Status of LIGO by liamei12345

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									                Status of Ground-based
              Gravitational Wave Detectors

                      Peter R. Saulson
                     Syracuse University




LIGO-G060291-00-Z
                                             1
                                Outline
   1.    State of the art: bars
   2.    State of the art: interferometers
   3.    The global network
   4.    Data analysis results highlights
   5.    Near- to mid-term prospects




LIGO-G060291-00-Z
                                             2
                      Summary
   Gravitational wave detectors on the ground are now
     operating full-time at unprecedented sensitivity.

   Detection of gravitational waves by ground based
     detectors is expected, if not from this generation,
     then from its successors that will start construction
     within a few years.




LIGO-G060291-00-Z
                                                             3
                                                                                   Q uic kT ime ™ a n d a
                                                                       T IFF ( Un co m pr e ss e d) d ec o mp r es s or
                                                                           a re n ee d ed to s e e th is p ictu r e.




                                                                                                             Q uic kT ime ™ a n d a
                                                                                                 T IFF ( Un co m pr e ss e d) d ec o mp r es
                                                                                                     a re n ee d ed to s e e th is p ictu r e.




                                Q uic kT ime ™ a n d a
                    T IFF ( Un co m pr e ss e d) d ec o mp r es s or
                        a re n ee d ed to s e e th is p ictu r e.




LIGO-G060291-00-Z
                                                                                                                             4
                      Resonant detectors
                          (or “bars”)

The original
gravitational wave
detection technology.
Now, operating at
cryogenic temperatures,
sensitivities of hrms~ 10-19 .
They are reliable and have
excellent duty cycle.



                                     AURIGA
  LIGO-G060291-00-Z
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                             Basic idea of
                          resonant detectors

                                        Interaction with
                                        gravitational wave



                              Vp

                                   Rp

          readout
                                         Cd
                    Antenna
                      M

LIGO-G060291-00-Z
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                               AURIGA noise spectrum

Note success of                            AURIGA T=4.5K                - noise prediction
noise model.                  1x10
                                     -19                        - mechanical thermal - LC thermal
                                                                - SQUID back action - SQUID additive




                                     -20
                              1x10
                      [Hz ]
                  -1/2
                  0.5
                      Shh




                                     -21
                              1x10




                                     -22
                              1x10
                                       800         850          900          950           1000
                                                           Frequency [Hz]
  LIGO-G060291-00-Z
                                                                                                       7
              AURIGA output histogram


                                From IGEC2 events lists of 6 months (May-Nov 2005)

                                • Duty time 96.6% (after epoch vetoes)
                                • 45 events/hour @ 4.5<SNR<6 (most from thermal noise
                                background) as predicted by a gaussian noise simulation
                                • Few events @ SNR > 6 per day
                                • Only 85 very large events with SNR> 30
                                • Event lists ready for IGEC2 coincidence analysis



                                               

     Amplitude of a 1ms burst
     SNR=4.5 → h ~1.4 10 -18


LIGO-G060291-00-Z
                                                                                          8
                    Explorer/Nautilus


                                          Explorer at T= 3 K              Calibration signal

                                          Nautilus at T= 3.5 K
                                    -17
                               10

                                    -18
                     ]
                    -1/2
                     [Hz       10

                                    -19
                               10
                    1/2
                           h
                     S




                                    -20
                               10

                                    -21
                               10

                                    -22
                               10
                                          840           880        920         960             1000
LIGO-G060291-00-Z                                                f (Hz)                           9
                    ALLEGRO, status 2006

Running with 97%
   duty factor,
since March 2004




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                    ALLEGRO Sensitivity

                                 Blue - 2003
                                 Red - 2004-now




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                                                  11
                    Global Network of
                     Interferometers
                         GEO      Virgo
 LIGO
                                                 TAMA




                                          AIGO
LIGO-G060291-00-Z
                                                        12
                    Status of interferometers
   The global network of 2006 – 2008 will center on LIGO,
     GEO, and Virgo.
      LIGO: 3 interferometers at 2 4 km sites
        (Hanford WA and Livingston LA)
      GEO: 600 m interferometer near Hannover
      Virgo: 3 km interferometer near Pisa
   TAMA 300 (Japan) has operated well, and is now
     undergoing upgrades.
   AIGO (Australia) is a lab for advanced interferometer
     technology, and (it is hoped) a site for a future large
     interferometer.

