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20 April 2005 D. Verkindt, LAPP, Virgo 1
VIRGO experimentGravitational waves detector
D. Verkindt
20 April 2005 D. Verkindt, LAPP, Virgo 2
First detection of gravitation
20 April 2005 D. Verkindt, LAPP, Virgo 3
Gravitational Waves
20 April 2005 D. Verkindt, LAPP, Virgo 4
First words about gravitational waves
A. Einstein, Preussiche Akademie der Wissenschaften, Sitzungsberichte, p. 688 (1916) A. Einstein, Preussiche Akademie der Wissenschaften, Sitzungsberichte, p. 154-167 (1918)
25 Novembre 1915
20 April 2005 D. Verkindt, LAPP, Virgo 5
An accelerated electric charge produce an electromagnetic wave
How is created a gravitational wave?
An asymmetrically accelerated mass produce a gravitational wave
e-
E
20 April 2005 D. Verkindt, LAPP, Virgo 6
A gravitational wave affects space-time. It modifies the measure of distances.
The visible effects of a gravitational wave
h
xh
h = L / L
L+LL
20 April 2005 D. Verkindt, LAPP, Virgo 7
Undetectable source of GW : you!
h = 10-41 at 1 meter
20 April 2005 D. Verkindt, LAPP, Virgo 8
Strong sources: stars!
Black holesh = 10-20 at 0.02 Mpc
Formation d’un trou noir
Supernovaeh = 10-21 at 1 Mpc
20 April 2005 D. Verkindt, LAPP, Virgo 9
Un signal bien connu théoriquement
Confirmed source: binary coalescence
h(t)
f(t)
Hz
sec
h = 10-21 at 1 Mpc
20 April 2005 D. Verkindt, LAPP, Virgo 10
Binary pulsar 1913+16
- Discovered in 1974 by Hulse and Taylor with Arecibo radio-telescope
- Orbital period : 7.7 hours- Distance: 15000 ly- Coalescence in 300 million years
Hulse Taylor
R.A. Hulse et J.H.Taylor, The Astrophysical Journal, 195, 1975, L51
J.H.Taylor and J.M. Weisberg, « Further experimental tests of relativistic gravity using the binay pulsar 1913+16 », Astrophysical Journal 345, 434-450 (1989)
20 April 2005 D. Verkindt, LAPP, Virgo 11
Challenge of gravitational waves detection
10-10 meters
h = L / L = 10-21
20 April 2005 D. Verkindt, LAPP, Virgo 12
Interferometric detection
IncidentLaser beam
Interference fringes
20 April 2005 D. Verkindt, LAPP, Virgo 13
Dark fringe
Interferometric detection
IncidentLaser beam
20 April 2005 D. Verkindt, LAPP, Virgo 14
Out of dark fringe
L
L
Interferometric detection
IncidentLaser beam
20 April 2005 D. Verkindt, LAPP, Virgo 15
L = h L
< 10-21 3 km
Gravitational Wave
Source: K. Thorne (Ligo)
< 3.10-18 m
Interferometric detection of a gravitational wave
20 April 2005 D. Verkindt, LAPP, Virgo 16
VIRGO experiment
20 April 2005 D. Verkindt, LAPP, Virgo 17
VIRGO experimentFrom NASA world wind software (http://worldwind.arc.nasa.gov)
20 April 2005 D. Verkindt, LAPP, Virgo 18
3 km arms
VIRGO experiment
20 April 2005 D. Verkindt, LAPP, Virgo 19
West
North
VIRGO experiment
20 April 2005 D. Verkindt, LAPP, Virgo 20
Vacuum tanks
VIRGO experiment
20 April 2005 D. Verkindt, LAPP, Virgo 21
Anti-seismic towers
VIRGO experiment
20 April 2005 D. Verkindt, LAPP, Virgo 22
Mirrors
VIRGO experiment
20 April 2005 D. Verkindt, LAPP, Virgo 23
Suspended detection bench
VIRGO experiment
20 April 2005 D. Verkindt, LAPP, Virgo 24
Detection photodiodes
VIRGO experiment
20 April 2005 D. Verkindt, LAPP, Virgo 25
photodiode
laser
Nature is noisy!
VIRGO experiment
laser noise
seismic motion
actuators noise
phase noise
pendulum thermal noise
wires thermal noise
shot noise
20 April 2005 D. Verkindt, LAPP, Virgo 26
Sensibilité du détecteur
VIRGO experiment
20 April 2005 D. Verkindt, LAPP, Virgo 27
septembre 2001 décembre 2001 avril 2002 mai 2002 juillet 2002
First sensitivity of VIRGO interferometer
20 April 2005 D. Verkindt, LAPP, Virgo 28
run E0 (september 2001) run E4 (july 2002)
E 0
VIRGO experiment
20 April 2005 D. Verkindt, LAPP, Virgo 29
VIRGO experiment
Control loops
From R. Flaminio
20 April 2005 D. Verkindt, LAPP, Virgo 30
VIRGO experiment
Locking scheme of recombined interferometer
Common Mode control loop (low
frequency)
Laser0
B2
B1_ACp
+
-
Differential Mode control loop
BS
B2 phase
Reference cavity
+
+
B2 quad
LW
LN
BS angular control (Sc_BS_txCmir)
from R. Gouaty
20 April 2005 D. Verkindt, LAPP, Virgo 31
VIRGO experiment
Laser0
B2_3f ACp B1
ACp
+
-
Differential mode
B5
PR
Laser frequency control loop (SSFS)
B5_ACp
B5_ACq
BS
Locking scheme of recycled interferometer B1_ACp used to control the Differential Mode
B5_ACq used to control the Beam Splitter (Michelson mode)
B2_3f_ACp used to control the Recycling cavity length (PR)
B5_ACp used to control laser frequency (Common Mode)
from R. Gouaty
20 April 2005 D. Verkindt, LAPP, Virgo 32
VIRGO experiment
from R. Gouaty
20 April 2005 D. Verkindt, LAPP, Virgo 33
C1: Sept 2003 C4: juil 2004 C5: dec 2005
Current sensitivity of VIRGO interferometer
20 April 2005 D. Verkindt, LAPP, Virgo 34
VIRGO experiment
20 April 2005 D. Verkindt, LAPP, Virgo 35
Other GW interferometric detectors
20 April 2005 D. Verkindt, LAPP, Virgo 36
4 km600 m 3 km
300 m
20 April 2005 D. Verkindt, LAPP, Virgo 37
LIGO experiment
LIGO Hanford Observatory (LHO)H1 : 4 km armsH2 : 2 km arms
LIGO Livingston Observatory (LLO)L1 : 4 km arms
10 ms
20 April 2005 D. Verkindt, LAPP, Virgo 38
LIGO experiment
Livingston
Hanford
20 April 2005 D. Verkindt, LAPP, Virgo 39
Current sensitivy of LIGO interferometers
20 April 2005 D. Verkindt, LAPP, Virgo 40
New telescopes: giant interferometers 3 km long…listening to the sky
20 April 2005 D. Verkindt, LAPP, Virgo 41
LISA project
Interferometer in space
The Future (…2014 ?)
20 April 2005 D. Verkindt, LAPP, Virgo 42
A new way to see the Universe
Crabe Nebula
20 April 2005 D. Verkindt, LAPP, Virgo 43
Source: A Weinstein (Ligo)
Ondes Gravitationnelles
?
A new way to see the Universe
20 April 2005 D. Verkindt, LAPP, Virgo 44
Gravitational waves a new window on the Universe…
More informations
lapp.in2p3.fr/virgowww.virgo.infn.itwww.ligo.caltech.edu