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VIRGO Superattenuators in next generation detectors S.Braccini, INFN-Pisa on behalf of the Virgo Collaboration. 1) SAT Seismic Isolation: Present & Future. 2) SAT “Passive Control”. 3) SAT Mechanical Glitch Noise. 2. Superattenuator. Magnetic Anti-Spring. 8 m. Blade Springs. 3. 2 Hz.

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VIRGO Superattenuators in next generation detectors S.Braccini, INFN-Pisa

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Virgo superattenuators in next generation detectors s braccini infn pisa

VIRGO Superattenuators

in next generation detectors

S.Braccini, INFN-Pisa

on behalf of the Virgo Collaboration


Virgo superattenuators in next generation detectors s braccini infn pisa

1) SAT Seismic Isolation: Present & Future

2) SAT “Passive Control”

3) SAT Mechanical Glitch Noise

2


Virgo superattenuators in next generation detectors s braccini infn pisa

Superattenuator

Magnetic Anti-Spring

8 m

Blade Springs

3


Virgo superattenuators in next generation detectors s braccini infn pisa

2 Hz

Ground

Resonances

f-2N

Transmisson

Frequency (Hz)

Long Pendula

Soft Springs

Mirror

4


Virgo superattenuators in next generation detectors s braccini infn pisa

2 Hz

Resonances

f-2N

Frequency (Hz)

Large Inertia

Thin Wires

5


Virgo superattenuators in next generation detectors s braccini infn pisa

Stage by Stage Measurement

Thermal Noise

Ground Seismic Noise

Mirror Residual Seismic Noise

6


Virgo superattenuators in next generation detectors s braccini infn pisa

DirectMeasurement

SA design

e freccette

7


Virgo superattenuators in next generation detectors s braccini infn pisa

TF < 1.7 x 10-12

TOP

1.2 x 10-6m Hz-1/2

MIRROR

2 x 10-18m Hz-1/2

8


Virgo superattenuators in next generation detectors s braccini infn pisa

TF = 1.26 x 10-11

TOP

MIRROR

!

!

9


Virgo superattenuators in next generation detectors s braccini infn pisa

Upper limitHoriz

Upper limit Vertical

10


Virgo superattenuators in next generation detectors s braccini infn pisa

Upper limitHoriz

Upper limit Vertical

11


Virgo superattenuators in next generation detectors s braccini infn pisa

SA design

e freccette

SA design

e freccette

X-Excitation

Experiment

Bypass ?

12


Virgo superattenuators in next generation detectors s braccini infn pisa

AdV - Seismic Isolation OK

ET - Reduction of low frequency cut-off

13


Virgo superattenuators in next generation detectors s braccini infn pisa

Stage by Stage TF

Crossing expected @ 2.5-3 Hz

14


Virgo superattenuators in next generation detectors s braccini infn pisa

Confirmed by direct measurements

Horiz

Vertical

ET

ETx

Horizontal seismic noise dominant

15


Virgo superattenuators in next generation detectors s braccini infn pisa

PRESENT CROSS-OVER

ET

ETx

16


Virgo superattenuators in next generation detectors s braccini infn pisa

Change both number of filters and their distance

(thus varying the total length)

HORIZONTAL

TF

17


Virgo superattenuators in next generation detectors s braccini infn pisa

HORIZONTAL

5 filters - 15 m

7 filters - 16 m

6 filters - 17 m

6 filters - 14 m

TF

1.8 Hz

18


Virgo superattenuators in next generation detectors s braccini infn pisa

Upper limitHoriz

Upper limit Vertical

Vertical Attenuation

19


Virgo superattenuators in next generation detectors s braccini infn pisa

6 Filters (as now)

TF

FILTER @ 310 mHz


Virgo superattenuators in next generation detectors s braccini infn pisa

CONCLUSION

3rd GENERATION: Use identical technology

with cross-over below 2 Hz

Present SA extension 9 17 m

(1.8 Hz conservative cross-over)

21


Virgo superattenuators in next generation detectors s braccini infn pisa

1) Seismic Isolation: Present & Future

2) “Passive Control”

3) Mechanical Glitch Noise

22


Virgo superattenuators in next generation detectors s braccini infn pisa

several microns

mirror swing

23


Virgo superattenuators in next generation detectors s braccini infn pisa

Accelerometers

DSP

DAC

Actuators

ADC

24


Virgo superattenuators in next generation detectors s braccini infn pisa

Swing reduction by ID

+

ultra-low freq. passive attenuation

8 m

25


Virgo superattenuators in next generation detectors s braccini infn pisa

Alignment without

affecting mirror swing

(Payload ad hoc design)

1) Intrinsically diagonalized (Easy control)

2) “Nothing happens” in the off-diagonal world

26


Virgo superattenuators in next generation detectors s braccini infn pisa

“Passive strategy” in prealignment (qy)

27


Virgo superattenuators in next generation detectors s braccini infn pisa

“Passive strategy” in prealignment (qx)

28


Virgo superattenuators in next generation detectors s braccini infn pisa

Alignment

transparent for SA

8 m

29


Virgo superattenuators in next generation detectors s braccini infn pisa

Acquire the locking with no recoil

30


Virgo superattenuators in next generation detectors s braccini infn pisa

Acquire the locking with negligible recoil

31


Virgo superattenuators in next generation detectors s braccini infn pisa

Lock Acquisition

transparent for SAT

8 m


Virgo superattenuators in next generation detectors s braccini infn pisa

1) Longitudinal swing fraction of mm/s

2) Prealign mirror (fract. of mrads)

