1. September 8, 2015 THE MONOLITHIC SUSPENSION STATUS FOR THE VIRGO INTERFEROMETER THE MONOLITHIC SUSPENSION STATUS FOR THE VIRGO INTERFEROMETER Helios Vocca University of Perugia on behalf of the Virgo collaboration helios.vocca@pg.infn.it

2. MG12 Paris - July 12 - 18, 2009 2September 8, 2015 NEW VIRGO+ SENSITIVITY New thermal noise evaluation by Piergiovanni, Punturo and Puppo includes the viscous contribution of the marionette Sensitivity curve of Virgo+ including monolithic suspensions: F. Piergiovanni, M.Punturo, P.Puppo, The thermal noise of the Virgo+ and Virgo Advanced Last Stage Suspension (The PPP effect), Virgo Note: VIR-015C-09. Qmario=300 Qmario=1000 No viscous Simple pendulum 10 Hz

3. 3September 8, 2015 MONOLITHIC SUSPENSIONS Activity tasks Involved Virgo groups:  Firenze/Urbino  Perugia  Roma  EGO General Strategy for Monolithic Suspensions Planning:  Payload parts assembled in the new 1500West Clean Room  Mirrors prepared at LMA (Lyon)  IF Possible (by cleanliness tests): payloads assembled in 1500W Clean Room MG12 Paris - July 12 - 18, 2009

4. 4September 8, 2015 THE MONOLITHIC ASSEMBLY Steel box to host the upper silica clamp on the marionetta Silica Clamps on the marionette Silica Clamps on the marionette Silica anchors Coupling to the mirror flats through lateral supports Silicate bonding MG12 Paris - July 12 - 18, 2009

5. 5September 8, 2015 FIBRES PRODUCTION Laser pulling of 1.5 mm thick silica bars:  Welding  Annealing  Controlled pulling 100 W CO2 laser MG12 Paris - July 12 - 18, 2009

6. 6September 8, 2015 100 W CO2 laser pulling facility developed in collaboration with Glasgow group Produced fibres are:  Very reproducible in diameter and length  Ready to be characterized and assembled FIBRES PRODUCTION MG12 Paris - July 12 - 18, 2009

7. 7September 8, 2015 FIBRES CHARACTERIZATION Inspection of the diameter regularity and check of neck reproducibility Profiles of the necks are equal within a 10 μ m accuracy level MG12 Paris - July 12 - 18, 2009

8. 8September 8, 2015  Measurement of bending lenghts and violin/bouncing frequencies  Statistics on breaking strength Bending lengths fix the low frequency dynamics of the suspension. 4 GPa 5 kg Violin modeBouncing Mode (Hz) Distance between bend. Points (mm) 453±16.0±0.1669.5±0.2 453±16.0±0.1669.8±0.2 452±16.0±0.1670.2±0.2 451±16.0±0.1669.6±0.2 450±16.0±0.1669.6±0.2 FIBRES CHARACTERIZATION MG12 Paris - July 12 - 18, 2009

9. 9September 8, 2015 PAYLOAD SUSPENSION AND LOCAL CONTROL marionette and coils mirror and magnets reaction mass  Steel AlSl304 Marionetta prototype with PVC arms  Dummy reaction mass, coils with peek supports  A mirror is inserted in the holder and the system is balanced  All the pieces are secured by safety structures  Fibre bending points placed on the marionetta and mirror CoM

10. Transportation test (Fi, Pg, Rm with EGO support) on the dummy payload Mechanical vibration monitored with accelerometers The test was successful (no broken fibers! untill January 2009: see next slide); m/s 2 July ‘08 - Shocks, Dust and Humidity tests MG12 Paris - July 12 - 18, 2009 10September 8, 2015

11. Equivalent weight of the mirror is 70 kg at the moment of breaking Crash test movie on youtube (search monolithic crash) Jan. ‘09 - Shocks, Dust and Humidity tests

12. 12September 8, 2015 DUMMY SUSPENSION IN PERUGIA Dummy payload installation in the vacuum chamber actuators shadowmeter MG12 Paris - July 12 - 18, 2009

13. 13September 8, 2015 LOSS MEASUREMENTS Pendulum oscillation decay measurement loss angle = 2.7 10 -7 Evidence of excess losses, maybe recoil or support losses  Further investigation needed, measurements in progress K p /K s.b. =2.8 10 -14 K p /K epoxy =5.6 10 -12 waterglass epoxy glue silicate bonding No excess losses are expected from epoxy or silicate bonding MG12 Paris - July 12 - 18, 2009

14. 14September 8, 2015 LOSS MESUREMENTS Tests are going on to identify the source of excess loss: Measure a 1.5 mm fused silica bar welded to the upper block and clamped in the “monolithic suspension” way. Friction in the support: direct upper clamp measurement Recoil losses: measurement with new suspension If the losses are due to recoil of the supporting structure, a linear relation between Q and mass should be measured Different loads (1 kg, 3 kg, 5 kg…) suspended using two marionette-like clamps MG12 Paris - July 12 - 18, 2009

15. 15September 8, 2015 MG12 Paris - July 12 - 18, 2009 New (full) suspension is in preparation Silicate bonding has been made 2 weeks ago in Lyon clean room. In august the FS suspension will be mounted. Measurements on it will go on in Cascina and Perugia

16. Toward Advanced Virgo 16September 8, 2015 MG12 Paris - July 12 - 18, 2009 Even if a final geometry for AdV mirrors has not been decided yet, an important evolution will be to remove the silicate bonded supports for the monolithic suspension.

17. 17September 8, 2015 CONCLUSIONS  Fiber production validated and well defined;  Monolithic design for fused silica components is ok;  Payloads are under construction;  Virgo mirror (old north end) with supports, markers and magnets ready to be suspended; NEXT STEPS  Complete FS suspension to be performed in summer in the new 1500W clean room (almost ready);  Measurements of the mechanical losses and identification of the excess losses will follow;  Final design of the assembly structure to be fixed. Ready to install at the end of 2009 MG12 Paris - July 12 - 18, 2009