LIGO Status Report 1. LIGO I. 2. E7 run (Dec.28,2001 ~ Jan.14,2002) 3. Advanced LIGO. Hiro Yamamoto

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1 LIGO Status Report Hiro Yamamoto LIGO Laboratory / California Institute of Technology 1. LIGO I 2. E7 run (Dec.28,2001 ~ Jan.14,2002) 3. Advanced LIGO References : M.Coles (G020009), D.Coyne and D.Shoemaker (G010237), Z. Marka (LIGO seminar 2/1/02), F.Raab (G020012), D.Ugolini(LIGO seminar 2/8/02), A.J.Weinstein(G020007) 1

2 LIGO I Detector Being Commissioned Major hardware construction completed Completion of the remaining hardware and software Commissioning of detectors Diligent tuning and noise hunting Engineering run aiming to improve hardware performance (for LIGO Lab) Scientific run for the (preparation of ) physics research (for LSC) LIGO run starts next year 2

3 LIGO I Lock status LHO 2k» 6W, WFS, Common mode servo» ~20 minutes lock» Studying to understand the higher power effect LHO 4k» 1W, Digital Suspension Controller» ~ a few minutes lock (max of 36 minutes)» Seeking to achieve stable lock, improving digital suspension controller (LLO waiting for this result) LLO» 1W» ~ several minutes lock (max of several hours) at night Cultural noise too high in the daytime, and train passing over bridge breaks lock» Seeking for better seismic isolation External pre-isolation : Hydraulic, EM or Piezo actuators Internal active dumping 3

4 Logging at Livingston Less than 3 km away Dragging big logs Remedial measures at LIGO are in progress; this will not be a problem in the future. 4

5 Reduction by feed-forward from seismometers 5

6 6 Analysis of feedback gives nonmodeled tidal and temperature effects 11/09/00 11/10/00 11/11/00 11/12/00 11/13/00 11/14/00 11/15/ µ / Hr 0 Feed-back removes ~20% 20 Differential mode with model 40 Simple model in feed-forward removes ~80% E2 data Prediction 11/09/00 11/10/00 11/11/00 11/12/00 11/13/00 11/14/00 11/15/ Actuation in end/mid- stations and on laser reference cavity µ / Hr Common mode with model Largest Source of Interferometer Drift Earth Tide

7 Continued improvement in PSL Frequency Noise Simplification of beam path external to vacuum system Acoustic and seismic isolation Broadband noise better than spec in Hz region 7

8 Strain Sensitivity of LIGO IFO s during E7 (very preliminary!!) Contributions: PSL frequency noise (need common mode servo on all IFOs) Misalignments (reduce noise in oplevs; tuning of alignments servos needed) Laser glitches & bursts (reduce acoustic coupling into PSL) Periscope vibrations on PSL table (~200 Hz) Photodetector preamp Johnson noise (high-f) Excess noise in Pentek ADCs Excess coil driver/dac noise Unidentified electronics noise Low laser power (operating at 1 watt, not 6 watts) 8

9 Progress since E7 Common-mode feedback from arms to laser frequency is now engaged on Hanford 2-km interferometer» Improved control of laser frequency noise» Establishes gain hierarchy to get better-conditioned control system Power-recycling works on Hanford 4-km interferometer» Important validation of digital suspension controllers Laser power increased to 6 W for Hanford 2-km interferometer; tuning up under new operating conditions Improved locking of Livingston 4-km interferometer 9

10 Hanford 2km interferometer improvements after E7 Closed feedback loop from arms to laser frequency Reallocation of gains within length control servo system laser power 1 W 10

11 Future works Electronic noise hunting» 1/f 3 ~ 1/f (electronic noise) x 1/f 2 (pendulum)» 60 Hz and higher harmonics» Laser power stabilization Optical shutter control» attenuation loss ~ 1/8 WFS Better seismic isolation system, espacially at LLO All interferometers still need many control loops to be closed and then tuned 11

12 E1 E2 E3 E4 E5 E6 E7 S1 12 S1 April November 2001 March May August October hours ~June? ALLEGRO A cryogenic bar detector GEO-600, Power recycled LLO 4km, Recombined LHO 4km, Recombined LHO 2km, Power recycled 4 interferometric detectors LIGO GEO ALLEGRO Coordination among Engineering Run 7 (E7) International Network of Gravity Wave Detectors

