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Advanced Gravitational-wave Detectors and LIGO-India Stan Whitcomb LIGO/Caltech 22 October 2011 LIGO-G1101163-v1.

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Presentation on theme: "Advanced Gravitational-wave Detectors and LIGO-India Stan Whitcomb LIGO/Caltech 22 October 2011 LIGO-G1101163-v1."— Presentation transcript:

1 Advanced Gravitational-wave Detectors and LIGO-India Stan Whitcomb LIGO/Caltech 22 October 2011 LIGO-G v1

2 LIGO-India, October 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 ( s) LIGO-G v1

3 LIGO-India, October Suspended mirrors act as “freely-falling” test masses in horizontal plane for frequencies f >> f pend Terrestrial detector, L ~ 4 km For h ~ 10 –22 – 10 –21 (Initial LIGO)  L ~ 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 LIGO-G v1

4 LIGO-India, October Laser Interferometer Gravitational-wave Observatory (LIGO) LIGO-G v1

5 LIGO-India, October end test mass beam splitter signal Optical Configuration Laser Michelson Interferometer Michelson Interferometer input test mass Light is “recycled” about 50 times Power Recycled with Fabry-Perot Arm Cavities Light bounces back and forth along arms about 100 times LIGO-G v1

6 LIGO-India, October Initial LIGO Sensitivity Goal Strain sensitivity <3x /Hz 1/2 at 200 Hz Sensing Noise »Photon Shot Noise »Residual Gas Displacement Noise »Seismic motion »Thermal Noise »Radiation Pressure LIGO-G v1

7 LIGO-India, October LIGO Sensitivity LIGO-G v1

8 LIGO-India, October 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-G v1

9 LIGO-India, October 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 Hz100 Hz 1 kHz Initial LIGO Advanced LIGO Strain LIGO-G v1

10 LIGO-India, October Initial LIGO Laser Custom-built 10 W Nd:YAG Laser Stabilization cavities for frequency and beam shape LIGO-G v1

11 LIGO-India, October Advanced LIGO Laser Designed and contributed by Albert Einstein Institute Higher power »10W -> 180W Better stability »10x improvement in intensity and frequency stability LIGO-G v1

12 LIGO-India, October Initial LIGO Mirrors Substrates: SiO 2 »25 cm Diameter, 10 cm thick »Homogeneity < 5 x »Internal mode Q’s > 2 x 10 6 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-G v1

13 LIGO-India, October 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 up LIGO-G v1

14 LIGO-India, October Initial LIGO Vibration Isolation Horizontal Vertical HAM stack in air BSC stack in vacuum LIGO-G v1

15 LIGO-India, October 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-G v1

16 LIGO-India, October 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-G v1

17 LIGO-India, October 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 ~10 5 -> ~ kg silica test mass four stages LIGO-G v1

18 A Global Array of GW Detectors: Source Localization Locate sources using multi-site arrival times (“aperture synthesis”) LIGO-India, October 2011 LIGO GEO Virgo LCGT 12   L = c  t 18 LIGO-G v1

19 LIGO-India, October LIGO and Virgo Alone Planned detector network has limited ability to locate sources, particularly near the celestial equator LIGO-G v1

20 LIGO-India, October LIGO GEO Virgo TAMA/LCGT LIGO-India Completing the Global Network LIGO-G v1

21 LIGO-India, October LIGO and Virgo Plus LIGO-India Adding LIGO-India to existing network gives nearly all-sky coverage LIGO-G v1

22 LIGO-India, October LIGO and Virgo Alone LIGO-G v1

23 LIGO-India, October 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-G v1

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 LIGO-G v1

25 LIGO-India, October LIGO Livingston Observatory LIGO-G v1

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

27 LIGO-India, October LIGO Beam Tube LIGO beam tube under construction in January 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-G v1

28 LIGO-India, October LIGO Vacuum Equipment LIGO-G v1

29 LIGO-India, October Corner Station Chambers Align, assemble, test under portable clean rooms LIGO-G v1

30 LIGO-India, October Beamtube Gate Valves Large gate valves to isolate beamtubes, LN2 traps LIGO-G v1

31 LIGO-India, October Detector Installation using Cleanrooms Chamber access through large doors LIGO-G v1

32 LIGO-India, October HAM Chamber LIGO-G v1

33 LIGO-India, October Optics Installation Under Cleanroom Conditions LIGO-G v1

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 LIGO-G v1

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 LIGO-G v1

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-G v1LIGO-India, October

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 LIGO-G v1

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 LIGO-G v1


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