Overview of the Advanced LIGO Upgrade

Giles Hammond, SUPA, University of Glasgow

on behalf of the LIGO Scientific Collaboration and the Virgo Collaboration

APP 2009, University of Edinburgh, 7th-9th June 2009

Overview of the presentation

Status of the worldwide interferometer network

Noise sources in interferometers

GEO 600

Advanced LIGO astrophysical reach

Advanced LIGO topology

Technology development underway for Advanced LIGO

Summary

Worldwide Network of Interferometers

GEO600TAMA, CLIO

LIGO Livingston

LIGO Hanford

4 km2 km

600 m300 m100 m

P. Shawhan, LIGO-G0900080-v1

4 km

VIRGO 3 kmLIGO Livingston

Noise Sources in Interferometers

LASER

test mass (mirror)

photodiode

Beamsplitter

Wavelength & amplitude fluctuations

Residual gas scattering

Seismic Noise

seismic noise

Thermal (Brownian)

Noise

mirror thermal noise

Quantum Noise

“shot" noise

radiation pressure

shot noise

sensitivity better than ~1 attometre on 10ms timescales

GEO 600

UK-German collaboration

University of Glasgow Hough, Rowan, Strain, Ward, Woan, Hammond, Hild (from Oct 09),

Heng, Robertson and colleaguesCardiff University Sathyaprakash, Schutz, Grishchuk, Sutton, Fairhurst and

colleaguesUniversity of Birmingham Cruise, Vecchio, Freise and colleaguesAEI Hannover and Golm Danzmann, Schutz, Allen and colleaguesColleagues in University de les Illes Balears

Novel technologies make GEO unique and allow it to run in coincidence with the larger LIGO (and Virgo) instruments

Unique GEO Technology 1

Advanced interferometry

One of the fundamental limits to interferometer sensitivity is photon statistics

Signal recyclingmirror

Modecleaner

Power recyclingmirror

Laser

Power recycling effectively increases the laser power

Signal recycling – a Glasgow innovation, trades bandwidth for improved sensitivity

Unique GEO Technology 2

Monolithic Suspensions

reduces thermal noise

Ultra-low mechanical loss

suspension at the heart of

the interferometer

Advanced LIGO Astrophysical Reach

Enhanced LIGO (≈2009)

Advanced LIGO (>2014)

LIGO

Advanced LIGO Upgrade

Work is currently underway for a major upgrade to the LIGO detectors (Advanced LIGO) with a x10 increase in strain sensitivity (x1000 increase in volume)

2011-2012 Install, 2013-2014 Commissioning, >2014 S6 science run

In addition, VIRGO and GEO will also undergo upgrades to Advanced VIRGO and GEO-HF respectively

Advanced LIGO concept is based on the technologies evolved for GEO 600 (signal recycling and monolithic suspensions)

Parameter LIGO Advanced LIGO

Input Laser Power 10W 180W

Mirror Mass 10kg 40kg

Topology Power recycled Fabry-Perot arm cavity Michelson

Power/Signal recycled Fabry-Perot arm cavity Michelson

Low frequency performance

f> 50Hz f>10Hz

Mirror suspension Single metal pendulum Quadruple monolithic pendulum

Advanced LIGO Topology

Completely new interferometers at the same observatory sites

New optical layout with signal recycling

Signal recyclingmirror

Modecleaner

Power recyclingmirror

~180 W ≈830kW

Active thermal compensation

Mirror Coatings

Coating noise will limit sensitivity of Advanced LIGO around 40-200Hz

Work is ongoing to provide best estimates for coating properties in order to assess noise budget

Ta2O5 is the dominant source of dissipation in current SiO2/Ta2O5 coatings

Doping the Ta2O5 with TiO2can reduce the mechanical dissipation by ~40% for overall coating

The Coating subgroup is working closely with coating vendors (CSIRO, Australia and LMA, France) to formulate low noise coatings

Work carried out by Coating subgroup (in which University of Glasgow plays a key role)

Ta2O5 layer

SiO2 layer

Seismic Isolation and Suspensions

RAL, University of Birmingham and University of Glasgow play essential roles in this work

40kg silica test mass

parallel reaction chain for control

four stages

Hydraulic pre-isolatorIn-vacuum seismic isolation platform

Quadruple pendulum

Monolithic Lower Stage

University of Glasgow is providing the monolithic suspension for Advanced LIGO

40kg test mass suspended by 4 silica fibres

Fibres are butt welded onto silica ears bonded to the test mass

Decision to go for an upsizing of the proven GEO ears

Laser Pulled Fibres

Laser pulling machine (a Glasgow led development with machines now in the US and Italy)

Laser Welding

test ear

Gold coated mirrorZirconia tipped

tweezers

Translation stage to move stock down

back side accessible via mirror reflection

40kg Test Suspension

Demonstrated in Glasgow

Summary

Current LIGO detectors are operating at design sensitivity and have completed a successful S5 science run together with GEO 600 and VIRGO

Enhanced LIGO will begin operation during 2009 with an additional factor of 2 in strain sensitivity

The Advanced LIGO upgrade (2011-2014) will achieve a factor of 10 increase in strain sensitivity over current LIGO

There is significant technology development underway for the Advanced LIGO upgrade both in the US and Europe which is based on key technologies demonstrated in GEO 600

UK partners are working hard on providing R&D for Advanced LIGO which includes: optical sensors, monolithic suspensions, coating research and (RAL, Glasgow and Birmingham)

• The UK (and GEO) leadership role in Advanced LIGO is very strong and recognised by a seat for STFC on the Oversight Committee for the LIGO project.

Advanced LIGO is making excellent progress

LIGO Scientific Collaboration