Present SA performance vs. AdV & ET Specs

S.Braccini for Virgo Suspension group

Passive Attenuation

Ground

Mirror

Resonances

f-2N

Long Pendula

2 Hz

Tran

smis

sion

Soft Springs

Frequency (Hz)

Blade Springs

MagneticAntisprings

8 m

Ground Seismic NoiseMirror Seismic Noise

Rumore Termico

DL(f) = h(f) / 3000

TFmax = DL(f) /(LSD Ground Seismic Noise)

LSD Ground Seismic Noise = 5 x 10 -7/ f 2

Same Exercise for ET sensitivity

DL(f) = h(f) / 10000

TFmax = DL(f) /(LSD Under-Ground Seismic Noise)

LSD Ground Seismic Noise (Kamioka) - 5 x 10 -9/ f 2

(Duzel Mine much better)

Same Exercise for ET-Xylophone sensitivity

DL(f) = h(f) / 10000

TFmax = DL(f) /(LSD Ground Seismic Noise)

LSD Ground Seismic Noise (Kamioka) - 5 x 10 -9/ f 2

Valid both for horizontal and vertical seismic noise

SA designe freccette

Filter Chain TF measurements(without Pre-Isolator !)

SA designe freccette

@ 4.1 Hz< 6 ×10e-8

CITF Measurements around 2, 4, 9 Hz

SA designe freccette

CITF Measurements around 2, 4, 9 Hz

@ 2.25 Hz5 ×10e-6

High Sens Range

Larger stabilityallows longer measurements

SA designe freccette

frequency (Hz)

Displacement (m .Hz-1/2)

Top

Mirror

Transfer Function < 10-10

StressedMeasurement

T = 41943 sHigh Sens Range

TOP

MIRROR

2 x 10-18 m Hz-1/2

1.2 x 10-6 m Hz-1/2

TF < 1.7 x 10-12

!!

TF = 1.26 x 10-11

ET-Xylophone AdV

1.26 x 10-11

+ Pre-Isolator

SA designe freccette

X-excitation

SA designe freccette

Possible Bypass

Bypass Indication ?

X - Excitation Results

HORIZONTAL

Integration Time Kind of Measurement FrequencyDisp Top

(Lines LSD) Disp Mirror Upper Limit (LSD) TF(s) (Hz) (m Hz^-1/2) (m Hz^-1/2)

10485 Central interferometer 2,30 4,80E-05 2,50E-10 5,21E-0610485 Central interferometer 4,10 3,30E-05 2,00E-12 6,06E-08

About 20000 s West Input Cavity Mirror 4,30 4,31E-06 3,6E-14 8,36E-09About 20000 s West Input Cavity Mirror 6,30 6,02E-06 5,4E-14 8,97E-09

10485 Central interferometer 9,80 5,70E-06 4,10E-13 7,19E-08About 20000 s West Input Cavity Mirror 10,30 3,00E-06 1,8E-16 6,00E-11About 20000 s West Input Cavity Mirror 18,30 2,85E-06 4,8E-17 1,68E-11

41943 North Input Cavity Mirror 29,30 2,95E-06 1,50E-17 5,08E-1241943 West Input Cavity Mirror 30,30 9,39E-07 6,00E-17 6,39E-1141943 North End Cavity Mirror 31,30 1,42E-06 1,80E-17 1,26E-1141943 West End Cavity Mirror 32,30 1,22E-06 2,4E-18 1,97E-12

VERTICALIncluded H-V Coupling

Integration Time Kind of Measurement FrequencyDisp Top

(Lines LSD) Disp Mirror Upper Limit (LSD) TF(s) (Hz) (m Hz^-1/2) (m Hz^-1/2)

2620 Central Interferometer 2,25 1,70E-04 2,60E-10 1,53E-062620 Central Interferometer 4,10 3,00E-04 3,00E-12 1,00E-08

25165 North Input Cavity Mirror 29,30 1,22E-06 3,00E-18 2,47E-1225165 West Input Cavity Mirror 30,30 3,88E-06 3,00E-18 7,73E-1325165 North End Cavity Mirror 31,30 4,14E-06 3,00E-18 7,24E-1325165 West End Cavity Mirror 32,30 4,43E-06 3,00E-18 6,77E-13

X-AXIS8388 North Input Cavity Mirror 29,30 1,18E-06 3,9E-17 3,30E-118388 West Input Cavity Mirror 30,30 6,08E-07 1,26E-17 2,07E-118388 North End Cavity Mirror 31,30 6,3E-07 3,9E-18 6,19E-128388 West End Cavity Mirror 32,30 7,53E-07 2,31E-17 3,07E-11

Red = Line DetectedBlue = Line Not Detected

Purple = Upper Limitnot useful (too large)

ET-Xylophone AdV

Upper Limit Detected

Without Pre-Isolator (Just filter chain !)

