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VIRGO LAPP – Annecy NIKHEF – Amsterdam INFN – Firenze-Urbino INFN – Frascati IPN – Lyon INFN – Napoli OCA – Nice LAL – Orsay ESPCI – Paris INFN – Perugia.

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Presentation on theme: "VIRGO LAPP – Annecy NIKHEF – Amsterdam INFN – Firenze-Urbino INFN – Frascati IPN – Lyon INFN – Napoli OCA – Nice LAL – Orsay ESPCI – Paris INFN – Perugia."— Presentation transcript:

1 VIRGO LAPP – Annecy NIKHEF – Amsterdam INFN – Firenze-Urbino INFN – Frascati IPN – Lyon INFN – Napoli OCA – Nice LAL – Orsay ESPCI – Paris INFN – Perugia INFN – Pisa INFN – Roma Status of the VIRGO Interferometer S.Braccini – INFN Pisa

2 Part 1 – Introduction Part 2 – Design Part 3 – Commissioning Part 4 – Future

3 VIRGO is a typical interferometric GW detector  L    m h   (VIRGO Supernova) L    m

4 VIRGO is a typical interferometric GW detector h = 10 -21   gw  = 3·10 -11 rad

5 Fabry-Perot cavities to increase the effect Increase beam phase shift by 2F 

6 Optical Readout Noise 20 W  1 kW An accurate measurement of the phase requires a large amount of photons…

7 Fluctuation-dissipation theorem Thermal Noise Reduce dissipations in the optical payloads to reduce thermal fluctuations

8 Seismic Noise Suspend each mirror by a cascade of 6 dof oscillators frequency transmission Ground Seismic Vibrations

9 Summary of the technique Low Dissipations Fabry-Perot photodiode Recycling High Power Laser Seismic Isolation

10 Part 2 – VIRGO Design

11 VIRGO Optical Layout 20 W Laser Input Mode Cleaner (144 m) Output Mode Cleaner (4 cm) Power Recycling Fabry-Perot Cavities (3 km)

12 VIRGO design sensitivity curve Thermal Shot Seismic

13 Injection System A few Hz frequency rms stability is achieved in the input beam

14 Superattenuators Blade springs Magnetic antisprings Extend the band down to a few Hz 6 m

15 Mirror Ground Displacement (m/Hz 1/2 ) Frequency (Hz) Seismic Isolation Thermal Noise Measured Upper Limit

16 Pitch Yaw Coil-Magnet Actuators Mirror Local Controls Tens of  rad Fractions of  rad Optical Lever

17 Resonance Crossing   Mirror Optical Surface MIRROR SWING Photodiode demodulated signal during resonance crossing HOOK CAVITIES AT RESONANCE USING MIRROR COIL-MAGNET ACTUATORS (Picometer Accuracy) Interferometer Locking

18 Coils Marionetta Mirror Reference Mass Beam Suspension Last Stage Reference Mass Mirror Beam Coils Marionetta

19 Mirror Ground Displacement (m/Hz 1/2 ) Frequency (Hz) Thermal Noise Seismic Isolation Low Frequency Swing

20 Fixed Stars ADC DSPDAC Accelerometers Coil-Magnet Actuators Inertial Damping

21 Fixed Stars Inertial Damping Mirror Optical Surface Mirror swing reduced from several  m/s to a fraction of  m/s Enough to allow locking acquisition

22 Summary Seismic Noise Suppression above 4 Hz Damp angular swings by local controls (10 -7 rad) to allow a good interference Reduce longitudinal swing by Inertial Damping (0.5  m/s) to allow locking Mirror Optical Surface Pre-Stabilized Beam Source (a few Hz)

23 Part 3 - Commissioning

24 RECYCLING CAVITY = l 0 + (l 1 + l 2 )/2 4 degrees of freedom to be controlled (“locked”) l2l2 l1l1 MICHELSON = l 1 - l 2 COMMON ARM LENGTH = L 1 + L 2 L2L2 L1L1 DIFFERENTIAL ARM LENGTH = L 1 - L 2 l0l0 Interferometer Locking

25 l2l2 l1l1 L1L1 L2L2 l0l0 Variable Finesse Locking Acquisition

26 L1L1 L2L2 l2l2 l1l1 l0l0 Low Finesse of Recycling Cavity Arm cavity fields do not mix Dark Port DC signal Variable Finesse Locking Acquisition PR Mirror rotated by 100 microrad 50 % Interference (Gray Fringe) Easy preliminary locking (mirror swing is stopped)

