Ground-based GW detectors: status of experiments and ...€¦ · •2007: CLIO (cryo detector),...

C.N.ManUniv. Nice-Sophia-Antipolis, CNRS, Observatoire de Cote d’Azur

Ground-based GW detectors:

status of experiments and collaborations

�A short history

�GW & how to detect them with interferometry

�What are their sensitivities to GW and to noises

�The network of detectors in the world and their peculiarities

�Status of the detectors and combined observations

�Advanced detectors

�to improve sensitivity in LF range with Monolithic suspension

�Astrophysics with these detectors (just a flavor)

�Summary

1C.N.Man - Colloque Kick-off, les Houches, 20-22/10/09

Prehistory of GREX

� More than 25 years ago, GREX had an ancestor

� Informal meetings triggered by Philippe Tourrenc � French scientists � detection of GW

� Meetings in ENS or IHP with Ch.Bordé, C.Cohen-Tannoudji, T.Damour, …

ExperimentalistsMathematicians

Thanks to that initiative and to those people, Virgo has been supported by CNRS and exists today

This “GREX” community meets regularly and is growing up every day .

GREX = Gravitation Expérimentale


GW itf detection brief story

•1973 Noise studies and initial design: Rainer Weiss (M.I.T)

•1975 Prototypes in Glasgow and Garching

•1980’s Recycling interferometers: Ron Drever (Glasgow and Caltech)

•1982 First activities in France and Italy (optics, seismic isolation)

•1986-1989 Proposals for kilometric projects

•1990-1994 Construction starts in USA and Italy

•2000-2004 Commissioning

•2007: First coincidence runs of initial detectors

•2007: CLIO (cryo detector), design of advanced detectors matured

•2008: First upgrades Virgo+, enhanced LIGO

•2009: more advanced detectors Europe, Australia


Gravitational waves

Strain sensitivity : h # 10-21 to 10-23/√Hz

Emitted in extreme conditions of density and speed


GW sources

Continuous wave sources: rapid rotating neutron star, coalescing of massive binaries

Stochastic background: astrophysical , cosmological (BB)

Bursts: neutron stars or black holes

«chirp»Ex of wave emitted by 2 coalescing NS


Detecting GW with laser interferometry

Michelson’s transmission on dark fringe

GW shifts dark fringe interference of the order of 10-11 to 10-12rd/√Hz


Typical optical configuration

Power recycling to reach the kW level on the BS

Fabry-Perot in each arm to have longer arm length

Typical control system

AC detection to avoid VLF noise of the laser source


Noise limitations => sensitivity


World-wide network

TAMA600 m

300 m4 & 2 km

4 km

AIGO

3 km

+ Ultra cryo resonant detectors (Italy) and LISA to come….

TAMA

AIGO


3 kilometric detectors + a few hundred meters prototype

TAMA 300 (m)

Located at N.A.O near TokyoProject started in 1995

Best world sensitivity between 2000-2002 (first hundred meters itf to run)

Fabry-Perot Michelson config. with power recycling similar to LIGO and Virgo


TAMA sensitivity

recognized need for better seismic isolation = new development with LIGO based on Virgo’s earlier concept

Performance achieved


CLIO (100m proto in Kamioka mine)

20 °K


AIGO (australian internl GW observatory)


AIGO site


World-wide network

TAMA600 m

300 m4 & 2 km

4 km

AIGO

3 km


GEO 600 (m)

Position of SR mirror changes

frequency response

Located near Hannover

Simple Michelson, no Fabry-Perot, the only one today with signal recycling


World-wide network

TAMA600 m

300 m4 & 2 km

4 km

AIGO

3 km


2 x LIGO (laser itf gw

observatory)


•a self-governing collaboration seeking to detect GW

• works toward this goal through R&D, commissioning and exploitation of the

detectors.

•Founded in 1997, the LSC is currently > 700 members from > 50 institutions

and 12-13 countries.

•carries out the science of the LIGO Observatories, in Hanford, Livingston, +

GEO600

Nov 2007, Virgo and LSC signed agreement to jointly analyse all future

common runs

LSC community @ LIGO labs


Combined observations LIGO-Virgo-GEO

First common run in May 2007, 5 months of data (LIGO S5, Virgo VSR1)

Virgo


Results

of the initial detectors

World-wide network

TAMA600 m

300 m4 & 2 km

4 km

AIGO

3 km


Virgo

•3 kms arms, Fabry-Perot Michelson

with power recycling

•French-Italian detector + groups in

Poland, Netherlands, Hungary

•Best seismic isolation => best in

range < 80 Hz


The Super-attenuator(SA) is a multi-stage seismic attenuator with an inverted pendulum as pre-isolator

Expected attenuation @10 Hz > 1014

1014 !

