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Advanced Virgo BASELINE DESIGN

advanced

Giovanni Losurdo – INFN Firenze

Advanced Virgo Coordinator

for the Virgo Collaboration

ILIAS Annual Meeting – Tubingen, Oct 9, 2007 G.Losurdo – INFN Firenze 2

advanced ADVANCED VIRGO (AdV)

Upgrade of Virgo+, “minor” modifications to the facilities and to the SA

Sensitivity goal: about 10x better than Virgo

Main foreseen changes:

– higher power (optical readout noise)

– heavier mirrors (optical readout noise)

– better coatings (thermal noise)

– signal recycling (shape the curve)

– beam waist position (thermal noise)


advanced ONGOING AdV R&D – SUMMARY (I)

Fiber laser and IMC

Optics forhigh power

Detection system

Mirror coating Mirror cleaning

Optical config. design(Post‐doc@B’ham)

Prototyping/locking(CALVA)New modal optics


advanced ONGOING AdV R&D – SUMMARY (II)

Tiltmeter

Marionette RMCleanliness

Ribbons formonolithic susp.

(Glasgow)

Electrostatic act.

IP upgrade


advanced STATUS

AdV conceptual design completed

– Internal review in progress

– Due to STAC (advisory panel) and EGO Council (funding agencies) by the end of the month

Waiting for the funding agencies approval

– New organization being setup. From Working Groups to WBS.

– Next two years to prepare the AdV technical design.

advanced

AdV BASELINE


advanced LASER

BASELINE:

200 W SOLID STATE LASER AMPLIFIER (LZH for Advanced LIGO)Nice Group is already collaborating with LZH for the Virgo+ amplifier.

ALTERNATIVE OPTION:

FIBER LASER AMPLIFIER (R&D Nice‐Limoges): promising research line

– stabilization to be done

– non linear effects and polarisation maintaining to be investigated at HP


advanced INPUT OPTICS

BASELINE:

144 m SUSPENDED RESONANT IMC: Virgo‐like solution. Problem of small

angle diffused light to be addressed.

EOM – FARADAY: Advanced LIGO solution.

AdvLIGO EOM

AdvLIGO Faraday

ALTERNATIVE OPTION:

FIBER LASER IMC (R&D Nice‐

Limoges): promising research line,

would be a major simplification.


advanced SIGNAL RECYCLING

BASELINE:

“WIDEBAND” SR – Optical parameters to be defined.

The base for the SR tower is there!


advanced OPTICAL LAYOUT ‐ DETECTION

seetalk

byA.F

reise

OPT. LAYOUT BASELINE:

TEM00

WAIST IN THE CAVITY CENTER

LARGER BEAM: requires changing

the vacuum links in the central area.

DET. BASELINE:

PHOTODIODES IN VACUUM

DC DETECTION


advanced MIRRORS

ALTERNATIVE OPTION:

EVEN HEAVIER TEST MASSES (60 Kg?)

Useful if fiber geometry is optimized

BASELINE:

35 cm diam. 20 cm thick, 42 Kg

SUBSTRATES

STATE OF ART COATINGS


advanced SUPERATTENUATOR ‐ IP

BASELINE:

VIRGO DESIGN with STIFFER IP LEGS

TILTMETER AND IP 6 DOF CONTROL

MECHANICS: NEW MARIONETTE REFERENCE MASS

MIRROR ACTUATION: COIL‐MAGNET PAIRS

ALTERNATIVE OPTION:

ELECTROSTATIC ACTUATORS: noise specs to be

demonstrated


advanced SUSPENSIONS

BASELINE:

FUSED SILICA CYLINDRICAL FIBERS

ALTERNATIVE OPTION:

FUSED SILICA RIBBONS

DUMBBELL FIBERS

Virgo+ studies: The dummy mirrorsuspended withsilica fibers


advanced AdV BASELINE ‐ SUMMARY

heavier mirrors(42 kg)

high finesse (≈1000)

larger beam waist

DC detection

signal recycling

new IPtilt control

new payload

fused silicasuspensions

high power SSL(200 W)


advanced SENSITIVITY CURVE ‐ preliminary

BNS range: 121 Mpc

BBH range: 856 Mpc

1 kHz sens.: 6 10‐24

SR mirror transmittance: 0.04

Input mirror transm: 0.007

Finesse: 885

PR factor: 23.5

Power on BS: 2.9 kW


advanced BNS/BBH inspiral range vs tIN‐tSR

128‐717

127‐758

125‐805

121‐859

111‐912

0.007

124‐782127‐743128‐678128‐584115‐4290.1

122‐818125‐783128‐718129‐620118‐4720.08

118‐857123‐829126‐764130‐659120‐4700.06

112‐898118‐880123‐817129‐699122‐4700.04

101‐925108‐925114‐871122‐729121‐4140.02

0.010.0080.0060.0040.002tSR tIN

Lower FP cavity finesseLower

SR m

irrortransm

ittance

BLUE = BNS inspiral rangeRED = BBH inspiral range


advanced AdV sensitivity vs Fiber geometry

959859BBH

126121BNS

2.9 kWPBS

23.5G

885Finesse

ribboncylindricalfiber

geometry

The ribbon choice reduces considerably the contribution of

suspensions thermal noise

Dumbbell fibers can also improve the performance

The benefits on the sensitivity are limited by radiation pressure,

newtonian and CONTROL NOISE (unmodelled so far)


advanced HEAVIER MIRRORS?

If ribbons are used, low frequency sensitivity can be further improved

by using thicker mirrors (30 cm diam., 63 kg mass)

The low frequency sensitivity is then limited by newtonian noise

(model uncertain) and coating brownian noise

1053859BBH

130121BNS

2.9 kWPBS

23.5G

885Finesse

ribbon63 Kg mirr

BASELINEfiber

geometry


advanced TWO‐STEP STRATEGY?

We are considering the idea of a two‐step strategy:

– Start AdV WITHOUT SR mirror and learn to operate the power recycledinterferometer with high power

– Add the SR mirror afterwards

A good “intermediate” sensitivity can be achieved, even better with

heavier mirrors

Power rec AdV

BNS range: 97 MpcBBH range: 265 Mpc1 kHz sens.: 2 10‐23


advanced CONCLUSION

A baseline design for AdV has been proposed

Possible changes to the baseline will be considered (on the strength

of the R&D progress) and discussed next year within a new AdV

organization

See next talk by A.Freise and P.Puppo for more details


advanced INVITATION

AdV is moving towards a new phase: the preparation of the

TECHNICAL DESIGN

There are many things to do and we are open to enlarge the

Collaboration for Advanced Virgo

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