A b o u t g r a v i t a t i o n a l w a v e d - - PowerPoint PPT Presentation
A b o u t g r a v i t a t i o n a l w a v e d e t e c t o r s A b o u t g r a v i t a t i o n a l w a v e d e t e c t o r s L o c R o l l a n d L a b o r a t o i r
L
c R
l a n d
L a b
a t
r e d ’ A n n e c y d e P h y s i q u e d e s P a r t i c u l e s
Université Grenoble-Alpes Saint Martin d’Hères December 5th 2018
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R e l i c r a d i a t i
C
m i c s t r i n g s S u p e r m a s s i v e b i n a r y b l a c k h
e b i n a r i e s B i n a r y m e r g e r s S u p e r n
a e E x t r e m e m a s s r a t i
i n a r i e s B i n a r i e s
b l a c k h
e s a n d n e u t r
s t a r s R
a t i n g n e u t r
s t a r s
3
4
F
G W1 7 8 1 4 , fj r s t V i r g
e t e c t e d e v e n t : h = 5 x 1
2
→ δ L = ± . 8 x 1
8
m time
h(t): a m p l i t u d e
t h e G W ( h h a s n
i m e n s i
) M a s s e s i n m
i
G r a v i t a t i
a l w a v e S p a c e
i m e d e f
m a t i
5
✔ R
e j e c t i
s p u r i
s l
a l n
s e ( c
n c i d e n c e ) → b e t t e r s e n s i t i v i t y
✔ S
r c e l
a l i s a t i
( t r i a n g u l a t i
) → a s t r
y
✔ Wa
v e p
a r i z a t i
N e t w
k w
k i n g a s a s i n g l e d e t e c t
s i n c e 2 7
6
7
E q u i v a l e n t s i z e
V i r g
e a m We d
m e a s u r e n i c e f r i n g e i m a g e s !
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9
10
Input beam Sensor
Power recycling cavity 3-km Fabry-Perot cavities
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F a b r y
e r
c a v i t i e s ( 3 k m , fj n e s s e 4 5 ) O u t p u t
e
l e a n e r c a v i t i e s ( ~ 7 c m ) I n p u t
e
l e a n e r c a v i t y ( ~ 1 m ) P
e r R e c y c l i n g a n d S i g n a l R e c y c l i n g C a v i t i e s
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Input beam Photodiode
1 4
Photodiode Photodiode
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Higher order modes in the output beam
(due to interferometer imperfections)
Gaussian beam,
the one sensitive to gravitational waves
Main beam Sidebands
e l t i e r c e l l
i e z
c t u a t
2 bow-tie cavities in series
15
l
k p r e c i s i
: f e w 1
2
m l i m i t e d b y t h e r m
e f r a c t i v e n
s e ( 4
H z ) C a v i t y l e n g t h n
s e P h
i
e p
e r v a r i a t i
s N
s e i n h ( t ) s e n s i t i v i t y
e g l i g i b l e
i s h i n g
r e fm e c t i v e s u r f a c e s
e m a t c h i n g a n d a l i g n m e n t
e m a t c h i n g , p
a r i z a t i
, a l i g n m e n t
17 cNm 13 cNm 4 cNm
length Transmitted power Airy peak
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➢ Reducing quantum noise ➢ Reducing thermal noise ➢ Reduction of technical noise
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18
Wo r k i n g p
n t c l
e t
d a r k f r i n g e S i g n a l r e l a t e d t
h a s e
s e t → fm u c t u a t i
s
t h e p h a s e P h
s h
n
s e → fm u c t u a t i
s
t h e m i r r
p
i t i
s R a d i a t i
p r e s s u r e n
s e V a c u u m fm u c t u a t i
s
phase amplitude Phase fluctuation Laser power Amplitude fluctuation x Laser power
19 Photon shot noise Quatum noise Radiation pressure noise
Fluctuation of differential length Fluctuation of measured power Fluctuation of measured power
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continuous 200 W laser, stable monomode beam (TEM00), 1064 nm frequency pre-stabilisation 1 Hz linewidth low power noise (~10-9 /sqrt(Hz) in AdV bandwidth) low beam jitter <10-11 rad/sqrt(Hz) at 10 Hz
1 W seed, amplified to 100 or 200 W
➔ Two 100 W laser with coherence addition? ➔ A direct 200 W laser?
