Transcript Searching for GW with LIGO
Advanced Gravitational-wave Detectors and LIGO-India
LIGO-G1101163-v1
Stan Whitcomb LIGO/Caltech
22 October 2011
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
LIGO-India, October 2011
2
Detecting GWs with Interferometry
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
D
L ~ 10 -18 m – 10 –21 (Initial LIGO) Useful bandwidth 10 Hz to 10 kHz, determined by “unavoidable” noise (at low frequencies) and expected maximum source frequencies (high frequencies)
LIGO-G1101163-v1
LIGO-India, October 2011
h
D
L
/
L
3
Laser Interferometer Gravitational-wave Observatory (LIGO)
HANFORD Washington MIT Boston CALTECH Pasadena
LIGO-G1101163-v1
LIVINGSTON
4
Optical Configuration
Power Recycled Michelson Interferometer with Fabry-Perot Arm Cavities
Light is “recycled” about 50 times
Laser LIGO-G1101163-v1
end test mass Light bounces back and forth along arms about 100 times input test mass signal beam splitter
LIGO-India, October 2011
5
LIGO-G1101163-v1
Initial LIGO Sensitivity Goal
• Strain sensitivity < 3x10 -23 1/Hz 1/2 at 200 Hz Sensing Noise » Photon Shot Noise » Residual Gas Displacement Noise » Seismic motion » Thermal Noise » Radiation Pressure
LIGO-India, October 2011
6
LIGO Sensitivity
LIGO-G1101163-v1
LIGO-India, October 2011
7
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-India, October 2011
8 LIGO-G1101163-v1
Advanced LIGO Performance
• Newtonian background, estimate for LIGO sites 10 -21 • Seismic ‘cutoff’ at 10 Hz • Suspension thermal noise 10 -22
-22
Initial LIGO • • Test mass thermal noise 10 -23
-23
Advanced LIGO Quantum noise dominates at most frequencies 10 -24
-24 10 1
10 Hz
10 2
100 Hz
10 3
1 kHz LIGO-G1101163-v1
LIGO-India, October 2011
9
Initial LIGO Laser
Custom-built 10 W Nd:YAG Laser LIGO-G1101163-v1
LIGO-India, October 2011
Stabilization cavities for frequency and beam shape 10
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
LIGO-India, October 2011
11
Initial LIGO Mirrors
• • • • Substrates: SiO 2 » 25 cm Diameter, 10 cm thick » Homogeneity < 5 x 10 -7 » Internal mode Q’s > 2 x 10 6 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-G1101163-v1
LIGO-India, October 2011
12
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-G1101163-v1
LIGO-India, October 2011
13
Initial LIGO Vibration Isolation
HAM stack in air LIGO-G1101163-v1
LIGO-India, October 2011
BSC stack in vacuum 10 2 10 0 2 10 4 10 6 10 8 10 10 -10
Horizontal
10 -6
Vertical
14
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
LIGO-India, October 2011
15
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
LIGO-India, October 2011
16
four stages 40 kg silica test mass 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 ~10 5 -> ~10 8
LIGO-India, October 2011
LIGO
A Global Array of GW Detectors: Source Localization
GEO Virgo LCGT
• Locate sources using multi-site arrival times (“aperture synthesis”) LIGO-G1101163-v1
LIGO-India, October 2011
1
q
2
18
LIGO and Virgo Alone
Planned detector network has limited ability to locate sources, particularly near the celestial equator LIGO-G1101163-v1
LIGO-India, October 2011
19
LIGO
Completing the Global Network
GEO Virgo TAMA/LCGT
LIGO-G1101163-v1
LIGO-India LIGO-India, October 2011
20
LIGO and Virgo Plus LIGO-India
LIGO-G1101163-v1 Adding LIGO-India to existing network gives nearly all-sky coverage
LIGO-India, October 2011
21
LIGO and Virgo Alone
LIGO-G1101163-v1
LIGO-India, October 2011
22
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
LIGO-India, October 2011
23
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-G1101163-v1
LIGO-India, October 2011
24
LIGO
Livingston Observatory
LIGO-G1101163-v1
LIGO-India, October 2011
25
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 stainless 50 km of weld
LIGO-India, October 2011
NO LEAKS !!
27 LIGO-G1101163-v1
LIGO Vacuum Equipment
LIGO-G1101163-v1
LIGO-India, October 2011
28
Corner Station Chambers
• Align, assemble, test under portable clean rooms LIGO-G1101163-v1
LIGO-India, October 2011
29
• Large gate valves to isolate beamtubes, LN2 traps
Beamtube Gate Valves
LIGO-G1101163-v1
LIGO-India, October 2011
30
Detector Installation using Cleanrooms
• Chamber access through large doors LIGO-G1101163-v1
LIGO-India, October 2011
31
HAM Chamber
LIGO-G1101163-v1
LIGO-India, October 2011
32
Optics Installation Under Cleanroom Conditions
LIGO-G1101163-v1
LIGO-India, October 2011
33
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-G1101163-v1
LIGO-India, October 2011
34
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-G1101163-v1
LIGO-India, October 2011
35
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 LIGO-G1101163-v1
LIGO-India, October 2011
37
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-G1101163-v1
LIGO-India, October 2011
38