(not affecting 1)

3) Lock acquisition

(not affecting 1 - 2)

8 m

4) Reallocation & Tidal Control

(not affecting 1 - 2 - 3)

Residual Swing

LONGITUDINAL: around 100 nm pk pk

ANGLES: fractions of mrad pk pk


Virgo superattenuators in next generation detectors s braccini infn pisa

500 nrad

RESIDUAL (OPEN LOOP) DISPLACEMENTS

100 nm

SMALL LOCKING & ALIGNMENT CORRECTIONS  LOW NOISE

HIGH ACCURACY: 10 nrads on PR,a few nrads on test masses


Virgo superattenuators in next generation detectors s braccini infn pisa

RM

AdV

Marionetta

CONTROL NOISE - OK for AdV

35


Virgo superattenuators in next generation detectors s braccini infn pisa

1) Seismic Isolation: Present & Future

2) “Passive Control”

3) Mechanical Glitch Noise

36


Virgo superattenuators in next generation detectors s braccini infn pisa

Self-organized criticality dynamics

of dislocations induces a mechanical

shot-noise force (1/f)

37


Virgo superattenuators in next generation detectors s braccini infn pisa

Potential problem

in last filter(s)

of the chain

38


Virgo superattenuators in next generation detectors s braccini infn pisa

3 VERTICAL MODES

F7 -Blades

40 Hz

Marionetta

15 Hz

7 Hz

Reference

Mass

Mirror

39


Virgo superattenuators in next generation detectors s braccini infn pisa

MODES VISIBLE IN DARK FRINGE

Displacement Strain (m Hz^-1/2)

40

Freq (Hz)


Virgo superattenuators in next generation detectors s braccini infn pisa

TF MEASUREMENT

Blades

Mar

RM

Mir

41


Virgo superattenuators in next generation detectors s braccini infn pisa

TF MEASUREMENT

Mirror-Beam Displacement (m) / Vertical Force (N)

7 Hz

15 Hz

40 Hz

Freq (Hz)

42


Virgo superattenuators in next generation detectors s braccini infn pisa

VERTICAL FORCE UPPER LIMIT

z(w) = TF(w) x Fv(w)

7 Hz

40 Hz

Fv_max (w) = z(w) / TF(w)

43


Virgo superattenuators in next generation detectors s braccini infn pisa

VERTICAL FORCE UPPER LIMIT

Vertical Force (Upper Limit – N/Hz1/2)

Freq (Hz)

44


Virgo superattenuators in next generation detectors s braccini infn pisa

VERTICAL FORCE UPPER LIMIT

Vertical Force (Upper Limit – N/Hz1/2)

Freq (Hz)

45


Virgo superattenuators in next generation detectors s braccini infn pisa

VERTICAL FORCE UPPER LIMIT

Vertical Force (Upper Limit – N/Hz1/2)

X TF

Freq (Hz)

46


Virgo superattenuators in next generation detectors s braccini infn pisa

h(f)

Virgo

AdV

1/f noise

upper limit

47


Virgo superattenuators in next generation detectors s braccini infn pisa

START PARENTHESIS

(just for a betterunderstanding)


Virgo superattenuators in next generation detectors s braccini infn pisa

F

Vertical Force on Marionetta  MirrorDisplacementalongbeam

z


Virgo superattenuators in next generation detectors s braccini infn pisa

Closedparenthesis

h(f)

Virgo

AdV

1/f noise

upper limit


Virgo superattenuators in next generation detectors s braccini infn pisa

Peaks dominated by DAC noise

More stringent upper limits

could be set in VSR3

Model Dependent Approach……

51


Virgo superattenuators in next generation detectors s braccini infn pisa

Marchesoni et al.

Step

(mean)

Rate

52


Virgo superattenuators in next generation detectors s braccini infn pisa

15 Hz peak amplitude evolution

rms

Time s

53


Virgo superattenuators in next generation detectors s braccini infn pisa

Distribution of the differences

54


Virgo superattenuators in next generation detectors s braccini infn pisa

Distribution of the differences

1 Hz

0.1 Hz

l> 0.1 - 1 Hz

55


Virgo superattenuators in next generation detectors s braccini infn pisa

Virgo

AdV

Upper Limit

A FEW UNITS

Stringent Upper Limits (AdV OK)

56


Virgo superattenuators in next generation detectors s braccini infn pisa

Conclusions

Superattenuators validated for 2° generation

Virgo+ Monolithic Test

Passive Attenuation

Microglitchness

Control Performance

57


Virgo superattenuators in next generation detectors s braccini infn pisa

Conclusions (3° generation)

Superattenuators validated for 2° generation

9 17 m

(a must also for cross-couplings)

Passive Attenuation

Microglitchness

Control Strategy

More stringent upper limits

(Last stage(s) only)

1) “Passive” strategy decisive

2) Extend hierarchical stages

3) New electronics

(SAFE)

58


Virgo superattenuators in next generation detectors s braccini infn pisa

A residual problem

59


Virgo superattenuators in next generation detectors s braccini infn pisa

The wind problem

MIRRORACTUATION

WIND

SEA

60


Virgo superattenuators in next generation detectors s braccini infn pisa

Tilt

61


Virgo superattenuators in next generation detectors s braccini infn pisa

Tiltmeters R&D

10-8-10-9 rad Hz-1/2 @ 30 mHz

62


Virgo superattenuators in next generation detectors s braccini infn pisa

SAFE Prototype

63


Virgo superattenuators in next generation detectors s braccini infn pisa

THE END

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