LIGO-G060291-00-Z
                                                               13
                                    LIGO
                      (here, LIGO Livingston Observatory)
A 4-km Michelson
interferometer,
with mirrors on
pendulum
suspensions.
Site at Hanford WA
has both 4-km and
2-km.
Scientific
operations began
Nov 2005, at design
sensitivity:
  LIGO-G060291-00-Z
hrms = 10-21.                                               14
             LIGO Hanford Observatory




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              LIGO Optical Configuration
   Power Recycled                    End Test Mass
  Michelson
  Interferometer                    4 km Fabry-Perot
  with Fabry-Perot                  arm cavity
  Arm Cavities

              Recycling
                                    Input Test
              mirror
                                    Mass
                            225 W                15000 W
           Laser
                     5W

                          signal        50/50 beam splitter

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                                                              16
                    LIGO Beam Tube




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                                     17
                    LIGO Vacuum Equipment




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                       Seismic Isolation
                    stack of
                    mass-
                    springs




LIGO-G060291-00-Z
                                           19
                    Mirror Suspensions

        10 kg Fused Silica, 25 cm diameter and 10 cm thick




                                                   magnet

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               LIGO sensitivity over time




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                         Recent noise budget,
                    Livingston 4 km interferometer




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                    GEO 600




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                              23
                      GEO600 optical layout


                                       600m




                                                         interferometer with
                                                            dual recycling


                        mode cleaner
          12W laser




                                              detector


LIGO-G060291-00-Z
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                    GEO all-silica pendulum




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                                      GEO Sensitivity
                                     in Science Runs
                                      Typical Sensitivity: Science Runs
                      -16
                 10
                                                                              S1 Aug 26 `02
                                                                              S3I Nov 5 `03
                 10
                      -17                                                     S3II Dec 31 `03
                                                                              S4 Feb 22 `05
                                                                              S5 N&W Mar 23 `06
                 10
                      -18                                                     S5 24/7 May '06
                                                                              GEO Design 550Hz
 ASD [h / Hz]




                      -19
                 10


                      -20
                 10


                      -21
                 10


                      -22
                 10


                      -23
                 10              2                                        3
LIGO-G060291-00-Z
                            10                                       10
                                                 Freq. [Hz]                                       26
                        GEO status
   • Within ~x3 of design sensitivity over wide band.
   • Now engaged in full-time observing.
   • Another commissioning period in late 2006 to reach
     design sensitivity.




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                                                          27
                                                                     EGO
                    •   LAPP - Annecy           •   ESPCI - Paris
                    •   INFN - Firenze/Urbino   •   LAL - Orsay
                    •   INFN - Frascati         •   INFN - Perugia
                    •   IPN - Lyon              •   INFN - Pisa
                    •   INFN - Napoli           •   INFN – Roma
                    •   OCA - Nice

                                       NIKHEF – Amsterdam (joining)


                        Inaugurated July 2003




LIGO-G060291-00-Z
                                                                       28
                      Virgo Optical Scheme

                    Input Mode Cleaner


                                              3 km long Fabry-Perot cavities:
                                              to lengthen the optical path to
                                              100 km


 Laser 20 W




                                                Output Mode Cleaner
                Power recycling mirror:
                to increase the light power
                to ~1 kW
LIGO-G060291-00-Z
                                                                                29
                         Virgo
                    Super-Attenuator




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                    Virgo commissioning started in 2003:
                    fast progress, approaching design sensitivity




        NS/NS maximum range  1.5 Mpc




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                                                                    31
                    Virgo status
   • Now in commissioning.
   • Expecting to be within ~x2 of design sensitivity by
     Fall 2006, then will commence observing.
   • Another commissioning period in first half of 2007 to
     reach design sensitivity.




