Pipe baffle shaking tests

S.Braccini, C.Bradaschia, I.Fiori, F.Paoletti

Mid Baffle First Baffle

1410 m West

No DAQ

hammershake

quiet

MID BAFFLEEXCITATION

NO EFFECTON DARK FRINGE

Mid baffle seismic noise is not now limiting the sensitivity

(Noise upper limit can be set)

)(~)(~

)(~

)(~

0 fxfx

fhfh

Excitation

ySensitivitNoise

)(~)(~)(

~

)(~)()(~

00 fxfx

fhfxfTFfh

Excitation

ySensitivitUpperLimitNoise

)(~)(~

0 fxKfhNoise Constant TF

K 4 x 10-15 m -1

)(~104)(~

015 fxfhNoise

hammershake

quiet

)40(~)40(~

0 HzxKHzhNoise 6 x 10 -22

1.5 x 10 -7

Upper limit by mid baffle for any constant TF process

Adv Sensitivity

……. Another step…Beyond single baffle

h ( ƒ ) = - - - - - - 1 2

( 2 ) - 5 / 4

g 1 / 2

L - 1 / 2 b ' - 3 / 2

k = 1

n b a f f l e s - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

x k ( 1 - x k )

x k 2 + ( 1 - x k )

2 F ( m )

1 / 2

( ƒ )

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.00.00

0.10

0.20

0.30

0.40

0.50

0.60e = 0

e=0.05

e=0.1

e=0.2

x

weight of baffles vs location for various offsets of the optical axis

Upper limit for diffraction on all baffles

AdV Sensitivity

Upper Limit

Theory with detected seismic noise

We know the weight of each baffle with respect to the central one(dominant) where we have just set un upper limit

OTHER REMARKS

Same seismic noise on all pipe mid baffles

No special effect on a single baffle

North Pipe could be different

A) No hypothesis Mid baffle seismic noise does not affect presentsensitivity (but only scarce upper limit can be set)

B) Flat TF hypothesis Good upper limit for seismic noise by Mid baffle

CONCLUSIONS FROM MID BAFFLE TEST

C) Extension to all baffles(Theoretical Model and Assumptions)

Upper limit for diffraction on all baffles

AdV Sensitivity

Upper Limit

Theory with detected seismic noise

Gives us an upper limit for the entire“diffraction noise”

It is easy (but not urgent)to improve upper limit…

Pipe baffle shaking tests

S.Braccini, C.Bradaschia, I.Fiori, F.Paoletti

Mid Baffle First Baffle

hammer

shake

quiet

Excitation

Excitation

No Effect on DF

Present “Safety Margin” (no hypothesis)

First Baffle Upper Limit (Flat TF hypothesis)

CONCLUSIONS FROM FIRST BAFFLE TEST

Conceptually identical to the Mid Baffle ones (but different seismic noise)

A) No hypothesis Mid baffle seismic noise does not affect presentsensitivity (but only scarce upper limit can be set)

B) Flat TF hypothesis Good upper limit for seismic noise by Mid baffle

C) Extension to all baffles(Theoretical Model and assumptions)

Uncoherent sums with different seismic noise (all baffle weight 1)