→ need of thermal compensation system
coupling of laser high order modes with mirror modes
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→ d e c r e a s e p h
s h
n
s e b u t i n c r e a s e r a d i a t i
p r e s s u r e n
s e V a c u u m fm u c t u a t i
s
phase amplitude
I n s t a l l e d i n V i r g
n d L I G O C
m i s s i
i n g
n g ( c u r r e n t l y . 5 d B i m p r
e m e n t ) → c
s t r a i n t s
t i c a l l
s e s , b e a m m a t c h i n g a n d a l i g n m e n t , . . .
22
→ d e c r e a s e p h
s h
n
s e A N D r a d i a t i
p r e s s u r e n
s e V a c u u m fm u c t u a t i
s
phase amplitude
V a c u u m fm u c t u a t i
s
phase amplitude
O n
n g d e s i g n i n V i r g
n e e d a fj l t e r c a v i t y
~ 3 m , w i t h fj n e s s e ~ 1 → s t r
g c
s t r a i n t s
t i c a l l
s e s , b e a m m a t c h i n g a n d a l i g n m e n t , … ( s u s p e n d e d i n v a c u u m
t i c a l b e n c h e s )
23
24
→ d i s s i p a t i
e n e r g y t h r
g h e x c i t a t i
t h e m a c r
c
i c m
e s
t h e m i r r
We w a n t h i g h q u a l i t y f a c t
s Q t
c e n t r a t e a l l t h e n
s e i n a s m a l l f r e q u e n c y b a n d
Pendulum mode f < 40 Hz “Mirror” mode f> few kHz “Violin” modes f > 40 Hz
Fluctuation of differential length Fluctuation of measured power Thermal fluctuation of mirror surface position
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26
→ talk by J. Degallaix!
40 kg mirrors of Advanced Virgo 35 cm diameter, 40 cm width
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( c u r r e n t l y 5
c m r a d i u s
m i r r
s )
→ l a r g e r m i r r
s ( a n d h e a v i e r ) → m e c h a n i c a l c
s t r a i n t s
m i r r
s u s p e n s i
s → l a r g e r s i z e
c
t i n g → u p g r a d e
t i c a l b e n c h e s t
e t e c t
t p u t b e a m s → u s e h i g h
d e r m
e s i n s t e a d
T E M G a u s s i a n m
e ?
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29
Array of seismometers and microphones Building model + real-time monitoring of Newtonian noise Noise subtracted from h(t)
(contribution at low frequency)
Newtonian noise cancellation → R&D for “smart infrastructure”
(low noise air conditioning, fans, ...)
Reduction of Newtonian noise
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Optical benches suspended and placed in vacuum
limited number of cables (power, data) space and load constraints, thermal constraints bench position control →integrated electronics
Better optics (polishing) and beam dumps New baffles to absorb light and ghost beams
in the tubes and towers, around the mirrors
Light recombination in the interferometer Scattered light + Vibrated parts (seismic/acoustic) Phase noise in the detected beam Reduce the coupling with seismic/acoustic noise Reducing the amount of scattered light
Peaks and structures in the sensitivity curve
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→ talk by D. Estevez !
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→ c
l e s c e n c e
s u p e r m a s s i v e b l a c k h
e s , . . .
→ m
i t
i n g
~ 2 m i l l i s e c
d p u l s a r s → p u l s e t i m i n g d e v i a t i
~ 1 ’ s n s
e r a y e a r
s y s t e m a t i c u n c e r t a i n t i e s t
e r e d u c e d !
34
Einstein Telescope Virgo LIGO Pulsar Timing Arrays Cosmological Microwave Background Cosmic Explorer LISA
→ talk by R. Bonnand!