LIGO-G060291-00-Z
                                                             32
                                  Observations with
                                 the Global Network

• Several km-scale
  detectors, bars now
  in operation
• Network gives:
   »   Detection
       confidence
   »   Sky coverage
   »   Duty cycle
   »   Direction by                                   AURIGA, Nautilus,
                                                      Explorer bars
       triangulation
   »   Waveform
       extraction
                       ALLEGRO
                       Baton Rouge LA
                       1 Bar detector




 LIGO-G060291-00-Z
                                                                          33
                         Plans for the
                        global network
   • GEO and LIGO carry out all observing and data
     analysis as one team, the LIGO Scientific
     Collaboration (LSC).
   • LSC and Virgo have almost concluded negotiations
     on joint operations and data analysis.
   • This collaboration will be open to other
     interferometers at the appropriate sensitivity levels.
     We will also carry out joint searches with the network
     of resonant detectors.




LIGO-G060291-00-Z
                                                              34
                          The S5 science run
   Now, that LIGO has reached design sensitivity, we are
     collecting data.
   Previous science runs had durations of only one or two
     months. Produced a number of upper limit papers.
   S5 is intended to collect one year of integrated
     coincident data at design sensitivity.
   S5 began in November 2005.
   Calendar duration depends on duty cycle.
         Duty cycle goal is ~70% for triple coincidence.
         So far, we have achieved about 45%.


   GEO has recently joined S5 full time, after
     commissioning and evening/weekend running.
LIGO-G060291-00-Z
                                                            35
                      Neutron star binary
                    inspiral range vs. date




LIGO-G060291-00-Z
                                              36
                    Coincidence fraction




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                                           37
                       Past burst upper limits,
                      bars and interferometers
Bars work
together as
IGEC. New                        IGEC 2
results are
expected soon.
LIGO 2003 burst
search
surpassed bars’
sensitivity, but
had short
observing time.
Sensitivity now
over x10 better,
integrating for
1 year.
  LIGO-G060291-00-Z
                                                  38
                     Untriggered Burst Search
No gravitational wave bursts detected during S1, S2, S3, and S4.
Upper limits set on burst rate and strength from S1, S2, and S4.
                                             Science Run 4

                                                                  Central
                      Detection Efficiency


                                                                 Frequency




                          hrss   h(t) dt
                                                             2


Rapid (high threshold) analysis of first few months of S5 has also not
yielded any detections of gravitational wave bursts.
 LIGO-G060291-00-Z
                                                                             39
                               Results from
                           S4 Stochastic Search
•   Weighted average of H1-L1 and H2-L1
    measurements:
      Ω  σΩ = (-0.8  4.3) × 10-5

•   Bayesian 90% UL:
     » Use S3 posterior distribution for S4
       prior.
     » Marginalized over calibration
       uncertainty with Gaussian prior (5%
       for L1, 8% for H1 and H2).

            Ω90% = 6.5 × 10-5




LIGO-G060291-00-Z
                                                  40
                               S5 upper limits on
                           signals from known pulsars
Closest to spin-down upper
limit:
Crab pulsar, only ~ 2.1 times
greater than spin-down

h0 = 3.0x10-24,
= 1.6x10-3
(fgw = 59.6 Hz, dist = 2.0 kpc)

We should have sensitivity below
spin-down limit on the Crab
pulsar before S5 is over.




