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Advanced LIGO and

the 2nd generation of gravitational waves observatories

Giacomo Ciani for the

LIGO Scientific Collaboration

LIGO-G1101293

• GW and laser interferometers

• The first generation of detectors

• Towards advanced detectors

• Advanced detectors network

• What’s next?

• Summary

Dec 19th, 2011 – CGC Conference in Fort Lauderdale Giacomo Ciani for the LSC LIGO-G1101293

Overview

2

• Who says GWs exist? – Predicted by General Relativity

– Hulse-Taylor: indirect evidence by binary pulsar spin-down (Nobel Prize 1993)

• What are gravitational waves? – Ripple in space-time travelling at the speed

of light

• Who creates GWs? – Mass distributions changing in a non-

spherically symmetric way (e.g. binary systems)

• What is their effect? – Relative change in lengths orthogonal to

propagation direction

– The effect is VERY small: typical size


FAQs on gravitational waves

3

Relic radiation Cosmic Strings

Supermassive BH Binaries

BH and NS Binaries

Binaries coalescences

Extreme Mass Ratio Inspirals

A whole orchestra on the stage


10-9 Hz 10-4 Hz 100 Hz 103 Hz 10-16 Hz

Supernovae

Spinning NS

4

And a microphone for everyone


10-9 Hz 10-4 Hz 100 Hz 103 Hz

Relic radiation Cosmic Strings

Supermassive BH Binaries

BH and NS Binaries

Binaries coalescences

Extreme Mass Ratio Inspirals

Supernovae

Spinning NS

10-16 Hz

Inflation Probe Pulsar timing Space detectors Ground interferometers

5

DL

PP

D

• Inherently differential

• Broad band

• Long baseline


Laser interferometers

Laser

“+” polarized GW propagating

orthogonal to the screen

Phase: f = 4p (Lx – Ly) /l ~ DL Power: PPD = PBS sin2f

6

Initial detectors era: Initial LIGO


Laser

Laser: 10W - 1064nm

Input mode cleaner: stabilizes frequency

and clean laser mode

Arm cavities: Faby-Perrot cavities

store light to effectively increase

length

RF Heterodyne Readout

Power recycling mirror: reflects back light coming

from the beam splitter, increasing power in the

arm cavities

Input Test

Mass

End Test

Mass

4 km

4 km

10kW 1

0kW

7

iLIGO strain sensitivity


Now Inauguration First Lock Full Lock all IFO

4K strain noise

@150 Hz [Hz-1/2]

3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4

1999 2000 2001 2002 2003 2004 2005 2006

1 2 3 4

2007

1 2 3 4

2008

1 2 3 4

2009

1 2 3 4

2010

1 2 3 4

2011

Design Sensitivity

10-17 10-18 10-20 10-21 10-22 3x10-23

Enhanced LIGO

Seismic noise (displacement): mechanical vibration of the ground transmitted to the mirror through the pendulum chain

Suspension thermal (displacement): thermal agitation induce noise in mirror motion

Shot noise (detection): random arrival of photons creates noise at high frequencies

8

PLUS:

• Better input optic to handle higher power

• Upgraded Thermal Compensation System to correct thermal distortions and lensing

• In-vacuum readout components


An intermediate step: Enhanced LIGO

Laser

4 km

4 km Laser:

10W - 1064nm

Output mode cleaner: Reject junk light to clean signal on photodetector

DC Homodyne Readout

10kW 1

0kW

9

PLUS:

• Better input optic to handle higher power

• Upgraded Thermal Compensation System to correct thermal distortions and lensing

• In-vacuum readout components


An intermediate step: Enhanced LIGO

Laser

4 km

4 km Laser:

10W - 1064nm

Output mode cleaner: Reject junk light to clean signal on photodetector

DC Homodyne Readout

10kW 1

0kW

102

103

10-23

10-22

Frequency [Hz]

h(f

) [H

z-1

/2]

10

All the actors on the scene


TAMA300

LIGO Hanford (2 IFOs)

LIGO Livingston

VIRGO

GEO600

11

• More than 60 LSC-authored papers on S1..S5: – “Implications for the Origin of GRB 070201 from LIGO Observations”,

Astrophys. J. 681 (2008) 1419 – “Beating the spin-down limit on gravitational wave emission from the

Crab pulsar”, Astrophys. J. Lett. 683 (2008) 45 – “An upper limit on the stochastic gravitational-wave background of

cosmological origin”, Nature 460 (2009) 990 – …and many more…

• Many LSC-authored articles on S6, published or to be published soon:

– “A gravitational wave observatory operating beyond the quantum shot-noise limit”, Nat Phys online: doi:10.1038/nphys2083

– “All-sky search for periodic gravitational waves in the full S5 LIGO data”, arXiv:1110.0208

• Created expertise in design, commissioning and operation of large scale

interferometric detectors

• Created a strong international community – The LIGO and VIRGO scientific collaborations work now in full synergy

(data analyzed jointly since 2007)


