Advanced Gravitational-wave Detectors and LIGO-India Stan Whitcomb LIGO/Caltech 22 October 2011...

Advanced Gravitational-wave Detectors and LIGO-India

Stan Whitcomb LIGO/Caltech

22 October 2011

LIGO-G1101163-v1

LIGO-India, October 2011 2

Astrophysical Sources for Terrestrial GW Detectors

• Compact binary inspiral: “chirps”» NS-NS, NS-BH, BH-BH

• Supernovas or GRBs: “bursts”» GW signals observed in coincidence

with EM or neutrino detectors

• Pulsars in our galaxy: “periodic waves”» Rapidly rotating neutron stars

» Modes of NS vibration

• Cosmological: “stochastic background”» Probe back to the Planck time (10-43 s)

LIGO-G1101163-v1


Suspended mirrors act as “freely-falling” test masses

in horizontal plane forfrequencies f >> fpend

Terrestrial detector,L ~ 4 kmFor h ~ 10–22 – 10–21 (Initial LIGO)L ~ 10-18 m Useful bandwidth 10 Hz to 10 kHz,determined by “unavoidable” noise (at low frequencies) and expected maximum source frequencies (high frequencies)

Detecting GWs with Interferometry

LLh /

LIGO-G1101163-v1


Laser Interferometer Gravitational-wave Observatory (LIGO)

3008 km(±10 ms)

CALTECHPasadena

MITBoston

HANFORDWashington

LIVINGSTONLouisianaLIGO-G1101163-v1


end test mass

beam splittersignal

Optical Configuration

Laser

MichelsonInterferometer

MichelsonInterferometer

input test massLight is “recycled” about 50 times

Power Recycled

with Fabry-Perot Arm Cavities

Light bounces back and forth along arms about 100 times

LIGO-G1101163-v1


Initial LIGO Sensitivity Goal

• Strain sensitivity <3x10-23 1/Hz1/2

at 200 Hz Sensing Noise

» Photon Shot Noise

» Residual Gas

Displacement Noise» Seismic motion

» Thermal Noise

» Radiation Pressure

LIGO-G1101163-v1


LIGO Sensitivity

LIGO-G1101163-v1


What’s next for LIGO? Advanced LIGO

• Take advantage of new technologies and on-going R&D» Active anti-seismic system operating to lower frequencies

» Lower thermal noise suspensions and optics

» Higher laser power

» More sensitive and more flexible optical configuration

x10 better amplitude sensitivity

x1000 rate=(reach)3

1 day of Advanced LIGO

» 1 year of Initial LIGO !

2008 fabrication start,installation began 2011

LIGO-G1101163-v1


101

102

103

10-24

10-23

10-22

Frequency (Hz)

Str

ain

No

ise,

h(f

) /H

z1/2

Advanced LIGO Performance

• Newtonian background,estimate for LIGO sites

• Seismic ‘cutoff’ at 10 Hz

• Suspension thermal noise

• Test mass thermal noise

• Quantum noise dominates at most frequencies

10 Hz 100 Hz 1 kHz

10-22

10-23

10-24

10-21

Initial LIGO

Advanced LIGO

Str

ain

LIGO-G1101163-v1


Initial LIGO Laser

Custom-built10 W

Nd:YAGLaser

Stabilization cavities

for frequency and beam shape

LIGO-G1101163-v1


Advanced LIGO Laser

• Designed and contributed by Albert Einstein Institute

• Higher power» 10W -> 180W

• Better stability» 10x improvement in intensity and frequency stability

LIGO-G1101163-v1


Initial LIGO Mirrors

• Substrates: SiO2» 25 cm Diameter, 10 cm thick» Homogeneity < 5 x 10-7

» Internal mode Q’s > 2 x 106

• Polishing» Surface uniformity < 1 nm rms

( / 1000)» Radii of curvature matched < 3%

• Coating» Scatter < 50 ppm» Absorption < 2 ppm» Uniformity <10-3

• Production involved 5 companies, CSIRO, NIST, and LIGO

LIGO-G1101163-v1


Advanced LIGO Mirrors

• Larger size» 11 kg -> 40 kg

• Smaller figure error» 0.7 nm -> 0.35 nm

• Lower absorption» 2 ppm -> 0.5 ppm

• Lower coating thermal noise

• All substrates delivered

• Polishing underway

• Reflective Coating process starting upLIGO-G1101163-v1


Initial LIGO Vibration Isolation

102

100

10-2

10-4

10-6

10-8

10-10

Horizontal

Vertical

10-6

HAM stackin air

BSC stackin vacuum

LIGO-G1101163-v1


Advanced LIGO Seismic Isolation

• Two-stage six-degree-of-freedom active isolation» Low noise sensors, Low noise actuators

» Digital control system to blend outputs of multiple sensors, tailor loop for maximum performance

LIGO-G1101163-v1


Initial LIGO Test Mass Suspension

• Simple single-loop pendulum suspension

• Low loss steel wire» Adequate thermal noise performance,

but little margin

• Magnetic actuators for control

LIGO-G1101163-v1


Advanced LIGO Suspensions

• UK designed and contributed test mass suspensions

• Silicate bonds create quasi-monolithic pendulums using ultra-low loss fused silica fibers to suspend interferometer optics» Pendulum Q ~105 -> ~108

17

40 kg silica test mass

four stages

LIGO-G1101163-v1

A Global Array of GW Detectors:Source Localization

• Locate sources using multi-site arrival times (“aperture synthesis”)