13 E7 : 28Dec01 14Jan02 Engineering runs test partially integrated and commissioned machines under operational conditions to identify needed improvements E7 was first engineering run to include all 3 interferometers in coincidence and tested on-line data analysis at Hanford and Livingston E7 data sets will be analyzed jointly with data sets from GEO600 and Allegro E7 analysis will exercise full range of astrophysical data-analysis software 13

14 E7 : Interferometer Configurations Hanford 4-km : 1W recombined» digital suspension controllers» tidal compensation Hanford 2-km : 1W full power-recycling» differential-mode wave-front control» analog suspension controllers» tidal compensation Livingston 4-km : 1W recombined» analog suspension controllers» microseism compensation 14

15 E7 : Analysis Working Groups Data from E7 is being analyzed by LSC working groups for:» Detector Characterization» Binary Inspirals» Bursts» Periodic Sources» Stochastic Background This exercise will test analysis methodology for 1 st Science Run S1 this summer and feed back results into detector commissioning and code-writing effort 15

16 E7: LIGO IFO duty cycle Locked segments (minutes) Integrated lock hours (all segments) Integrated lock hours (15 min or longer segments) 380 hrs LLO 4k LHO 4k LHO 2k 3 IFO LHO LLO 4k total time (hrs) duty cycle (%) lock > 15 minutes time (hrs) duty cycle (%)

17 Magnitude [au] E7: monitor example Violin mode decays as seen at DARM_CTRL» +/- 5Hz band around 345 Hz Excellent info for operators 17 Plot courtesy of J. Zweizig

18 GPS time (S), T = 0.062s Frequency (Hz), f = 16 Hz /1.4 Solar Mass NS/NS Inspiral signal in AS_Q... (Lormand, Adhikari) signal injections E7: 18

19 E7 : Run summary 19

20 Advanced LIGO Advanced LIGO» Seismic noise Hz» Thermal noise 1/15» Shot noise 1/10, tunable» Reasonable / exciting extrapolations of technical developments Facility limits» Gravity gradients» Residual gas» (scattered light) Plan» Single step significant upgrade» Initial LIGO observations until 2006~7, then change to Advanced LIGO» One IFO at a time to keep the international network functional 20

21 Nominal top level parameters Sapphire Fused Silica Fabry-Perot arm length 4000 m Laser wavelength 1064 nm Optical power at interferometer input 125 W 80 W Power recycling factor FP Input mirror transmission 0.5% 0.50% Arm cavity power 830 kw 530 kw Power on beamsplitter 2.1 kw 1.35 kw Signal recycling mirror transmission 6.0% 6.0% Signal recycling mirror tuning phase 0.12 rad 0.09 rad Test Mass mass 40 kg 30 kg Test Mass diameter 32 cm 35 cm Beam radius on test masses 6 cm 6 cm Neutron star binary inspiral range (Bench) 300 Mpc 250 Mpc Stochastic GW sensitivity (Bench units) 8 x x

22 Interferometer overview MC : Silica 2.9kg / 15cm / 7.5cm Triple + silica or metal fibers ETM, ITM : Sapphia 40kg / 31.4cm / 13cm quad + silica ribbon ~16m BS : silica HERAEUS SV 12.7kg / 35cm / 6cm quad + silica fiber? CS : Compensator Same quality as BS CS PRM/SRM : silica LIGO I quality 12.1kg / 26.5cm / 10cm triple+silica or metal fibers? T=7% ~1m 22

23 Core Optics Material Development Sapphire Why Sapphire?» Sapphire has higher Q» Thermal conductivity is 30 x higher» Rayleigh scattering is ~ 30x lower Sapphire vs Silica : Dec Crystal Systems, Inc, Shanghai Institute for Optics and Fine Mechanics(SIOM) Large sapphire» 40kg, 31.5cm x 13cm High quality» Homogeneity < 10nm rms / single path measurement : 5-10 times worse» Absorption < 10ppm/cm measurement : 40-50ppm/cm 100mmx50mm a-axis sapphire 23