Initial/Enhanced detectors results

First Science Data

S1 S4 LIGO Science

Runs

S2

S6 ends 10/20/2010

S3 S5 S6

1 year of Coincidence Data 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4

1999 2000 2001 2002 2003 2004 2005 2006

1 2 3 4

2007

1 2 3 4

2008

1 2 3 4

2009

1 2 3 4

2010

1 2 3 4

2011

Enhanced LIGO

12

http://www.iop.org/EJ/abstract/0004-637X/681/2/1419/





http://www.iop.org/EJ/abstract/1538-4357/683/1/L45/







http://www.nature.com/nature/journal/v460/n7258/pdf/nature08278.pdf




http://www.nature.com/nphys/journal/vaop/ncurrent/full/nphys2083.html

http://arxiv.org/abs/1110.0208

• More than 60 LSC-authored papers on S1..S5: – “Implications for the Origin of GRB 070201 from LIGO Observations”,

Astrophys. J. 681 (2008) 1419 – “Beating the spin-down limit on gravitational wave emission from the

Crab pulsar”, Astrophys. J. Lett. 683 (2008) 45 – “An upper limit on the stochastic gravitational-wave background of

cosmological origin”, Nature 460 (2009) 990 – …and many more…

• Many LSC-authored articles on S6, published or to be published soon:

– “A gravitational wave observatory operating beyond the quantum shot-noise limit”, Nat Phys online: doi:10.1038/nphys2083

– “All-sky search for periodic gravitational waves in the full S5 LIGO data”, arXiv:1110.0208

• Created expertise in design, commissioning and operation of large scale

interferometric detectors

• Created a strong international community – The LIGO and VIRGO scientific collaborations work now in full synergy

(data analyzed jointly since 2007)


Initial/Enhanced detectors results

First Science Data

S1 S4 LIGO Science

Runs

S2

S6 ends 10/20/2010

S3 S5 S6

1 year of Coincidence Data 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4

1999 2000 2001 2002 2003 2004 2005 2006

1 2 3 4

2007

1 2 3 4

2008

1 2 3 4

2009

1 2 3 4

2010

1 2 3 4

2011

Enhanced LIGO

13

















http://www.nature.com/nphys/journal/vaop/ncurrent/full/nphys2083.html


Advanced detectors: the big step

• Re-use existing facilities • 10 times better in strain (15->150 Mpc fro NS-NS)

– 1000x improvement in observable volume (= rate)

• Improvement at low frequency (from 40 to 10 Hz) – Increase type (higher masses) and number of sources – Increase signal “in-band” time

• Limited by fundamental noise: quantum, thermal • Tunable


10-24

10-23

10-22

10-21

10-20

10-19

Str

ain

(1

/ Hz)

101

2 3 4 5 6 7 8 9

102

2 3 4 5 6 7 8 9

103

2 3 4 5 6 7 8 9

104

Frequency (Hz)

Hanford 4 km S6

Livingston 4 km S6

AdvLIGO, No Signal Recycling (early operation)

AdvLIGO, Zero Detuning (Low Power)

AdvLIGO, ZeroDetuning (High Power)

AdvLIGO, NS-NS optiimized AdvLIGO, High Frequency Detuning

Initial

LIGO

Advanced

LIGO

Abadie, et al. “Predictions for the Rates of Compact Binary Coalescences Observable by Ground-based Gravitational-wave Detectors” CQG 27 173001 (2010), arXiv:1003.2480

Neutron Star (NS) = 1.4 M

, Black Hole (BH) = 10 M

Routine detection not certain, but plausible!

14


Advanced LIGO: key improvements


Input Laser Mirrors Topology Readout Sensitivity Seismic isolation

iLIGO 10W

(10 kW arm) 10 kg

Power-Recycled Fabry-Perot

RF etherodyne

3 10-23 Hz-1/2 Single pendulum (LF cutoff ~40 Hz)

aLIGO 180W

(>700 kW arm) 40 kg

Dual-Recycled Fabry-Perot

DC homodyne

5 10-24 Hz-1/2 broadband (tunable)

Quadruple pendulum (LF cutoff ~10 Hz)

15




iLIGO 10W

(10 kW arm) 10 kg


RF etherodyne


aLIGO 180W

(>700 kW arm) 40 kg


DC homodyne



16




iLIGO 10W

(10 kW arm) 10 kg


RF etherodyne


aLIGO 180W

(>700 kW arm) 40 kg


DC homodyne



New Test Masses: • 40 kg • 38 cm in diameter • Polishing: 0.15 nm rms • Coating absorption: 0.5 ppm

