April 19, 2023

THE MONOLITHIC SUSPENSION STATUS FOR THE VIRGO

INTERFEROMETER

THE MONOLITHIC SUSPENSION STATUS FOR THE VIRGO

INTERFEROMETER

Helios VoccaUniversity of Perugia

on behalf of the Virgo collaboration

helios.vocca@pg.infn.it

MG12 Paris - July 12 - 18, 2009 2April 19, 2023

NEW VIRGO+ SENSITIVITY

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=300Qmario=1000No viscousSimple pendulum

10 Hz

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MONOLITHIC SUSPENSIONS MONOLITHIC SUSPENSIONS

Activity tasks Involved Virgo groups:Firenze/UrbinoPerugiaRomaEGO

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 RoomMG12 Paris - July 12 - 18, 2009

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THE MONOLITHIC ASSEMBLY

THE MONOLITHIC ASSEMBLY

Steel box to host the upper silica clamp on the marionetta

Silica Clampson the marionette

Silica anchorsCoupling to the mirror flats through lateral supports

Silicate bonding

MG12 Paris - July 12 - 18, 2009

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FIBRES PRODUCTIONFIBRES PRODUCTION

Laser pulling of 1.5 mm thick silica bars:WeldingAnnealingControlled pulling

100 W CO2 laser

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100 W CO2 laser pulling facility developed in collaboration with Glasgow group

Produced fibres are:Very reproducible in diameter and lengthReady to be characterized and assembled

FIBRES PRODUCTIONFIBRES PRODUCTION

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FIBRES CHARACTERIZATIONFIBRES CHARACTERIZATION

Inspection of the diameter regularity and check of neck reproducibility

Profiles of the necks are equalwithin a 10 μm accuracy level

MG12 Paris - July 12 - 18, 2009

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Measurement of bending lenghts and violin/bouncing frequenciesStatistics on breaking strength

Bending lengths fix the low frequency dynamics of the suspension.

4 GPa

5 kg

Violin mode

Bouncing

Mode (Hz)

Distance between bend.

Points (mm)

453±1 6.0±0.1 669.5±0.2

453±1 6.0±0.1 669.8±0.2

452±1 6.0±0.1 670.2±0.2

451±1 6.0±0.1 669.6±0.2

450±1 6.0±0.1 669.6±0.2

FIBRES CHARACTERIZATIONFIBRES CHARACTERIZATION

MG12 Paris - July 12 - 18, 2009

MG12 Paris - July 12 - 18, 2009 9April 19, 2023

PAYLOAD SUSPENSION AND LOCAL CONTROLPAYLOAD 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

Transportation test (Fi, Pg, Rm with EGO support) on the dummy payload

Mechanical vibration monitored with accelerometersThe test was successful (no broken fibers! untill January 2009: see

next slide);

m/s2

July ‘08 - Shocks, Dust and Humidity tests July ‘08 - Shocks, Dust and Humidity tests

MG12 Paris - July 12 - 18, 2009 10April 19, 2023

Equivalent weight of the mirror is 70 kg at the moment of breakingCrash test movie on youtube (search monolithic crash)

Jan. ‘09 - Shocks, Dust and Humidity tests Jan. ‘09 - Shocks, Dust and Humidity tests

QuickTime™ e undecompressore Sorenson Video 3

sono necessari per visualizzare quest'immagine.

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DUMMY SUSPENSION IN PERUGIADUMMY SUSPENSION IN PERUGIA

Dummy payload installation in the vacuum chamber actuators

shadowmeter

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LOSS MEASUREMENTSLOSS 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

Kp/Ks.b.=2.8 10-14

Kp/Kepoxy=5.6 10-

12

waterglass

epoxy glue

silicate bonding

No excess losses are expected from epoxy or silicate bonding

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LOSS MESUREMENTSLOSS 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

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New (full) suspension is in preparationNew (full) suspension is in preparationSilicate 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

Toward Advanced VirgoToward Advanced Virgo

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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.

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CONCLUSIONSCONCLUSIONS

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 STEPSComplete 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 2009MG12 Paris - July 12 - 18, 2009