THE MONOLITHIC SUSPENSION STATUS FOR THE VIRGO INTERFEROMETER

Transcription

1 THE MONOLITHIC SUSPENSION STATUS FOR THE VIRGO INTERFEROMETER Helios Vocca University of Perugia on behalf of the Virgo collaboration

2 NEW VIRGO+ SENSITIVITY Sensitivity curve of Virgo+ including monolithic suspensions: New thermal noise evaluation by Piergiovanni, Punturo and Puppo includes the viscous contribution of the marionette Qmario=300 Qmario=1000 No viscous Simple pendulum 10 Hz 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. 2

3 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 3

4 THE MONOLITHIC ASSEMBLY!"##$%&'(%"'%)'*"%")#%+,,#-%*.$./0 /$01,%'2%")#%10-.'2#30!.$./0"#%&'27.25!.$./0%4$01,* '2%")#%10-.'2#3#!.$./0%02/)'-* 4'+,$.25%"'%")#%1.--'-%60"*%")-'+5)%$0"#-0$%*+,,'-"* 4

5 FIBRES PRODUCTION 100 W CO2 laser Laser pulling of 1.5 mm thick silica bars:!welding!annealing!controlled pulling 5

6 FIBRES PRODUCTION 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 6

7 FIBRES CHARACTERIZATION Inspection of the diameter regularity and check of neck reproducibility Profiles of the necks are equal within a 10 µm accuracy level 7

8 FIBRES CHARACTERIZATION!Measurement of bending lenghts and violin/bouncing frequencies!statistics on breaking strength 4 GPa 5 kg Violin mode Bouncing Mode (Hz) Distance between bend. Points (mm) 453±1 6.0± ± ±1 6.0± ± ±1 6.0± ± ±1 6.0± ± ±1 6.0± ±0.2 Bending lengths fix the low frequency dynamics of the suspension. 8

9 PAYLOAD SUSPENSION AND LOCAL CONTROL 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 marionette and coils reaction mass mirror and magnets 9

10 July 08 - Shocks, Dust and Humidity tests m/s 2 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); 10

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

12 DUMMY SUSPENSION IN PERUGIA shadowmeter Dummy payload installation in the vacuum chamber actuators 12

13 LOSS MEASUREMENTS waterglass silicate bonding epoxy glue K p /K s.b. = K p /K epoxy = Pendulum oscillation decay measurement loss angle = No excess losses are expected from epoxy or silicate bonding Evidence of excess losses, maybe recoil or support losses! Further investigation needed, measurements in progress 13

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

15 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 15

16 Toward Advanced Virgo 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. 16

17 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