   LIGO-G060291-00-Z
                                                        41
                                  Coming Soon:
                                 Advanced LIGO
Much better sensitivity:
• ~10x lower noise
• ~4x lower frequency
• tunable                                        Initial LIGO

Through these features:
• Fused silica multi-stage
suspension
• ~20x higher laser power
• Active seismic isolation
• Signal recycling
• Quantum engineering                        Advanced LIGO
 rad’n pressure vs. shot noise


    LIGO-G060291-00-Z
                                                                42
                              Reach of
                       advanced interferometers
Advanced LIGO and its
cousins (Advanced Virgo,
LCGT) are expected to
see lots of signals.
• Neutron star binaries
    »   Range =350Mpc
    »   N ~ 2/(yr) – 3/(day)
• Black hole binaries
                                       LIGO Range
    »   Range=1.7Gpc
    »   N ~ 1/(month) – 1/(hr)
• BH/NS binaries
    » Range=750Mpc
                                                             Image: R. Powell
    » N ~ 1/(yr) – 1/(day)

  LIGO-G060291-00-Z                    Advanced LIGO Range
                                                                          43
                    Status of Advanced LIGO
   PPARC is funding substantial U.K. contribution (£8M),
        including multi-stage fused silica test mass suspensions.

   Max Planck Society has endorsed major German
     contribution,
        with value comparable to U.K.’s contribution,
        including 200 W laser.



   U.S. National Science Board approved Advanced LIGO.
   We hope funds are included the next U.S. budget.



LIGO-G060291-00-Z
                                                                    44
                      Advanced LIGO
                      Seismic Isolation
3 stages of active seismic isolation,
plus 4 stages of passive isolation,
with fused silica pendulum suspension.




  LIGO-G060291-00-Z
                                          45
                        Other plans for the
                    Advanced Interferometer era
   • Advanced Virgo will be built on the same time scale
     as Advanced LIGO, and will achieve comparable
     sensitivity.
   • Japan’s Large Cryogenic Gravitational Telescope
     (LCGT) will pioneer cryogenics and underground
     installation.
   • GEO HF will improve the sensitivity beyond
     GEO 600’s, mainly at high frequency where shorter
     length is not an issue.
   • Resonant DUAL technology could equal or surpass
     that of interferometers at high frequencies.


LIGO-G060291-00-Z
                                                           46
                    The DUAL concept
                            The outer                     The inner
                            resonator is     π Phase      resonator is
Read the differential       driven above   difference     driven below
deformations of two         resonance                     frequency
 nested resonators


                                           3-5 kHz
                                           Intermediate
                                           GW broadband




                                   - gw signals add -
                            - back action noises subtract -


LIGO-G060291-00-Z
                                         Advanced detectors,
                                            next decade
h (Hz-1/2)
    h/ĆHz                                                                             2012-2018 Network
          -20                     Pulsars
     10
                LCGT-I h , 1 year integration
                        max
                                                               BH-BH Merger
                                                                Oscillations
                                                                @ 100 Mpc
          -21
     10
                                               QNM from BH Collisions,
                                                100 - 10 Msun, 150 Mpc
                                     BH-BH Inspiral, 100 Mpc
                                                                                           Core Collapse
          -22
     10                           QNM from BH Collisions,                                   @ 10 Mpc
                BH-BH Inspiral,    1000 - 100 Msun, z=1                -6
                    z = 0.4                                    NS, =10 , 10 kpc

                                                      NS-NS Inspiral, 300 Mpc
          -23
     10


                                     Advanced
     10
          -24
                                       Virgo                Advanced
                                                             LIGO
                                                                                3rd Generation ITF
          -25
     10
     LIGO-G060291-00-Z
                                                                                                                1048
                                                                                                                  4
                   10                               100                             1000                   Hz
                      Summary
   Gravitational wave detectors on the ground are now
     operating full-time at unprecedented sensitivity.

   Detection of gravitational waves by ground based
     detectors is expected, if not from this generation,
     then from its successors that will start construction
     within a few years.




LIGO-G060291-00-Z
                                                             49

								
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