virgo: plans for the next future virgo+

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Virgo: Plans for the next future Virgo+ Michele Punturo INFN Perugia On behalf of the Virgo collaboration 27/05/2006 -2/06/2006 GWADW-VESF Meeting

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Virgo: Plans for the next future Virgo+. Michele Punturo INFN Perugia On behalf of the Virgo collaboration. 27/05/2006 -2/06/2006 GWADW-VESF Meeting. Sensitivity & Detection. Detection performances:. BNS. Sensitivity improvement. The nominal Virgo sensitivity is dominated by - PowerPoint PPT Presentation

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Page 1: Virgo: Plans for the next future Virgo+

Virgo: Plans for the next future

Virgo+

Michele PunturoINFN Perugia

On behalf of the Virgo collaboration

27/05/2006 -2/06/2006 GWADW-VESF Meeting

Page 2: Virgo: Plans for the next future Virgo+

2

Sensitivity & Detection

10 100 1000 1000010-23

10-22

10-21

10-20

10-19

10-18

10-17

10-16

h(

f) [1/

sqrt(H

z)]

Frequency [Hz]

C7 sensitivity Nominal Virgo "Dec2006" Virgo

Detection performances:

Source Virgo (SNR=8)

NS-NS

1.4-1.4Ms

31.0 Mpc

(12.4)

BH-BH

10-10Ms

145 Mpc

(58)

Burst

hrss≈10-20 1kpc

12.9kpc

BNS

Page 3: Virgo: Plans for the next future Virgo+

3

Sensitivity improvement• The nominal Virgo sensitivity is dominated by

– the shot noise, at high frequency– the pendulum thermal noise at low frequency

1 10 100 1000 1000010-23

10-22

10-21

10-20

10-19

10-18

(a) Virgo Nominal sensitivity (b) Seismic noise (c) Pendulum thermal noise (d) Mirror thermal noise (e) Shot Noise

h(f) [1/

sqrt(H

z)]

Frequency [Hz]

(a)

(b)

(c)

(d)

(e)

Page 4: Virgo: Plans for the next future Virgo+

4

High Power Lasers Light

• Reduction of the shot noise passes through the increase of the power of the light circulating in the Fabry-Perot Cavities– In a shot-noise limited detector the sensitivity decreases as

– Currently the laser is a 20W, supplied by the Laser Zentrum Hannover, based on a Nd:YVO4 rod, end pumped by fibre-coupled diode lasers

– High power laser is necessary to inject many Watts in the cavities• Current technology, developed by the GEO-Hannover group+LZH, permits to

have hundred Watts CW lasers • Many technical problems on the injection and central optics limit the possible

increase of power, with a reduced impact on the shut-down period– 50 W seems a good compromise between the noise improvement and the technical

difficulties

laserP

1

Page 5: Virgo: Plans for the next future Virgo+

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Nd:YVO4 for 50W Amplifier

• 50W laser amplifier under development between LZH and Virgo:

Four-stage end-pumped Nd:YVO4Each stage pumped by 45 W laser diodeEach diode indiv temp controlledEach 2diodes connected in series to 1 current driverDiodes current controlled

(LZH prop)

• Possibility to replace the current master laser with a fiber laser

Page 6: Virgo: Plans for the next future Virgo+

6

Possible laser system

20W laser(injection-locked )

Pre Mode Cleaner

Master Laser

Nd-YvO4 crystal

Crystal pumping module

40WAmplifier module

Page 7: Virgo: Plans for the next future Virgo+

7

50/2 W laser effect

• NS-NS signal detection benefits of the improved sensitivity at high frequency

1 10 100 1000 1000010-23

10-22

10-21

10-20

10-19

h(f) [1

/sqrt(H

z)]

Frequency [Hz]

Nominal Virgo Virgo 50W-laser

Source Virgo 50 W

(dist. Mpc)

NSNS 37.4 (15.0)

BHBH 172 (68.8)

Page 8: Virgo: Plans for the next future Virgo+

8

Mirror Losses New Model• The Virgo nominal sensitivity is realized adopting a constant in frequency

model for the mirror Brownian noise• S.D.Penn et al. shown that this corresponds to an over-estimation of that

noise and they proposed a model for Suprasil 312:813.0129

42

1

1 1063.41012.71

,3

fV

SC

Hz

fC

S

VC

V

Sf elasticth

C

VirgoMirrors

Region of interest forthermal noise in adv Virgo

910bulk

• But the current Virgo Input Mirrors are made in Suprasil 311-SV very similar to Suprasil-312– Reducing the other noises we should have an “advanced” performance level

S.D.Penn et al., Phys. Lett. A 2006, 352 (1-2), 3-6

Page 9: Virgo: Plans for the next future Virgo+

9

Replacement of the Virgo mirrors

• Virgo mirror are in a “mixed” configuration– Input mirrors in Suprasil SV-311 (low losses)– End mirrors in Herasil (High losses, no

frequency dependence (Numata et al.))

