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Mining for IMBH Gravitational Waves

Mining for IMBH Gravitational Waves. Fabrizio Barone Enrico Campagna Yanbei Chen Giancarlo Cella Riccardo DeSalvo Seiji Kawamura. Pushing the Low Frequency Limit of ground based GWIDs. Three limiting noise sources impede GWID at Low Frequency

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Mining for IMBH Gravitational Waves

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  1. Mining for IMBH Gravitational Waves • Fabrizio Barone • Enrico Campagna • Yanbei Chen • Giancarlo Cella • Riccardo DeSalvo • Seiji Kawamura LIGO-

  2. Pushing the Low Frequency Limit of ground based GWIDs • Three limiting noise sources impede GWID at Low Frequency • Newtonian Noise (NN, alias Gravity Gradient) • Suspension Thermal Noise (STN) • Radiation Pressure Noise (RPN) • All three can be reduced by means of an underground interferometer LIGO-

  3. Is gravity gradient going to stop us? ~70 Hz LIGO-

  4. Which knobs to turn for low frequency Example: surface LF-GWID (R.DeSalvo, Class. Quantum Grav. 21 (2004)) • In LG-GWID the first limitation is • Newtonian noise, followed by • Suspension thermal noise and • Radiation pressure noise 8 Watts laser Fused Silica Mirror 70 Kg mirror Longer suspensions LIGO-

  5. LF-GWIDthe lowest frequency feasible surface GW detector Bad seismic day Good seismic day ~30 Hz, possibly 20 Hz LIGO-

  6. Newtonian Noise • NN derives from the varying rock density induced by seismic waves around the test mass • It generates fluctuating gravitational forces indistinguishable from Gravity Waves • It is composed of two parts, • The movement of the rock surfaces or interfaces buffeted by the seismic waves • The variations of rock density caused by the pressure waves LIGO-

  7. Newtonian Noise • How to shape the environment’s surface to minimize NN? • The dominant term of NN is the rock-to-air interface movement • On the surface this edge is the flat surface of ground Ground surface LIGO-

  8. Cella Cancellation of NN • If the cavern housing the suspended test mass is shaped symmetrically along the beam line and around the test mass tilting and surface deformations, the dominant terms of NN, cancel out • (with the exception of the longitudinal dipole moment, which can be measured and subtracted). LIGO-

  9. Cella Cancellation of NN • Pressure seismic waves induce fluctuating rock density around the test mass • The result is also fluctuating gravitational forces on the test mass LIGO-

  10. Cella cancellation of NN • Larger caves induce smaller test mass perturbations • The noise reduction is proportional to 1/r3 • The longitudinal direction is more important =>elliptic cave LIGO-

  11. Cella cancellation of NN Cave radius [m] Reduction factor Calculation made for Centered Spherical Cave In rock salt beds 5 Hz 10 Hz 20 Hz 40 Hz Width Length LIGO-

  12. Newtonian Noise gains • Minimal (multiplicative) Gains • ≥ 102 from lower underground activity • ~ 104 from symmetry and size of cave • Gain 101.5 in frequency (=> ~1 Hz) • Now we can try kissing LISA LIGO-

  13. The physics, frequency reach . NN limit Under Ground <|> Above Ground LIGO-

  14. The physics, Universe range 10 1 LIGO- 1 10

  15. Above ground Ad-LIGO: See LIGO document M-0300023-00 LF-GWID: See R.DeSalvo, Class. Quantum Grav. 21S1145-S1154,(2004) G. Conforto, Nucl.Instr.Meth. Vol 518/1-2 pp 228-232 (2004) Limited by Newtonian Noise Under ground Aspen presentation, LIGO-G040036-00-R CEGO proposal, LIGO-T040059-00-R.doc . LIGO-

  16. Reducing the suspension thermal noise • Reduce suspension thermal noise with long suspensions • Noise ~ 1/√L • Suspensions tens of meters long • How to shape the facility to allow this? LIGO-

  17. Vertical cross section A) Upper experimental halls contain all suspension points, readout and control equipment B) Wells (50 to 100 m deep allow for long isolation and suspension wires for LF seismic and STN reduction C) Lower large diameter caves, immune from people’s and seismic Noise reduce the NN LIGO-

  18. How far can we turn the knobs? • Large symmetric underground halls for NN • Longer suspension wires for STN • Large mass mirrors for RPN • Large beam spots for normal TN LIGO-

  19. For lowest frequencies, turn more the sameknobs Suspension Thermal Violin mode LIGO-

  20. Suspension thermal noise limitations • Can make one more step improving the materials (silicon instead of fused silica) getting to 3-4 Hz • After that, cryogenics or alternative solutions will be needed LIGO-

  21. Seismic Attenuation, OKSuspension and Seismic Isolation schematics 10-20 meter pendula Between all stages 2-3 meter tall Pre-isolator In upper cave LF Vertical filters marionetta Composite Mirror Recoil mass LIGO-

  22. You have never seen a seismic attenuation filter • Gosh, where do you come from? • I will show you one! LIGO-

  23. Filter under test Attenuated Payload wire LIGO-

  24. Mirror design - a way out • A clear no action band is present LIGO-

  25. Summarizing • An underground facility permits to overcome or reduce Newtonian, Suspension Thermal and Radiation Pressure Noise the three limitations for Low Frequency operation of GWIDs • Going underground is a very attractive option to explore the IMBH Universe • Chinese scientists got interested and have proposed to their government the construction of an underground GW detection facility CEGO LIGO-

  26. LIGO-

  27. LIGO-

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