LIGO-India, October 2011

LIGOGEO Virgo

LCGT

1 2

L =

c t

18LIGO-G1101163-v1


LIGO and Virgo Alone

Planned detector network has limited ability to locate sources, particularly

near the celestial equator

LIGO-G1101163-v1


LIGOGEO Virgo

TAMA/LCGT

LIGO-India

Completing the Global Network

LIGO-G1101163-v1


LIGO and Virgo Plus LIGO-India

Adding LIGO-India to existing network gives nearly all-sky coverage

LIGO-G1101163-v1


LIGO and Virgo Alone

LIGO-G1101163-v1


LIGO-India Concept

• A direct partnership between LIGO Laboratory and IndIGO to build an Indian interferometer» LIGO Lab (with its UK, German and Australian partners) provides

components for one Advanced LIGO interferometer, unit #3, from the Advanced LIGO project

» India provides the infrastructure (site, roads, building, vacuum system), “shipping & handling,” staff, installation & commissioning, operating costs

• The interferometer, the third Advanced LIGO instrument, would be operated as part of LIGO to maximize the scientific impact of LIGO-India

• Key deadline: LIGO needs a commitment from India by March 2012—otherwise, must begin installation of the LIGO-India detector at our US facility

LIGO-G1101163-v1

What Does India Provide?

• Participation in Advanced LIGO installation and commissioning in US» Training, but also early participation in detector development

• Site» LIGO provides requirements and its design

• Buildings» LIGO provides requirements and its design

• Vacuum system» LIGO provides detailed drawings for up-dating, assistance for

achieving low out-gassing performance

• Staff to install, commission and operate» LIGO provides training for Indian staff, collaboration and support

• All data are shared throughout the collaboration

LIGO-India, October 2011 24LIGO-G1101163-v1


LIGO Livingston Observatory

LIGO-G1101163-v1

India provides a facility with- Vacuum system Site, buildings


LIGO Beam Tube

• LIGO beam tube under construction in January 1998

• 16 m spiral welded sections

• girth welded in portable clean room in the field

1.2 m diameter - 3mm stainless50 km of weld

NO LEAKS !!LIGO-G1101163-v1


LIGO Vacuum Equipment

LIGO-G1101163-v1


Corner Station Chambers

• Align, assemble, test under portable clean rooms

LIGO-G1101163-v1


Beamtube Gate Valves

• Large gate valves to isolatebeamtubes,LN2 traps

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Detector Installation using Cleanrooms

• Chamber access through large doors

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HAM Chamber

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Optics Installation Under Cleanroom Conditions

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LIGO Lab Concerns:Who Does it?

• Number of experienced interferometer experts is small» Initially, IndIGO mostly theorists or data analysts

» Growing interest from experimental community, but still new to GWs

» August: Rana Adhikari visit to India to assess capability and to recruit

• Expect to have a training program in LIGO for interferometer specialists» Started last year in anticipation of LIGO-Australia

» Working to recruit postdocs to work with LIGO (2 so far)

• Need to identify Project team» Most likely source from National Labs or Centres

» Requires official standing with government departments for commitments, but some expressions of support


LIGO Lab Concerns :Site

• So far, no definite site identified and characterized

• In terms of ‘Science’, specific location with in India (including orientation) is not critical» Result of simulation studies by Sathya et al.

• Site selection guidance given to IndIGO» Data collection could take some months

• My opinion: I expect that finding a suitable site is possible (requirements are not that extreme) » Difficult issues will be ability to secure it and timescale

» Discussions about possible site hampered initially by lack of approved project status


NSF Review of LIGO-India

• Blue-ribbon panel to judge science case and to advise on possible implementation issues

• Provided with background documents and met Oct 7 (via internet) for ~6 hours of presentation/ discussion

• Summary finding:“The panel believes that the science case for LIGO-India is

compelling, and reason enough to move forward in the near term with the understanding that there are a number of outstanding issues with funding, site selection, and the selection of institutional leadership, top management and technical expertise that must be resolved before making a deeper commitment.

“We note that LIGO-India is the only option actively under consideration by the LIGO Laboratory.”

LIGO-G1101163-v1 LIGO-India, October 2011 36

Where from Here?

• Intense evaluation by LIGO Lab over next six months

• Group of senior LIGO Lab scientists to India in mid-October (this visit)» Meet potential participants and laboratory directors to assess

capabilities and interest (follow-up to Rana’s visit, ‘measure first derivative’)

» Understand project capabilities in national labs

» Visit potential site

• Attempt to arrange visit from vacuum system company representatives to LIGO facility

• Continuing “training program”» Second Indian postdoc starts at Caltech

» Applications for next year now open

» Measure of momentum in forming core team


Where from Here?(continued)

• IGC2011 conference in Goa, Workshop in Pune in December--next opportunity for face-to-face meetings» Number of LIGO Lab and LSC attendees

» NSF Assistant Director Ed Seidel also planning to go

• Stay engaged in planning process in India» Assist with Detailed Project Report (proposal)

» Provide information, as needed

• Consult people with experience in collaborating with India to assess export control issues» Fermilab, TMT, others?

• Planning for a final “go/no-go” visit to India in February» Best assessment of how far have we gotten

» Funding status, likely lead lab, perhaps some key personnel


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Advanced Gravitational-wave Detectors and LIGO-India Stan Whitcomb LIGO/Caltech 22 October 2011...

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