27 Pick-off Laser Frequency follows CARM motion L1L1 L2L2 l2l2 l1l1 l0l0 Dark Port DC signal Variable Finesse Locking Acquisition Put in action the “Second Stage Frequency Stabilization Loop” Common Arm motion is controlled by laser with high accuracy

28 L1L1 L2L2 l2l2 l1l1 l0l0 Dark Port DC signal Variable Finesse Locking Acquisition Pick-off Laser Frequency follows CARM motion Slow Alignment of the Recycling Mirror

29 L1L1 L2L2 l2l2 l1l1 l0l0 Dark Port DC signal Variable Finesse Locking Acquisition Slow Alignment of the Recycling Mirror Pick-off Laser Frequency follows CARM motion

30 L1L1 L2L2 l2l2 l1l1 l0l0 Dark Port DC signal Variable Finesse Locking Acquisition Slide to Dark Fringe

31 DC-0.01 Hz Tide control 0.01-5 Hz 5-50 Hz Hierarchical Control millimiters fractions of micron nm Actuators engender a noise floor proportional to the amplitude of their force range Only nm displacements can be compensated at the mirror level

32 Use Quadrant Photodiodes to Close Automatic Alignment After Locking…. 10 -7  10 -9 rad

33 Single arm Recombined Recycled VIRGO run sensitivities

34 LIGO and VIRGO

35 Duty Cycle (%) Time (days) Duty Cycle during C6 run

36 VIRGO Horizon Horizon NS/NS – Optimal Incidence 1 day

37 Measure the sensitivity  Identify the noise sources  Try to reduce the noise C6 Improvements Automatic Alignment New Filter for Recycling Control Subtraction of Beam Splitter Control Noise Reduction of laser frequency noise 2kHz bump due to detection tower pump (exciting external bench) Less dynamics for BS correction Noise Hunting

38 Control Noise Photodiode Noise C7 Run Noise Budget

39 Incident Beam 12 cm Translations induce beam jitters Recycling Transfer Function The problem of power recycling mirror 350 mm

40 New monolithic flat power recycling mirror Recycling Transfer Function Old New

41 Laser Frequency Noise (After Mode Cleaner) Power Recycling Mirror Misaligned Power Recycling Mirror Aligned Suppress back-scattered light Hz Time Faraday Isolator on Input Bench Up to now VIRGO operated with a reduced power (from 7 W down to 700 mW)  Limited Sensitivity in High Frequency Range The problem of back-scattered light

42 New injection bench

43 Interferometer locked Interferometer now in action with 7 W input power Faraday isolation ~ 100 (nominally much larger but enough) New Injection Bench Performance Mode Cleaner Transmission signal (Now) Mode Cleaner trasmission signal (Before)

44 Reduction of sidebands power by a factor ~ 4 (time constants ~ a few minutes) A New Problem - The thermal effect 10 min CARRIER POWER SIDEBAND POWER

45 A New Problem - The thermal effect Lock is kept for long periods despite of this problem 10 hours SIDEBAND POWER CARRIER POWER 15 min SIDEBAND POWER CARRIER POWER

46 The Present Status * Interferometer locked for a long period with 7 W input power * 10 dof of automatic alignment controlled * Sensitivity curve measured and noise hunting restarted Just a “technical sensitivity” curve to show that itf restarted C7 Now

47 Part 4 – The Future

48 2006: Noise reduction  Reach design sensitivity above 100 Hz 2007: Scientific Run (stop for upgradings ?) 2008: VIRGO+ assembly and commissioning NETWORK AGREEMENT AND JOINT ANALYSIS Plans for next years

49 Thermal Shot Seismic 50 W laser Monolithic Suspensions VIRGO + Improvements

50 VIRGO + Design Sensitivity VIRGO + VIRGO DESIGN

51 First Generation Sensitivity 10 -24 10 -23 10 -22 10 -21 10 -20 10 -19 10 -18 110100100010 4 VIRGO LIGO Resonant Antennas 2007 Hz GEO Core Collapse @ 10 Mpc BH-BH Merger Oscillations @ 100 Mpc Pulsars h max, 1 year integration BH-BH Inspiral, z = 0.4 BH-BH Inspiral, 100 Mpc QNM from BH Collisions, 1000 - 100 Msun, z=1 NS,  =10 -6, 10 kpc QNM from BH Collisions, 100 - 10 Msun, 150 Mpc NS-NS Inspiral, 300 Mpc NS-NS Merger Oscillations @ 100 Mpc Unlikely Detection

