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Infrastructure for 3 rd generation interferometers

Infrastructure for 3 rd generation interferometers. Giovanni Losurdo Firenze e-mail: losurdo@fi.infn.it. 1 st generation 2 nd generation 3 rd generation. 10 2. Credit: M.Punturo. 1 st generation. NEW laser, suspensions, optical scheme, mirrors

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Infrastructure for 3 rd generation interferometers

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  1. Infrastructure for 3rd generation interferometers Giovanni Losurdo Firenze e-mail: losurdo@fi.infn.it

  2. 1st generation 2nd generation 3rd generation 102 Credit: M.Punturo EAP Town Meeting – Munich, Nov. 23, 2005G.Losurdo –Firenze-Urbino2

  3. 1st generation NEW laser, suspensions, optical scheme, mirrors Same infrastructure 2nd generation NEW laser, suspensions, optical scheme, mirrors, vibration isolators. Cryogenics. NEW INFRASTRUCTURE 3rd generation EAP Town Meeting – Munich, Nov. 23, 2005G.Losurdo –Firenze-Urbino3

  4. Interferometer size Detector geometry Low frequency goal Impact on infrastructure EAP Town Meeting – Munich, Nov. 23, 2005G.Losurdo –Firenze-Urbino4

  5. Longer detectors • Length of 1st generation detectors (Virgo - 3 km, LIGO - 4 km) mainly limited by cost of vacuum/infrastructures • A 10 km detector is technically feasible • Easy way to improve sensitivity PHASE = const. x GW amplitude x detector armlength EAP Town Meeting – Munich, Nov. 23, 2005G.Losurdo –Firenze-Urbino5

  6. Co-located detectors • LIGO Hanford - two co-located interferometers: REDUNDANCY • Half length detector responds to GW with half amplitude • Same vacuum pipe, same orientation: no information on the polarization! EAP Town Meeting – Munich, Nov. 23, 2005G.Losurdo –Firenze-Urbino6

  7. Rüdiger idea 3 detectors in TRIANGLE configuration Rüdiger, ‘85 2 polarizations measured + redundancy EAP Town Meeting – Munich, Nov. 23, 2005G.Losurdo –Firenze-Urbino7

  8. Square configuration maximises the response to GW, 13% of signal lost with triangular configuration. But… • No “zeroes “ in the overall antenna pattern • Better overlap with far detectors Figure: M.Lorenzini EAP Town Meeting – Munich, Nov. 23, 2005G.Losurdo –Firenze-Urbino8

  9. Antenna patterns Credit: Cella, Vicerè LIGO Virgo Angular response of a standard ITF Angular response of the triangle configuration EAP Town Meeting – Munich, Nov. 23, 2005G.Losurdo –Firenze-Urbino9

  10. 1st - 2nd generation 10 Hz cutoff Ultra Low Frequency: 1Hz 3rd generation 1 Hz cutoff One more decade at low frequency EAP Town Meeting – Munich, Nov. 23, 2005G.Losurdo –Firenze-Urbino10

  11. Isolation requirements Required isolation @1 Hz: at least 1010 with ground noise. • Ultra soft vibration isolation • Very long pendulums (50, 100 m) • Very good thermal stabilization • Ultra performant active platforms • Very low noise sensors • Very good thermal stabilization • Very low tilt noise • Very quiet site EAP Town Meeting – Munich, Nov. 23, 2005G.Losurdo –Firenze-Urbino11

  12. Not only seismic noise… Credit: I.Fiori • 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 EAP Town Meeting – Munich, Nov. 23, 2005G.Losurdo –Firenze-Urbino12

  13. Low seismicity sites No tectonics, no oceans, no wind Negligible seismic activity We will not ask for the MOON maybe in FP 27… Low seismicity on Earth? UNDERGROUND EAP Town Meeting – Munich, Nov. 23, 2005G.Losurdo –Firenze-Urbino13

  14. 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 Courtesy: K.Kuroda EAP Town Meeting – Munich, Nov. 23, 2005G.Losurdo –Firenze-Urbino14

  15. 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 Courtesy: K.Kuroda EAP Town Meeting – Munich, Nov. 23, 2005G.Losurdo –Firenze-Urbino15 Hz

  16. Newtonian noise SEISMIC NOISE Isolation shortcircuit Figure: M.Lorenzini EAP Town Meeting – Munich, Nov. 23, 2005G.Losurdo –Firenze-Urbino16

  17. Newtonian noise estimate Cella-Cuoco, 98 EAP Town Meeting – Munich, Nov. 23, 2005G.Losurdo –Firenze-Urbino17

  18. 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! EAP Town Meeting – Munich, Nov. 23, 2005G.Losurdo –Firenze-Urbino18

  19. NN reduction in caves Cave radius [m] 102 less seismic noise x 104 geometrical reduction 106 overall reduction (far from surface) Reduction factor (Compression waves not included) Spherical Cave G.Cella NN reduction of 104 @5 Hz with a 20 m radius cave 5 Hz 10 Hz 20 Hz 40 Hz EAP Town Meeting – Munich, Nov. 23, 2005G.Losurdo –Firenze-Urbino19

  20. 1st generation 2nd generation 3rd generation Underground Newtonian noise Ground surface EAP Town Meeting – Munich, Nov. 23, 2005G.Losurdo –Firenze-Urbino20

  21. 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 EAP Town Meeting – Munich, Nov. 23, 2005G.Losurdo –Firenze-Urbino21

  22. A possible design Upper experimental hall Space for an advanced resonant detector 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 EAP Town Meeting – Munich, Nov. 23, 2005G.Losurdo –Firenze-Urbino22

  23. EAP Town Meeting – Munich, Nov. 23, 2005G.Losurdo –Firenze-Urbino23

  24. The Great Unification…in Europe If we cannot put the fundamental interactions into the same theory… we can at least put them in the same place! EAP Town Meeting – Munich, Nov. 23, 2005G.Losurdo –Firenze-Urbino24

  25. Or… GRAN SASSO undeground lab EAP Town Meeting – Munich, Nov. 23, 2005G.Losurdo –Firenze-Urbino25

  26. Or… SALT MINES: easy to dig big caves with arbitrary shape R.De Salvo, Aspen 05 EAP Town Meeting – Munich, Nov. 23, 2005G.Losurdo –Firenze-Urbino26

  27. Summary 3rd generation interferometers should be longer: 10 km Three nested detectors in triangular configuration will improve sky coverage, vetoing and give infos on GW polarization 3rd generation detector must be undeground to achieve the 1 Hz goal Preliminary ideas, to be developed in a design study EAP Town Meeting – Munich, Nov. 23, 2005G.Losurdo –Firenze-Urbino27

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