24 Sapphire Polishing Demonstration of super polish of sapphire (150mm diameter, m-axis) Radius of Curvature» Requirement: ROC 50 km +/- 10 km, OR sagitta of 52 nm +/- 10 nm» Achieved: 47 nm sagitta Surface Error» Requirement: <0.8 nm rms over the central 120mm <0.4 nm rms over the central 80mm» Achieved: 1 nm rms over the central 120mm 0.6 nm rms over the central 80mm probably limited by metrology will be measured by Caltech Microroughness» Goal <0.1nm rms; Requirement <0.2 nm rms» The average microroughness over the surface was 0.18 nm rms (though due to measurement noise expected to be actually 0.12 nm rms) 24

25 Optics Coating Research Virgo-SMA(Lyon, France), MLD(Oregon), REO(Boulder)??? Research mechanical loss, absorption, birefringence Different materials (Ta 2 O 5,Nb 2 O 5,ZrO 2,Al 2 O 5 ), combination of thicknesses, annealing temperatures Absorption : some of the coating satisfies the requirement, 0.2ppm. Loss : We have unambiguous information that the coatings are lossy with a φ around 1-3x10-4, and a program to identify the nature of the problem which is starting to yield results that suggest it is a bulk rather than an interface problem. 25

26 Optical homogeneity Need 5 to 10 x reduction of inhomogeneity Computer controlled spot polish by Goodrich (formerly HDOS)» Achieved 14 nm rms single path» has done compensating polish on a-axis sapphire» will spot polish the 25 cm dia.piece» expect to compensate for frequencies up to.08/mm or ~ 12mm/cycle Ion beam etching, fluid stream polish, compensating coating by CSIRO» Have experience in ion beam etching and compensating coating» Difficulty is high spatial frequency for correction Investigate a-axis and m-axis homogeneity (as alternative to c- axis) 26

27 Advanced Interferometer Sensing & Control (ISC) Use two SB (9MHz,180MHz) to sense 5 lengths Shift to DC readout» Rather than RF mod/demod scheme, shift interferometer slightly away from dark fringe; relaxes laser requirements, needs photodiode develop Requires both proof-of-principle and precision testing (GEO Glasgow 10m, Caltech 40m) LIGO Lab leads, with contributions from LSC, esp. GEO 27

28 New view of 40m Lab RSE controls/engineering prototype N E E S 12m suspended mode cleaner Output optics chamber Expect to exercise mode cleaner in summer 2002 and full IFO in summer

29 Quad pendulum prototype - GEO suspension Adopting a multiple-pendulum approach» Allows best thermal noise performance of suspension and test mass; replacement of steel suspension wires with fused silica» Offers seismic isolation, hierarchy of position and angle actuation 29

30 Active Seismic Isolation render seismic noise a negligible limitation to GW searches» Choose to require a 10 Hz brick wall reduce or eliminate actuation on test masses» Choose to require RMS of <10-11 m Conceptual Design Two in-vacuum stages in series, external slow correction Each stage carries sensors and actuators for 6 DOF Stage resonances ~5 Hz High-gain servos bring motion to sensor limit in GW band, reach RMS requirement at low frequencies Similar designs for BSC, HAM vacuum chambers; provides optical table for flexibility 30

31 LIGO Advanced System Test Interferometer (LASTI) at MIT Full-scale tests of Seismic Isolation and Test Mass Suspension. Allows system testing, interfaces, installation practice. Characterization of nonstationary noise, thermal noise. HAM HAM BSC HAM 31

32 Advanced R&D: Optics Thermal Compensation Thermoelastic deformation Thermal lens Extend LIGO I WFS to spatially resolve phase/ OPD errors Thermal actuation on core optics 100 nm Bump On HR surface In Input Test Mass 100 nm lens for Sapphia 1000 nm lens for Silika 10 nm lens In Beam Splitter 32

33 Adv. LIGO PSL Evaluate high-power-stage concepts» MOPA slab (Stanford) uses proven technology but expensive due to the large number of pump diodes required» stable-unstable slab oscillator (Adelaide) typically the approach adopted for high power lasers, but not much experience with highly stabilized laser systems» rod systems (Hannover) uses proven technology but might suffer from thermal management problems» High power design selection : LSC meeting this fall Power and frequency stabilization» Max-Planck Institute, University of Glasgow, University of Hannover Challenge» Intensity stabilization 3 x 10Hz 33