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Present Superatttenuator performance vs. AdV & ET Requirements S.Braccini for Virgo Suspension group. Passive Attenuation. 2 Hz. Long Pendula. Ground. Resonances. f -2N. Transmission. Frequency (Hz). Soft Springs. Mirror. Magnetic Antisprings. 8 m. Blade Springs.

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present superatttenuator performance vs adv et requirements s braccini for virgo suspension group

PresentSuperatttenuator performance vs. AdV & ET RequirementsS.Braccini for Virgo Suspension group

slide4
2 Hz

Long Pendula

Ground

Resonances

f-2N

Transmission

Frequency (Hz)

Soft Springs

Mirror

slide5
Magnetic

Antisprings

8 m

Blade Springs

slide6
Rumore Termico

Ground Seismic Noise

Mirror Seismic Noise

slide7
SA design

e freccette

Filter Chain TF measurements

(without Pre-Isolator !)

slide8
SA design

e freccette

CITF Measurements

around 2, 4, 9 Hz

@ 4.1 Hz

< 6 ×10e-8

slide9
SA design

e freccette

CITF Measurements

around 2, 4, 9 Hz

@ 2.25 Hz

5 ×10e-6

slide10
Thermal Noise

Measured

Upper Limit

slide13
TFmax = DL(f) /(LSD Ground Seismic Noise)

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

slide16
TFmax = DL(f) /(LSD Under-Ground Seismic Noise)

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

(Duzel Mine much better)

slide19
TFmax = DL(f) /(LSD Ground Seismic Noise)

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

slide21
High Sens Range

Larger stability

allows longer measurements

slide22
Displacement (m .Hz-1/2)

Transfer Function < 10-10

SA design

e freccette

Top

frequency (Hz)

Mirror

slide23
TF < 1.7 x 10-12

TOP

1.2 x 10-6m Hz-1/2

MIRROR

Stressed

Measurement

T = 41943 s

High Sens Range

2 x 10-18m Hz-1/2

slide25
AdV

ET-Xylophone

1.26 x 10-11

+ Pre-Isolator

slide26
SA design

e freccette

SA design

e freccette

Possible Bypass

X-excitation

slide27
X - Excitation Results

Bypass

Indication ?

slide28
Red = Line Detected

Blue = Line Not Detected

Purple = Upper Limit

not useful (too large)

slide29
Upper Limit

Detected

53

113

AdV

ET-Xylophone

IP Guarantees for this !

Already compliant for ET

(Remind that we are speaking of “Upper Limits”

Without Pre-Isolator (Just filter chain !)

slide30
Vertical TF measurements

(Coupling included in the measurement)

slide32
Vertical Upper Limit

Vertical Detected

60

AdV

ET-Xylophone

F0 Guarantees for this

UPPER LIMIT (!) compliant for ET

Without Filter Zero (Just filter chain !)

slide33
Preisolator makes safety

margin wide in AdV

slide35
HORIZONTAL

@ 2.25 Hz

5 ×10e-6

Remarkable Attenuation also at 2.25 Hz

slide36
VERTICAL

@ 2.25 Hz

1.5 ×10e-6

Remarkable Attenuation also at 2.25 Hz

slide37
Stage by Stage Measurement (and Model)

TF

Model

Meas.

No

Maybe

Yes

2

3

4

f

slide38
ET Design Programme

Cut-off 3-4 Hz  No Design Study

Cut-off 1-2 Hz  Design Study

SCIENCE CASE & NEWTONIAN NOISE

TO BE DISCUSSED AT ERICE MEETING

slide39
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

~50 m

Horizontal

G.Cella

slide42
V

V

V

V

0.2

0.2

Magnet

Coil

-0.2

-0.2

CavityLength

l/100

Locking

slide44
M

g

Inverted

Pendulum

Flex Joint

30 mHz

slide45
Accelerometers

DSP

DAC

Actuators

ADC

slide46
Motors

Sensors

Coil Drivers

Sensors

Coil Drivers

Sensors

Coil Drivers

Superattenuatore

  • Acc. Sens:
  • -10-9 m/s2
  • 0 – 100Hz
  • f.s. 1g

Control Electronics System

Position

&

Damping

  • DSP:
  • 96 bit
  • - 60 MFLOPs
  • DAC:
  • -8 Chan.
  • 20 bit
  • 500 KHz
  • ADC:
  • -8 Chan.
  • 16 bit SAR
  • - 200 KHz
slide48
Accelerometers

RESIDUAL SWING < 0.1 mm

DSP

DAC

Actuators

ADC

slide51
Direct Measurement on the ITF !!

A.Gennai (VIR 029-A09)

slide52
Distribution and (its integral) of the maximum of the absolute values of marionetta

correction voltage computed on 200 s-long interval

(all VSR1 run, itf in science mode)

slide53
Any

Calm

slide54
Any

Calm

slide55
Actuation Noise

Reduction by

a factor 4

immediately

available !

Any

Calm

Setting the marionetta actuation range to 2.2 V

we “risk” 1% of duty cycle

slide56
Reduction factor

3-4 Wind (5%)

7-8 Calm (95%)

Calm

Wind

AdV

Direct Meas. Now

Many other possibility to reduce noise

slide58
2009-10

SAFE

Resp: F.Frasconi

slide60
Recentupgrades

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).

slide61
Conclusions

AdV: SA performance are compliant with AdV

both for passive isolation and actuation noise

ET: Present SA attenuationgoodalso for the ET project

(not too demanding above a few Hz)

Passive isolation compliant above about 3-4 Hz

Design Studynecessary if lower frequency will be investigated

Actuation Noise is the major concern

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