World best LF sensitivity

Seismic Isolation of Virgo


• Material: low loss fused silica (special Virgo)• Dimension: 35 cm diameter, 10 cm thick• Mass: ~ 21 Kg

• Substrate absorption: 1 ppm/cm

• Coating losses:

Virgo detection capability

C.N.Man - Colloque Kick-off, les Houches, 20-22/10/0925

Compared sensitivities of

LIGO S6-Virgo VSR2 (17/10/09)

Virgo


Advanced interferometers

Sensitivity goal better than initial ones by a factor 10 with new technologies:

•Dual recycled interferometer (power and signal recyclings)

•42 kg mirrors and Fabry-Perot of finesse 800 (instead of 50 in Virgo)

•Larger beam spot on mirrors to lower thermal noise

•200W laser power at input

•Thermal compensation of mirrors heating by CO2 laser & ring heater

•Monolithic suspension in the last stage

•Detection photodiodes under vacuum

Adv Virgo plans to be ready to take data at the same time as Adv LIGO (2014)

(Adv LIGO approved by NSB on March 2008 for a 7 years project of 205 M$)


� Ultra high vacuum at low cost: lower outgassing rate, welding, …

� Seismic isolation: need >= 1012 at 10 Hz (all DoF)

� Laser: very low noise (Freq &Power), MTBF, high power, beam stability

� Optics: ultra low losses (substrates and coatings)

� Optical materials: high Q for low thermal noise

� Monolithic suspensions (silicate bonding)

� Real time control system: > 100 servo loops, many DoF, very low noise from

mHz to MHz

� Data processing: high rate (6MB/s), fast processing (Tflop)

Key technologies shortlist


AdV sensitivity vs Finesse

tIN 0.001 0.003 0.005 0.007 0.01

Finesse 5844 2043 1238 888 623

G 3.6 10 17 23 33

PBS 447 1277 2103 2927 4156

BNS 92 128 126 121 112

BBH 328 597 770 859 898


Advanced detectors’ goal sensitivity

AdV + no SR

AdV with SR


Some thoughts on the existing detectors

Virgo has the best sensitivity in the LF range thanks to the performant

suspension => could detect GW emitted by pulsars in the LF range by

integrating signal over months (from 10 Hz).

For Advanced Virgo, it’s worth adding monolithic suspension to lower

suspension thermal noise.

LIGO has two/three detectors => could make all the first detections on their

own if GW signal strong enough in their sensitivity range ( 50 Hz-2 kHz)

An agreement has been made in order not to stop all the detectors at the

same time in case something happens near our galaxy: ASTRO-WATCH


Today’s Virgo performances Test masses = 3 10-15 rad/sqrt(Hz)

Residual angular motion of Test masses in absence of rad press= 5x10-18 rad/√Hz at 10 Hz

Other recycling mirrors and BS = 10-14 rad/√Hz - 10-15 rad/√Hz

Decentering < 1mm

Adv: Test-mass residual motion requirements

A factor 1000 in LF to gain by taking care of ….


F7 Coil

Pots

The role of the Last Suspension Stage is to compensate the residual seismic noise +to steer the mirrors to maintain the relative position of the interferometer mirrors.

Last stage of the Virgo suspension


Advanced Virgo payload


Marionette (Virgo+ like, monolithic suspensions compliant~ 100 kg mass)

Recoil Mass (Virgo+ like, monolithic suspensions compliant,~ 42 kg mass)

Mirror: 350 mm ø, 200 mm thickness, 42 kg

Marionette Recoil Mass (MRM): R&D•Marionette steering•No coil pots and filter 7 legs•Allows to suspend mirrors with diameter > 370 mm•Mass ~ 85 kg (filter 7 legs)

Total Payload Mass ~ 180 kg

AdV sensitivity vs Fiber geometry

� The ribbon choice reduced considerably the contribution of susp. th. noise, but…

� The benefits on the sensitivity are limited by radiation pressure, newtonian and CONTROL NOISE

fiber fiber fiber fiber

geometrygeometrygeometrygeometry

cylindricalcylindricalcylindricalcylindrical ribbonribbonribbonribbon

FinesseFinesseFinesseFinesse 885

GGGG 23.5

PPPPBSBSBSBS 2.9 kW

BNSBNSBNSBNS 121 126

BBHBBHBBHBBH 859 959


3620 October 2009

Steel box to host the upper silica

clamp on the marionetta

Steel box to host the upper silica

clamp on the marionetta

Silica Clamps

on the marionette

Silica Clamps

on the marionette

Silica anchorsSilica anchors

Coupling to the mirror flats through lateral supportsCoupling to the mirror flats through lateral supports

Silicate bondingSilicate bonding

The monolithic assembly on the mirrors


Crab Pulsar

The LIGO data gives no GW signal for

the Crab pulsar => set a superior limit

to the GW energy to no more than 4%

With a few months of data taken by Virgo

(best sensit @ 30 Hz), more results to

come soon for the Crab pulsar

Young neutron star, rotates 30 times/sec

The rotation period is slowing down (38

ns/day) due to some energy carried away

Other limits coming from LSC/Virgo joint data on LSC.org web site


Summary

The ground-based experiments have achieved their expected performance with the 1st generation

Not yet detected any GW but first data analysis set limits to some known sources, better results to come

They are ready to proceed to the 2nd generation detectors to detect GWs


Philippe Tourrenc’s action in the 80’s has now largely reached its goal and the detectors performances are beyond our hopes

Ground-based GW detectors: status of experiments and ...€¦ · •2007: CLIO (cryo detector),...

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