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Design study for 3rd generation interferometers Work Package 1 Site Identification

Design study for 3rd generation interferometers Work Package 1 Site Identification. Jo van den Brand e-mail: jo@nikhef.nl. Third generation detector. Two order of magnitude compared to initial Virgo Underground site Multiple interferometers: 3 Interferometers; triangular configuration?

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Design study for 3rd generation interferometers Work Package 1 Site Identification

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  1. Design study for 3rd generation interferometersWork Package 1Site Identification Jo van den Brand e-mail: jo@nikhef.nl

  2. Third generation detector • Two order of magnitude compared to initial Virgo • Underground site • Multiple interferometers: • 3 Interferometers; triangular configuration? • 10 km long • 2 polarization + redundancy • Design study part of ILIAS & FP7 • Construction: 2010-16 ? Rüdiger, ‘85

  3. Production: fundamental physics in the early universe- Inflation, phase transitions, topological defects- String-inspired cosmology, brane-world scenarios Spectrum slope, peaks give masses of key particles & energies of transitions A TeV phase transition would have left radiation in 3G band Scientific justification for 3rd generation ITF Primordial gravitational waves

  4. Introduction • Features of 3rd generation ITF • Sensitivity below 10-24 m/sqrt(Hz) • Ultra-low frequency cut-off • Vibration isolation • Sensitive in range 0.1 – 10 Hz • Multiple sites for signal correlation • Advanced optical schemes (squeezed light) • Cryogenic optics • Underground sites • 10 kilometer arms

  5. 1st - 2nd generation 10 Hz cutoff Ultra Low Frequency: 1Hz 3rd generation 1 Hz cutoff One more decade at low frequency

  6. Isolation requirements Required isolation @1 Hz: at least 1010 with ground noise. • Ultra soft vibration isolation • Long pendulums (50, 100 m) • Very good thermal stabilization • Active platforms • Very low noise sensors • Very good thermal stabilization • Very low tilt noise • Very quiet site

  7. Site identification process V. N. Rudenko, A. V. Serdobolski, K. Tsubono, “Atmospheric gravity perturbations measured by a ground-based interferometer with suspended mirrors”, Class. And Quant. Grav., vol. 20, pp. 317-329. Even pressure fluctuations due to weather are a relevant source of gravity gradient noise [11]. Seismic measurements at LNGS

  8. LIGO Site selection criteria

  9. LIGO Site evaluation criteria

  10. LIGO Site evaluation criteria

  11. Seismic noise attenuation

  12. Not only seismic noise… • Direct action of wind on buildings • Strong correlation between mirror motion and wind speed at f < 0.1 Hz • Detector operation more difficult in windy days, duty cycle affected • Even more difficult in the future, with high finesse cavities

  13. Underground interferometers • LISM: 20 m Fabry-Perot interferometer, R&D for LCGT, moved from Mitaka (ground based) to Kamioka (underground) • Seismic noise much lower: • 102 overall gain • 103at 4 Hz

  14. Interferometer operation becomes much easier underground. Noise reduced by orders of magnitude S.Kawamura, ‘02 LISM at Mitaka LISM at Kamioka limit by isolation system Displacement spectrum m/RHz Hz

  15. Large-scale Cryogenic Gravitational-wave Telescope: LCGT

  16. CLIO – Prototype for LCGT

  17. LISM in Kamioka

  18. ILC, NLC, Tesla, VLHC, Muon Source – Site requirements

  19. ILC, NLC, Tesla, VLHC, Muon Source – Site requirements

  20. Newtonian noise SEISMIC NOISE Isolation shortcircuit Figure: M.Lorenzini

  21. Seismically generated Newtonian noise

  22. Newtonian noise estimate Cella-Cuoco, 98

  23. NN reduction Courtesy: G.Cella • Surface waves give the main contribution to newtonian noise • Surface movement dominates the bulk compression effect Surface waves Compression waves Surface waves die exponentially with depth: GO UNDERGROUND!

  24. NN reduction in caves Cave radius [m] 102 less seismic noise x 104 geometrical reduction 106 overall reduction (far from surface) Spherical Cave G.Cella Reduction factor (Compression waves not included) NN reduction of 104 @5 Hz with a 20 m radius cave 5 Hz 10 Hz 20 Hz 40 Hz

  25. 1st generation 2nd generation 3rd generation Underground Newtonian noise Ground surface

  26. NN from compression waves • In a spherical cave NN is reduced as 1/R3 • Beam direction is more important. MAKE LARGE CAVERN ELLIPSOIDAL? Credit: R. De Salvo

  27. A possible design Upper experimental hall 50-100 m well to accomodate long suspension for low frequency goal Ellipsoidal/spherical cave for newtonian noise reduction Credit: R.De Salvo 10 km tunnel

  28. Site identification process Gran Sasso Salt mines

  29. Rotating Neutron Stars 3rd ITF Complementarity with LIGO, VIRGO and LISA Vast range in wavelength (8 orders of magnitude) LISA LIGO/VIRGO Frequency [Hz]

  30. Summary • Expected features of 3rd generation ITF • Triangular configuration • Advanced optical schemes • Low-frequency isolation and suspension • Cryogenic optics • Multiple underground sites • Design study • Develop preliminary ideas • Define site identification process

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