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