF ( Unco mpre ssed ) dec ompr esso r
ar e nee ded to see this pictur e.
Quick Time™a nd a
TIFF ( Unco mpre ssed ) dec ompr esso r
ar e nee ded to see this pictur e.
Quick Time™a nd a
TIFF ( Unco mpre ssed ) dec ompr esso r
ar e nee ded to see this pictur e.
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Resonant detectors
(or “bars”)
The original
gravitational wave
detection technology.
Now, operating at
cryogenic temperatures,
sensitivities of hrms~ 10-19 .
They are reliable and have
excellent duty cycle.
AURIGA
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Basic idea of
resonant detectors
Interaction with
gravitational wave
Vp
Rp
readout
Cd
Antenna
M
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AURIGA noise spectrum
Note success of
noise model.
AURIGA T=4.5K
-19
1x10
- noise prediction
- mechanical thermal - LC thermal
- SQUID back action - SQUID additive
-20
Shh
0.5
-1/2
[Hz ]
1x10
-21
1x10
-22
1x10
800
850
900
950
1000
Frequency [Hz]
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AURIGA output histogram
From IGEC2 events lists of 6 months (May-Nov 2005)

• Duty time 96.6% (after epoch vetoes)
• 45 events/hour @ 4.5<SNR<6 (most from thermal noise
background) as predicted by a gaussian noise simulation
• Few events @ SNR > 6 per day
• Only 85 very large events with SNR> 30
• Event lists ready for IGEC2 coincidence analysis
Amplitude of a 1ms burst
SNR=4.5 → h ~1.4 10 -18
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Explorer/Nautilus
-17
10
-18
10
-19
10
-20
10
-21
10
-22
Calibration signal
S
h
1/2
[Hz
-1/2
]
10
Explorer at T= 3 K
Nautilus at T= 3.5 K
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840
880
920
f (Hz)
960
1000
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ALLEGRO, status 2006
Running with 97%
duty factor,
since March 2004
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ALLEGRO Sensitivity
Blue - 2003
Red - 2004-now
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Global Network of
Interferometers
LIGO
GEO
Virgo
TAMA
AIGO
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Status of interferometers
The global network of 2006 – 2008 will center on LIGO,
GEO, and Virgo.
LIGO: 3 interferometers at 2 4 km sites
(Hanford WA and Livingston LA)
GEO: 600 m interferometer near Hannover
Virgo: 3 km interferometer near Pisa
TAMA 300 (Japan) has operated well, and is now
undergoing upgrades.
AIGO (Australia) is a lab for advanced interferometer
technology, and (it is hoped) a site for a future large
interferometer.
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LIGO
(here, LIGO Livingston Observatory)
A 4-km Michelson
interferometer, with
mirrors on pendulum
suspensions.
Site at Hanford WA
has both 4-km and 2km.
Scientific operations
began Nov 2005, at
design sensitivity:
hrms = 10-21.
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LIGO Hanford Observatory
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LIGO Optical Configuration
Power Recycled
Michelson
Interferometer
with Fabry-Perot
Arm Cavities
End Test Mass
4 km Fabry-Perot
arm cavity
Recycling
mirror
Input Test
Mass
225 W
Laser
15000 W
5W
signal
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50/50 beam splitter
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LIGO Beam Tube
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LIGO Vacuum Equipment
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Seismic Isolation
stack of
masssprings
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Mirror Suspensions
10 kg Fused Silica, 25 cm diameter and 10 cm thick
magnet
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LIGO sensitivity over time
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Recent noise budget,
Livingston 4 km interferometer
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GEO 600
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GEO600 optical layout
600m
interferometer with
dual recycling
mode cleaner
12W laser
detector
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GEO all-silica pendulum
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ASD [h / Hz]
GEO Sensitivity
in Science Runs
10
-16
10
-17
10
-18
10
-19
10
-20
10
-21
10
-22
10
-23
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Typical Sensitivity: Science Runs
S1 Aug 26 `02
S3I Nov 5 `03
S3II Dec 31 `03
S4 Feb 22 `05
S5 N&W Mar 23 `06
S5 24/7 May '06
GEO Design 550Hz
10
2
Freq. [Hz]
10
3
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GEO status
• Within ~x3 of design sensitivity over wide band.
• Now engaged in full-time observing.
• Another commissioning period in late 2006 to reach
design sensitivity.
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EGO
•
•
•
•
•
•
LAPP - Annecy
INFN - Firenze/Urbino
INFN - Frascati
IPN - Lyon
INFN - Napoli
OCA - Nice
•
•
•
•
•
ESPCI - Paris
LAL - Orsay
INFN - Perugia
INFN - Pisa
INFN – Roma
NIKHEF – Amsterdam (joining)
Inaugurated July 2003
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Virgo Optical Scheme
Input Mode Cleaner
3 km long Fabry-Perot cavities:
to lengthen the optical path to
100 km
Laser 20 W
Output Mode Cleaner
Power recycling mirror:
to increase the light power
to ~1 kW
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Virgo
Super-Attenuator
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Virgo commissioning started in 2003:
fast progress, approaching design sensitivity
NS/NS maximum range  1.5 Mpc
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Virgo status
• Now in commissioning.
• Expecting to be within ~x2 of design sensitivity by
Fall 2006, then will commence observing.
• Another commissioning period in first half of 2007 to
reach design sensitivity.