53113

IP Guarantees for this !Already compliant for ET

(Remind that we are speaking of Upper Limits !)

Vertical TF measurements(Coupling included in the measurement)

Vertical Measurements

ET-Xylophone AdV

Without Filter Zero (Just filter chain !)

60

F0 Guarantees for thisUPPER LIMIT (!) compliant for ET

Vertical Upper Limit Vertical Detected

Preisolator makes safetymargin wide in AdV

SA are compliant also for ET starting from 4 Hz....

What happens below?

@ 2.25 Hz5 ×10e-6

Remarkable Attenuation also at 2.25 Hz

HORIZONTAL

@ 2.25 Hz1.5 ×10e-6

Remarkable Attenuation also at 2.25 Hz

VERTICAL

Yes

No

Maybe

423

TF

f

ModelMeas.

Stage by Stage Measurement (and Model)

ET Design Programme

Cut-off 3-4 Hz No Design Study

Cut-off 1-2 Hz Design Study

SCIENCE CASE & NEWTONIAN NOISETO BE DISCUSSED AT ERICE MEETING

N 1 Hz 2 Hz ------------------------- {3, 1.6*10-7, 5.4*10-10} {4, 4.8*10-8, 3.3*10-11} {5, 2.6*10-8, 3.4*10-12} {6, 2.3*10-8, 6.7*10-12} {7, 2.1*10-8, 2.6*10-12}

Optimized at 1Hz

Courtesy G. Cella

Horizontal

~50 m

G.Cella

2 Independent full simulations in progress

Actuation Noise

Bobina

MagneteVV

-0.2

0.2

V

Lunghezza cavità

V

-0.2

0.2

l/100

Locking

M

GiuntoFlessibile

g

30 mHz

PendoloInvertito

ADC DSP DAC

Actuators

Accelerometers

RESIDUAL SWING < 0.1 mm

CPU

PPC

Motor

Driver

Dual

Port

RAM

DAC-D-

ADC-D-

DSP-D-

DSP-L-

Timing

DOL DAC-L-

DAC-L-

Dual

Port

RAM

ADC-D-

ADC-D-

VME bus

VSB bus 1 VBeX bus 1 VSB bus 2

VBeX bus 2

Superattenuatore

Sensors

Coil Drivers

Motors

Sensors

Sensors

Coil Drivers

Coil Drivers

Position &

Damping

DSP:- 96 bit- 60 MFLOPs

DAC:- 8 Chan.- 20 bit- 500 KHz

ADC:- 8 Chan.- 16 bit

SAR- 200 KHz

Acc. Sens:- 10-9 m/s2

- 0 – 100Hz- f.s. 1g

Control Electronics System

Hierarchical Control

WIND SEAMIRROR

ACTUATION

Tilt

Direct Measurement on the ITF !!

A.Gennai (VIR 029-A09)

Distribution and (its integral) of the maximum of the absolute values of marionettacorrection voltage computed on 200 s-long interval

(all VSR1 run, itf in science mode)

Calm Any

Calm Any

Setting the marionetta actuation range to 2.2 V we “risk” 1% of duty cycle(techical solutions to avoid unlocks available)

Calm Any

Actuation Noise Reduction by

a factor 4 immediatelyavailable !

Reduction factor

3-4 Wind (5%)

7-8 Calm (95%)

Direct Meas. Now

Calm

Wind

AdV

Many other possibility to reduce noise

AdV: SA performance are compliant with AdVboth for passive isolation and actuation noise

ET: Safety margin guarantees present SA attenuation goodalso for the ET project (not too demanding above a few Hz)

Passive isolation compliant above about 3-4 HzOptimization necessary if lower frequency will be investigated

Actuation Noise is the major concern

AdV: Upgrades provide additional safety margin.......

Recent upgrades (each requiring a separate talk)

Gyrolaser: A.Di Virgilio’s group provided an instrument able to monitor ground tilt with the required sensitivity (close to 10-9 rad/Hz1/2) with high duty cycle.

Tiltmeters: The flex-joint solution was killed. A new prototype concevied by A.Giazotto based on a complete different design was assembled (excellent mechanical performance).

Piezo Actuation: The entire electro-mechanical system was assembled by F.Frasconi on SAFE bottom ring and monitored by LVDT. Preliminary tests are very encouraging.

Vertical to Horizontal Coupling: The MSC group measured the coupling factor exciting marionetta in vertical and looking at the itf with a “surprising result” (TBC).