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ET – THE Einstein telescope INSTRUMENTAL ASPECTS

ET – THE Einstein telescope INSTRUMENTAL ASPECTS. Harald Lück AEI Hannover. The goal. ETb. 10 -19 10 -20 10 -21 10 -22 10 -23 10 -24 10 -25. LIGO. Virgo. Strain [1/(Hz) 1/2 ]. ETc. Advanced LIGO/Virgo . 1 10 10 2 10 3 10 4. Frequency (Hz). You are here. You are here.

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ET – THE Einstein telescope INSTRUMENTAL ASPECTS

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  1. ET–THE Einstein telescopeINSTRUMENTAL ASPECTS Harald Lück AEI Hannover

  2. The goal ETb 10-19 10-20 10-21 10-22 10-23 10-24 10-25 LIGO Virgo Strain [1/(Hz)1/2] ETc Advanced LIGO/Virgo 1 10 102103 104 Frequency (Hz)

  3. You are here You are here A long road Routine Observation Detection Phase Rare Observation Virgo+ Advanced Virgo GEO 600 Hanford Advanced LIGO E-LIGO Livingston Launch Transfer Site Prep. data PCP DS Construction Comm. 3rd Gen. 1st Generation 2nd Generation GW Detection is a prerequisite for building ET

  4. The GWIC roadmap

  5. The Einstein Telescope • The Einstein Telescope project is currently in its conceptual design study phase, supported by the European Union within FP7 with about 3M€ from May 2008 to July 2011. Einstein Telescope Science team total: 249

  6. Basic assumptions: ET will be a long lasting (decades) infrastructure Only mature techniques are foreseen as baseline design Subsequent upgrades to novel techniques will follow ET will be built underground, (see ‘seismic slides’) Overall tunnel length will be 30km ET will be built in a ‘triple Michelson’ arrangement (CQG 26 085012, 2009) Techniques for ET

  7. Antenna pattern doi: 10.1088/0264-9381/26/8/085012

  8. 2nd Generation design sensitivity We consider: Michelson topology with dual recycling. One detector covering the full frequency band A single detector (no network) Start from a 2nd Generation instrument. Each fundamental noise at least for some frequencies above the ET target. => OUR TASK: All fundamental noises have to be improved !! Starting point: 2ndGeneration 3G target sensitivity (approximated) Courtesy:StefanHild

  9. Increasing the arm length DRIVER: All displacement noises ADV (3km) ACTION: Increasearm length from 3km to 10km EFFECT: Decrease all displacement noises by a factor 3.3 ET (10km) Courtesy:Stefan Hild

  10. Gravity Gradient Noise Credit: M.Beker, Nikhef

  11. Credit: M.Beker, Nikhef

  12. Seismic measurements Credit: M.Beker, Nikhef

  13. Seismic measurements Credit: M.Beker, Nikhef

  14. Seismic measurements Credit: M.Beker, Nikhef

  15. Seismic measurements Credit: M.Beker, Nikhef

  16. Signal Recycling DRIVER: Quantum noise ACTION: From detuned SR to tuned SR (with 10% transmittance)

  17. More laser power DRIVER: Shot noise at high frequencies ACTION: Increase laser power (@ ifo input) from 125W to 500W EFFECT: Reduced shot noise by a factor of 2 Courtesy:Stefan Hild

  18. DRIVER: Shot noise at high frequencies Quantum noise REduction ACTION: Introduced 10dB of squeezing (frequency depend angle) EFFECT: Decreases the shot noise by a factor 3 Detuned Squeezing requires filter cavities Courtesy:Stefan Hild

  19. Filter Cavities • The effective squeezing level of lossy filter cavities for the low and high frequency ET Xylophone

  20. Filter Cavities [paper in preparation]

  21. Detector topologies different than Michelson might offer even better quantum noise reduction, i.e. Dual Recycled Sagnac with arm cavities or Optical Bar / Optical Lever topologies. QND TechniquesNot foreseen for Initial Topology Speedmeter sensitivity. H. Mueller-Ebhardt et al: https://pub3.ego-gw.it/itf/tds/file.php?callFile=ET-010-09.pdf

  22. DRIVER: Coating Brownian noise Increasing the beam size ACTION: Increase of beam radius from 6 to 12cm EFFECT: Decrease of Coating Brownian by a factor 2 OR: Courtesy:StefanHild

  23. Si 500 nm Waveguides may provide an elegant way to reduce coating Brownian noise. Idea: replacingthedielectric(lossy, thick) multi-layerstackby a (lowloss, thin) mono-crystallinesilicon nano-structureor a (thin) singlelayerdiffractivecoating. Brückner et al., Optics Express 17 (2009) 163 – 169 Waveguide Coatingsreducing Mechnical dissipation Brückner et al., Optics Letters 33 (2008) 264 - 266 OR:

  24. “Khalili” cavities (F.KhaliliPhysics Letters A, 2005, 334, 67 - 72) allow to reduce the influence of coating Brownian noise. No Khalili End mirror (Khalili) cavities With Khalili • Using Khalili-cavities as end mirrors, we can reduce the total mirror thermal noise of the whole interferometer by about a factor 1.5.

  25. Cooling the test masses DRIVER: Coating Brownian noise CLIO + LGCT ACTION: Reduce the test mass temperature from 290K to 20K EFFECT: Decrease Brownian by ~ factor of 4 Kuroda 2008 LIGO-G080060 Requires “cryogenic material” ->silicon Courtesy:StefanHild

  26. Silicon • Fused Silica unusable at cryo-temperatures • Sapphire and Silicon best candidates • Sapphire selected in LCGT • Silicon under study in ET Jena Group 2009 McGuigan 1978 Silicon loss angle • Floating zone • high purity, up to 30 kOhms cm • < 200mm diameter • Czochralski • more impurities, <300 Ohms cm • >300mm? ; bigger sizes in the ET era ? 10-8 1.5mm

  27. Suspensions DRIVER: Seismic noise S.Brachini: http://gw.icrr.u-tokyo.ac.jp/gwadw2010/program/2010_GWADW_Braccini.ppt ACTION: Build a 17m Virgo-Style Superattenuator EFFECT: Decrease seismic noise by many orders of magnitude or pushes the seismic wall from 10 Hz to about 1.5 Hz Courtesy:StefanHild

  28. Suspension Towers

  29. ‘Xylophone’: cool & hot 20K300K • For more details please see • S.Hild, S.Chelkowski, A.Freise, J.Franc, R.Flaminio, N.Morgado and R.DeSalvo: ‘A Xylophone Configuration for a third Generation Gravitational Wave Detector’, CQG 2010, 27, 015003

  30. For efficiency reasons build a triangle. Start with a single xylophone detector. installation of ET

  31. installation of ET For efficiency reasons build a triangle. Start with a single xylophone detector. Add second Xylophone detector to fully resolve polarisation.

  32. installation of ET For efficiency reasons build a triangle. Start with a single xylophone detector. Add second Xylophone detector to fully resolve polarisation. Add third Xylophone detector for redundancy and null-streams.

  33. Status and future of GW observatories • 1stgeneration successfully completed: • Long duration observations (~1yr) in coincidence mode of 5 oberservatories. • Beat Spin-down upper limit of the Crab-Pulsar • 2ndgeneration on the way: • End of design phase, construction started • 10 times better sensitivity than 1st generation. => Scanning 1000 times larger volume of the Universe • 3rdgeneration at the horizon: • FP7 funded design study in Europe • 100 times better sensitivity than 1st generation. => Scanning 1000000 times larger volume of the Universe LCGT

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