52 h 10 -24 10 -23 10 -22 10 -21 10 -20 10 -19 10100100010 4 Hz Core Collapse @ 10 Mpc NS-NS Merger Oscillations @ 100 Mpc BH-BH Merger Oscillations @ 100 Mpc Pulsars max, 1 year integration BH-BH Inspiral, z = 0.4 BH-BH Inspiral, 100 Mpc QNM from BH Collisions, 1000 - 100 Msun, z=1 NS,  =10 -6, 10 kpc QNM from BH Collisions, 100 - 10 Msun, 150 Mpc NS-NS Inspiral, 300 Mpc VIRGO + SFERA (Canceled) DUAL Demonstrator (2011) LIGO+ Likely Detection Upgraded Network (2008-2012) h GEO-HF (2009/10)

53 Next Generation Advanced Virgo (2012) Design activity still not started R&D activities on High power lasers Signal recycling and optical topologies Coatings Electrostatic actuators

54 Part 4 - Future Advanced Virgo White Paper VIR – NOT – DIR – 1390 – 304 Beyond 2012

55 10 -25 10 -24 10 -23 10 -22 10 -21 10 -20 10100100010 4 Advanced Virgo Hz Core Collapse @ 10 Mpc NS-NS Merger Oscillations @ 100 Mpc BH-BH Merger Oscillations @ 100 Mpc SFERA QND Pulsars h max, 1 year integration LCGT-I 3rd Generation ITF BH-BH Inspiral, z = 0.4 BH-BH Inspiral, 100 Mpc QNM from BH Collisions, 1000 - 100 Msun, z=1 NS,  =10 -6, 10 kpc QNM from BH Collisions, 100 - 10 Msun, 150 Mpc Advanced LIGO NS-NS Inspiral, 300 Mpc DUAL SiC SFERA QL Detection is “sure” Beyond 2012

56 NS/NS detectable @ hundreds of Mpc ITF+ 2009 Advanced VIRGO-LIGO 2013 VIRGO-LIGO 2006 Virgo

57 Now: VIRGO is again in action with 7 W input beam Conclusions 2006: End of commissioning 2007: Scientific Run with a sensitivity comparable to LIGO Open Problems: Thermal compensation, Low frequency control noise 1st GENERATION NETWORK IS IN ACTION ! …. VIRGO+ (2009) and VIRGO Advanced (2012-13)

58 The End

59 MATRIX Old injection system autoalignment layout Ref. cav. MC mirror Laser M5 M6 Ref. cav. autoalignment MATRIX Injection bench MC mirror autoalignment -- Inj.B. local control -- Beam autoalignment -- IB Coils MC AA Picomotors Piezos Wavefront sensors

60 MATRIX New injection system autoalignment layout Ref. cav. MC mirror Laser M5 M6 MATRIX RFC AA Beam prealignment MATRIX MC IB AA IB Coils Ref.cav. autoalignment Picomotors Piezos -- Injection bench MC mirror autoalignment -- Inj.B. autoalignment -- Beam autoalignment -- DC position sensors Wavefront sensors

61 1. Mirror excitation in windy conditions –=> more frequent unlocks when weather is bad 2. DAC noise on mirror actuation coils –High force needed for lock acquisition –=> bad DAC dynamics in steady conditions (low force) Micro-seismic peak (sea waves) Suspension: recent problems seismic acceleration wind speed susp displacement noisy day calm day

62 Suspension: inertial damping modification L(s) H(s) L+H = 1 accelerometer LVDT Inertial damping –Inverted pendulum top platform is immobilized by –HF accelerometers (inertial sensors) –LF LVDT’s (ground based) => introduce seismic noise Solution –Reduced HF/LF cross-over frequency to 30 mHz –Not so simple... (see G. Losurdo’s talk) LVDT = linear variable differential transformer 30 mHz

63 Thermal effects 10 min  Reduction of sidebands power by a factor ~4  Time constants ~ a few minutes  Power reduction planned at the beginning of June  Study of the effect by simulation and experimental measurements (scanning Fabry-Perot)

64 LIGO-Virgo Run Planning The agreement foresee also a run coordination – “A Joint Run Planning Committee will be formed, consisting of the Virgo and LSC Data Analysis Coordinators, plus relevant experts from Virgo, GEO, and LIGO on topics such as: calibration, detector characterization/vetoes, detector planning, commissioning, and site management…” Start sketching a possible joint run planning VERY PRELIMINARY

65 Part 3 VIRGO Future

66 CERN – C.A.P.P. workshop – June 16 th, 2003 G.Losurdo – INFN Firenze-Urbino Sensitivity improvement The nominal Virgo sensitivity is dominated by –the shot noise, at high frequency –the pendulum thermal noise at low frequency

67 VIRGO intende raggiungerla nei prossimi mesi


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