THE MONOLITHIC SUSPENSION
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THE MONOLITHIC SUSPENSION STATUS FOR THE VIRGO INTERFEROMETER. Helios Vocca University of Perugia. on behalf of the Virgo collaboration. [email protected] NEW VIRGO+ SENSITIVITY. Sensitivity curve of Virgo+ including monolithic suspensions:.

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THE MONOLITHIC SUSPENSION STATUS FOR THE VIRGO INTERFEROMETER

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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

[email protected]


The monolithic suspension status for the virgo interferometer

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

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.

10 Hz

MG12 Paris - July 12 - 18, 2009


The monolithic suspension status for the virgo interferometer

MONOLITHIC SUSPENSIONS

Involved Virgo groups:

Activity tasks

  • 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


The monolithic suspension status for the virgo interferometer

THE MONOLITHIC ASSEMBLY

Steel box to host the upper silica clamp on the marionetta

Silicate bonding

Silica Clamps

on the marionette

Coupling to the mirror flats through lateral supports

Silica anchors

MG12 Paris - July 12 - 18, 2009


The monolithic suspension status for the virgo interferometer

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


The monolithic suspension status for the virgo interferometer

FIBRES PRODUCTION

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

  • Very reproducible in diameter and length

  • Ready to be characterized and assembled

Produced fibres are:

November 9, 2014

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MG12 Paris - July 12 - 18, 2009


The monolithic suspension status for the virgo interferometer

FIBRES CHARACTERIZATION

Inspection of the diameter regularity and check of neck reproducibility

Profiles of the necks are equal

within a 10 μm accuracy level

MG12 Paris - July 12 - 18, 2009


The monolithic suspension status for the virgo interferometer

FIBRES CHARACTERIZATION

  • Measurement of bending lenghts and violin/bouncing frequencies

  • Statistics on breaking strength

4 GPa

5 kg

Bending lengths fix the low frequency dynamics of the suspension.

November 9, 2014

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MG12 Paris - July 12 - 18, 2009


The monolithic suspension status for the virgo interferometer

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

MG12 Paris - July 12 - 18, 2009


The monolithic suspension status for the virgo interferometer

July ‘08 - Shocks, Dust and Humidity tests

m/s2

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);

November 9, 2014

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MG12 Paris - July 12 - 18, 2009


The monolithic suspension status for the virgo interferometer

Jan. ‘09 - 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)


The monolithic suspension status for the virgo interferometer

DUMMY SUSPENSION IN PERUGIA

shadowmeter

Dummy payload installation in the vacuum chamber

actuators

MG12 Paris - July 12 - 18, 2009


The monolithic suspension status for the virgo interferometer

LOSS MEASUREMENTS

waterglass

silicate bonding

epoxy glue

Kp/Ks.b.=2.8 10-14

Kp/Kepoxy=5.6 10-12

Pendulum oscillation decay measurement loss angle = 2.7 10-7

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

MG12 Paris - July 12 - 18, 2009


The monolithic suspension status for the virgo interferometer

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

If the losses are due to recoil of the supporting structure, a linear relation between Q and mass should be measured

Measure a 1.5 mm fused silica bar welded to the upper block and clamped in the “monolithic suspension” way.

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MG12 Paris - July 12 - 18, 2009


The monolithic suspension status for the virgo interferometer

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

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MG12 Paris - July 12 - 18, 2009


The monolithic suspension status for the virgo interferometer

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.

November 9, 2014

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MG12 Paris - July 12 - 18, 2009


The monolithic suspension status for the virgo interferometer

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


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