• Replacing all the mirrors we could– Use low dissipation material for all the mirrors– Adopt better performance coatings– Install monolithic fused silica suspension

Page 10: Virgo: Plans for the next future Virgo+

10

10 100 1000 1000010-25

10-24

10-23

10-22

h(f) [1

/sqrt(H

z)]

Frequency [Hz]

(a) Total mirror thermal noise (new model) (b) New bulk Brownian noise evaluation (c) New coating Brownian evaluation (d) Total mirror thermal noise (old model)

(a)

(b)

(c)

(d)

Mirror thermal noise evaluation• R&D activities in LIGO with the support of the LMA-Virgo group

demonstrated that it is possible to decrease the mechanical dissipation of the coatings introducing TiO2 dopants in the Ta2O5/SiO2 layers

(d) Evaluated withTa2O5=4×10-4,

Subs≈10-6-10-7

(b) Evaluated with Subs Penn’s Model

(c ) Evaluated withTa2O5=1.6×10-4

(a) Incoherent sum:

...)()()( 22 cba

Page 11: Virgo: Plans for the next future Virgo+

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New mirrors and 50W laser amplifier

• NS-NS signal detection benefits of the improved sensitivity at intermediate frequency

1 10 100 1000 1000010-23

10-22

10-21

10-20

10-19

10-18

h(f) [1

/sqrt(H

z)]

Frequency [Hz]

50W/2 + new losses model 50W/2 + current mirrors Nominal Virgo

Page 12: Virgo: Plans for the next future Virgo+

12

Complete the upgrade• In effect, the previous improvement is “incomplete”

and maybe “fictitious”:– To substitute four mirrors we need to invest a lot of

money, a large effort and a long shutdown period• Large cost of the substrates• Large cost of the coatings• At least one month of preparatory work for each mirror before to

shut-down the ITF and 3 weeks to install each payload• Presence of a large excess loss due to the friction of the

suspension wires on the mirror lateral faces.

– Steel wire suspension is not the selected technology for the 2nd generation (“advanced”) detectors

• Could we anticipate the upgrade of the suspension? • Virgo have already a second generation seismic filtering system!

Page 13: Virgo: Plans for the next future Virgo+

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• Thanks to the well known low mechanical dissipation of the fused silica, a similar monolithic suspension promises an excellent performance in terms of thermal noise

• Multi-year R&D activity performed in Virgo• Collaboration with the GEO-Glasgow group• Large engineering effort now in Virgo to realize a FS monolithic last stage

– Two fiber production machines available in Cascina• H2-O2 flames “standard” machine completely automated• New CO2 laser machine

– Well defined planning available• Realization of a test payload having

– Stainless steel marionette

– Dielectric reference mass

– Monolithic fused silica suspension fibers attached to the mirror through silicate bonding

– Dummy mirror

– Full Virgo local control system

» Magnet-Coil actuation system

» Digital (ADC-DSP-DAC) control system

» Optical lever monitoring

Monolithic fused silica suspension

Page 14: Virgo: Plans for the next future Virgo+

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Fiber production Facilities

H2-O2 gasses Machine

CO2 laser Machine

Page 15: Virgo: Plans for the next future Virgo+

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1 10 100 1000 1000010-23

10-22

10-21

10-20

10-19

10-18

h(f) [1

/sqrt(H

z)]

Frequency [Hz]

50W/2 + new losses model 50W/2 + current mirrors Nominal Virgo 50W/2 + new losses model+FS suspensions

Virgo+ performances 1/2

• NS-NS signal detection benefits of the improved sensitivity at intermediate frequency

• Too optimistic view:– The Gravity gradient noise

“obscure” the low frequency part

– Cella-Cuoco model:

fxf

fh seismNN 2

11103

Page 16: Virgo: Plans for the next future Virgo+

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1 10 100 1000 1000010-23

10-22

10-21

10-20

10-19

10-18

h(f) [1

/sqrt(H

z)]

Frequency [Hz]

50W/2 + new losses model 50W/2 + current mirrors Nominal Virgo 50W/2 + new losses model+FS suspensions Virgo+ with Newtonian Noise

Virgo+ performances 2/2• Too optimistic view:

– The Gravity gradient noise “obscure” the low frequency part

– Cella-Cuoco model:

Virgo+ (NN)

Mpc

Curve (b)

Mpc

NSNS 114 (45.6) 121 (48.2)

BHBH 584 (234) 664 (265)

(NN)(b)

fxf

fh seismNN 2

11103

• The low frequency limit due to the Newtonian noise weakly affects the NSNS detection performances

Page 17: Virgo: Plans for the next future Virgo+

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What is necessary?• Physicists are fascinated by fundamental noises and frustrated by

technical ones– Control noises are currently limiting the low frequency sensitivity of all the GW

ITFs in the World

– In particular, the required low frequency performances of Virgo and furthermore of Virgo+ are a challenging stress test of:

• Actuation electronics– New coil drivers with lower noise under realization

– New DACs with a larger dynamic range under study

• DAQ electronics– New ADC with higher sampling frequency and number of bits under study

• “Filtering” electronics– New generation DSP boards with high computational power under realization (to fulfill

the increasing request of CPU power)

– High power laser requires• Upgrade of some components in our input and detection optics• Thermal compensation devices

– Absorption in the input mirror is suppressed by the good quality of our mirror substrates

» Nevertheless a thermal compensation system is under study (LIGO+GEO experience)

Page 18: Virgo: Plans for the next future Virgo+

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Advanced Virgo•Design Activity still not started•R&D activities on

•High power lasers•Signal recycling and optical topologies•Coatings•Electrostatic actuators

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Page 19: Virgo: Plans for the next future Virgo+

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Conclusions• In the next months Virgo will approach his final sensitivity• A series of well defined upgrades will permit to increase

the detector performances with a relatively small impact on the operational time:– Virgo+ is currently an engineering effort rather than a R&D

activity

• A huge R&D activity is, instead, necessary to arrive to the Advanced Virgo design