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Observations with
the Global Network
• Several km-scale
detectors, bars now
in operation
• Network gives:
»
»
»
»
»
Detection
confidence
Sky coverage
Duty cycle
Direction by
triangulation
Waveform
extraction
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AURIGA, Nautilus,
Explorer bars
ALLEGRO
Baton Rouge LA
1 Bar detector
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Plans for the
global network
• GEO and LIGO carry out all observing and data
analysis as one team, the LIGO Scientific
Collaboration (LSC).
• LSC and Virgo have almost concluded negotiations
on joint operations and data analysis.
• This collaboration will be open to other
interferometers at the appropriate sensitivity levels.
We will also carry out joint searches with the network
of resonant detectors.
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The S5 science run
Now, that LIGO has reached design sensitivity, we are
collecting data.
Previous science runs had durations of only one or two
months. Produced a number of upper limit papers.
S5 is intended to collect one year of integrated
coincident data at design sensitivity.
S5 began in November 2005.
Calendar duration depends on duty cycle.
Duty cycle goal is ~70% for triple coincidence.
So far, we have achieved about 45%.
GEO has recently joined S5 full time, after
commissioning and evening/weekend running.
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Neutron star binary
inspiral range vs. date
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Coincidence fraction
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Past burst upper limits,
bars and interferometers
Bars work
together as
IGEC. New
results are
expected soon.
IGEC 2
LIGO 2003 burst
search
surpassed bars’
sensitivity, but
had short
observing time.
Sensitivity now
over x10 better,
integrating for
1 year.
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Untriggered Burst Search
No gravitational wave bursts detected during S1, S2, S3, and S4.
Upper limits set on burst rate and strength from S1, S2, and S4.
Science Run 4
Detection Efficiency
Central
Frequency
hrss   h(t) dt
Rapid (high threshold) analysis of first few months of S5 has also not
yielded any detections of gravitational wave bursts.
2
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Results from
S4 Stochastic Search
•
Weighted average of H1-L1 and H2-L1
measurements:
Ω  σΩ = (-0.8  4.3) × 10-5
•
Bayesian 90% UL:
» Use S3 posterior distribution for S4
prior.
» Marginalized over calibration
uncertainty with Gaussian prior (5%
for L1, 8% for H1 and H2).
Ω90% = 6.5 × 10-5
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S5 upper limits on
signals from known pulsars
Closest to spin-down upper
limit:
Crab pulsar, only ~ 2.1 times
greater than spin-down
h0 = 3.0x10-24,
= 1.6x10-3
(fgw = 59.6 Hz, dist = 2.0 kpc)
We should have sensitivity below
spin-down limit on the Crab
pulsar before S5 is over.
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Coming Soon:
Advanced LIGO
Much better sensitivity:
• ~10x lower noise
• ~4x lower frequency
• tunable
Initial LIGO
Through these features:
• Fused silica multi-stage
suspension
• ~20x higher laser power
• Active seismic isolation
• Signal recycling
• Quantum engineering
Advanced LIGO
rad’n pressure vs. shot noise
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Reach of
advanced interferometers
Advanced LIGO and its
cousins (Advanced Virgo,
LCGT) are expected to
see lots of signals.
• Neutron star binaries
»
»
Range =350Mpc
N ~ 2/(yr) – 3/(day)
• Black hole binaries
»
»
Range=1.7Gpc
N ~ 1/(month) – 1/(hr)
LIGO Range
• BH/NS binaries
» Range=750Mpc
» N ~ 1/(yr) – 1/(day)
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Image: R. Powell
Advanced LIGO Range
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Status of Advanced LIGO
PPARC is funding substantial U.K. contribution (£8M),
including multi-stage fused silica test mass suspensions.
Max Planck Society has endorsed major German
contribution,
with value comparable to U.K.’s contribution,
including 200 W laser.
U.S. National Science Board approved Advanced LIGO.
We hope funds are included the next U.S. budget.
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Advanced LIGO
Seismic Isolation
3 stages of active seismic isolation,
plus 4 stages of passive isolation,
with fused silica pendulum suspension.
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Other plans for the
Advanced Interferometer era
• Advanced Virgo will be built on the same time scale
as Advanced LIGO, and will achieve comparable
sensitivity.
• Japan’s Large Cryogenic Gravitational Telescope
(LCGT) will pioneer cryogenics and underground
installation.
• GEO HF will improve the sensitivity beyond
GEO 600’s, mainly at high frequency where shorter
length is not an issue.
• Resonant DUAL technology could equal or surpass
that of interferometers at high frequencies.
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The DUAL concept
Read the differential
deformations of two
nested resonators
The outer
resonator is
driven above
resonance
π Phase
difference
The inner
resonator is
driven below
frequency
3-5 kHz
Intermediate
GW broadband
- gw signals add - back action noises subtract LIGO-G060291-00-Z
Advanced detectors,
next decade
-1/2)
h (Hz
h/ĆHz
Pulsars
-20
10
2012-2018 Network
LCGT-I h , 1 year integration
max
BH-BH Merger
Oscillations
@ 100 Mpc
-21
10
QNM from BH Collisions,
100 - 10 Msun, 150 Mpc
BH-BH Inspiral, 100 Mpc
Core Collapse
@ 10 Mpc
-22
10
BH-BH Inspiral,
z = 0.4
QNM from BH Collisions,
1000 - 100 Msun, z=1
-6
NS, =10 , 10 kpc
NS-NS Inspiral, 300 Mpc
-23
10
-24
10
Advanced
Virgo
Advanced
LIGO
3rd Generation ITF
-25
10
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100
1000
Hz
1048
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Summary
Gravitational wave detectors on the ground are now
operating full-time at unprecedented sensitivity.
Detection of gravitational waves by ground based
detectors is expected, if not from this generation,
then from its successors that will start construction
within a few years.
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