Advanced Gravitational-wave Detectors and LIGO-India

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

3. Detecting GWs with Interferometry Suspended mirrors act as “freely-falling” test masses in horizontal plane for frequencies f >> fpend Terrestrial detector,L ~ 4 km For h ~ 10–22 – 10–21 (Initial LIGO) DL ~ 10-18 m Useful bandwidth 10 Hz to 10 kHz, determined by “unavoidable” noise (at low frequencies) and expected maximum source frequencies (high frequencies) LIGO-India, October 2011

4. Laser Interferometer Gravitational-wave Observatory (LIGO) HANFORD Washington MIT Boston 3 0 0 ( 8 ± 1 k 0 m m s ) CALTECH Pasadena LIVINGSTON Louisiana LIGO-India, October 2011

5. Power Recycled end test mass with Fabry-Perot Arm Cavities Light bounces back and forth along arms about 100 times Light is “recycled” about 50 times beam splitter signal Optical Configuration Michelson Interferometer input test mass Laser LIGO-India, October 2011

6. Initial LIGO Sensitivity Goal • Strain sensitivity <3x10-23 1/Hz1/2at 200 Hz • Sensing Noise • Photon Shot Noise • Residual Gas • Displacement Noise • Seismic motion • Thermal Noise • Radiation Pressure LIGO-India, October 2011

7. LIGO Sensitivity LIGO-India, October 2011

8. 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 x1000rate=(reach)3  1 day of Advanced LIGO » 1 year of Initial LIGO ! 2008 fabrication start,installation began 2011 LIGO-India, October 2011

9. 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 10-21 Initial LIGO 10-22 Strain Advanced LIGO 10-23 10-24 10 Hz 100 Hz 1 kHz LIGO-India, October 2011

10. Initial LIGO Laser Stabilization cavities for frequency and beam shape Custom-built 10 W Nd:YAG Laser LIGO-India, October 2011

11. Advanced LIGO Laser • Designed and contributed by Albert Einstein Institute • Higher power • 10W -> 180W • Better stability • 10x improvement in intensity and frequency stability LIGO-India, October 2011

12. 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(l / 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-India, October 2011

13. Advanced LIGO Mirrors • All substrates delivered • Polishing underway • Reflective Coating process starting up • 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 LIGO-India, October 2011

14. 102 100 10-2 10-6 Horizontal 10-4 10-6 10-8 Vertical 10-10 Initial LIGO Vibration Isolation HAM stack in air BSC stackin vacuum LIGO-India, October 2011

15. 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-India, October 2011

16. 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-India, October 2011

17. Advanced LIGO Suspensions four stages 40 kg silica test mass • 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 LIGO-India, October 2011 17

18. DL = c dt q 1 2 A Global Array of GW Detectors:Source Localization Virgo GEO LIGO LCGT Locate sources using multi-site arrival times (“aperture synthesis”) LIGO-India, October 2011

19. LIGO and Virgo Alone Planned detector network has limited ability to locate sources, particularly near the celestial equator LIGO-India, October 2011

20. Completing the Global Network LIGO-India Virgo GEO LIGO TAMA/LCGT LIGO-India, October 2011

21. LIGO and Virgo Plus LIGO-India Adding LIGO-India to existing network gives nearly all-sky coverage LIGO-India, October 2011

22. LIGO and Virgo Alone LIGO-India, October 2011

23. 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-India, October 2011

24. 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

25. LIGO Livingston Observatory LIGO-India, October 2011

26. India provides a facility with- Vacuum system Site, buildings

27. 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 stainless 50 km of weld NO LEAKS !! LIGO-India, October 2011

28. LIGO Vacuum Equipment LIGO-India, October 2011

29. Corner Station Chambers • Align, assemble, test under portable clean rooms LIGO-India, October 2011

30. Beamtube Gate Valves • Large gate valves to isolatebeamtubes,LN2 traps LIGO-India, October 2011

31. Detector Installation using Cleanrooms • Chamber access through large doors LIGO-India, October 2011

32. HAM Chamber LIGO-India, October 2011

33. Optics Installation Under Cleanroom Conditions LIGO-India, October 2011

34. 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-India, October 2011

35. 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 LIGO-India, October 2011

36. 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-India, October 2011

37. 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 LIGO-India, October 2011

38. 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 LIGO-India, October 2011