-1 nm

1 nm

17


Advanced LIGO: key improvements Input Laser Mirrors Topology Readout Sensitivity Seismic isolation

iLIGO 10W

(10 kW arm) 10 kg


RF etherodyne


aLIGO 180W

(>700 kW arm) 40 kg


DC homodyne



Signal recycling cavity: Resonant for the sidebands created

by GW signal

18

• Two stage active pre-isolation

• 4 stage TM supension with reaction chain

• Last stage: monolitic fused silica



iLIGO 10W

(10 kW arm) 10 kg


RF etherodyne


aLIGO 180W

(>700 kW arm) 40 kg


DC homodyne



ISI: Internal Seismic Isolator

HEPI: Hydraulic External Pre-Isolator

HAM Chambers isolation

19




iLIGO 10W

(10 kW arm) 10 kg


RF etherodyne


aLIGO 180W

(>700 kW arm) 40 kg


DC homodyne



20



iLIGO 10W

(10 kW arm) 10 kg


RF etherodyne


aLIGO 180W

(>700 kW arm) 40 kg


DC homodyne



Initia

l

LIGO

Seismic cu

toff

21

• About 60% done: – Removal of initial LIGO complete for two interferometers – Almost all Advanced LIGO equipment contracted for production – A lot of equipment – almost all Seismic and Suspension parts – made; DAQ installed and running;

2km test mass chambers moved 4km – PSL installed at LLO and one of the LHO IFOs

• Some delays: fabrication difficulties (vacuum equipment, suspension parts, optics), puzzles in

testing, assembly, chamber cleaning. Mostly overcome. • Despite delays, still 5 months ahead of NSF schedule

• Integrate One Arm Test to occur March, 2012:

– A complete, single arm assembled and locked as a stand-alone cavity – Will test main isolation hardware and locking scheme

• Current plan to have interferometers accepted (2 hour lock) July 2014


To road to Advanced LIGO

3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4

2012 2013 2014 2015 2016 2017 2018 2006

1 2 3 4

2007

1 2 3 4

2008

1 2 3 4

2009

1 2 3 4

2010

1 2 3 4

2011

aLIGO

project starts

Observatories

hand-off to aLIGO

Integrated

One Arm Test

1st IFO

accepted

2nd and 3rd IFOs

accepted

GW Astronomy begins!

Right now

>60% complete

Dark Era S6 S5 eLIGO inst.

22

• Located in Italy • Operated by European

Consortium • 3 km arm length • Similar design to aLIGO:

– limited by fundamental noise – unique SuperAttenuator

design

• Expected online in 2015 (same as aLIGO)


Other detectors: AdVIRGO credits:

Giovanni LOSURDO & Jean-Yves VINET / VIRGO

23 23

• Located in Kamyoka mines, Japan

• 3 km arm length

• Pioneering in next generation technologies: – Underground

– Cryogenics

– Alternative materials

• Two phases: full sensitivity expected in 2017


Other detectors: LCGT

24

• Locate in Hannover, Germany • Part of the LIGO collaboration • 600 m baseline • Limited sensitivity as low frequencies • Pioneers advanced techniques:

– Squeezing – Signal recycling – More…

• The only listener until 2015!


Other detectors: GEO HF

25

• Proposal: move one of the Hanford detectors to Australia – ACIGA to provide:

• Infrastructures (including vacuum system)

• Staff for routine operation

– LIGO to provide: • Detector components

• Assistance for installation and commissioning


The case of LIGO Australia

26

• Increased sky coverage

• Greatly enhanced sky localization

• Increase duty cycle

• Decoupling of local noise for 3rd LIGO detector



27



• LIGO Australia didn’t happen due to budget constraints in Australia

• A similar proposal for India is now under investigation: – NFS reviewed the scientific case: found compelling

– Deadline for India commitment: March 2012

• Scientific advantage would be comparable – Even better if we include LCGT

28

All the actors on the scene


aLIGO Hanford 2015

aLIGO Livingston 2015

AdVIRGO 2015

GEO600 Now!

LCGT 2017

Increased detection confidence (coincidence runs)

Reduced downtime

Enhanced sky coverage Better and faster source localization

More reliable source parameters estimation

LIGO India 2020?

29

• Go underground (LCGT) – Easy… but expensive!

• Band- specific detectors – Less easy… still expensive!

• Go cryogenic (LCGT) – New material – New lasers – Cooling… quietly!

• Fight coating thermal noise: – Low-loss (crystalline?)

coatings – Gratings – Exotic beam profiles

• Beat the Standard Quantum Limit! – Frquency-dependent

squeezing – Ponderomotive squeezing


Farther down the road…

See “Einstein gravitational wave Telescope conceptual design study”

https://tds.ego-gw.it/itf/tds/index.php?callContent=2&callCode=8709

30

• Squeezing: – Vacuum fluctuations creates noise at the

“dark” port

– Injecting 3 dB of squeezed light (“vacuum”, actually) is equivalent to 2x increase in power

– Demonstrated in GEO (6 dB) and recently in H1 (>2 dB)

• Newtonian noise subtraction – Noise due to local gravitational field

variations might already show up in aLIGO

– Can be subtracted by accurate modeling and monitoring of sources


… or just around the corner

31

• Initial generation of interferometers: – No detection

– Many significant scientific results

– Training bench for the advanced detectors

– Built a strong worldwide GW community

• Advanced detector: – Construction well under way

– aLIGO and adVirgo expected online 2015

– Others to join the network soon after

– “GW astronomy era” at hand

• In the meanwhile, plans are underway for the development of the next generation of detector


All in one slide

32

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