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, 7 th -9 th 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 GEO600 TAMA, CLIO LIGO Livingston LIGO Hanford 4 km 2 km 600 m 300 m 100 m P. Shawhan, LIGO-G v1 4 km VIRGO 3 km LIGO Livingston

Noise Sources in Interferometers LASER test mass (mirror) photodiode Beam splitter 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 colleagues Cardiff University Sathyaprakash, Schutz, Grishchuk, Sutton, Fairhurst and colleagues University of Birmingham Cruise, Vecchio, Freise and colleagues AEI Hannover and Golm Danzmann, Schutz, Allen and colleagues Colleagues 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 recycling mirror Mode cleaner Power recycling mirror 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) Install, 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) ParameterLIGOAdvanced LIGO Input Laser Power10W180W Mirror Mass10kg40kg TopologyPower recycled Fabry-Perot arm cavity Michelson Power/Signal recycled Fabry-Perot arm cavity Michelson Low frequency performance f> 50Hzf>10Hz Mirror suspensionSingle metal pendulumQuadruple monolithic pendulum

Advanced LIGO Topology Completely new interferometers at the same observatory sites New optical layout with signal recycling Signal recycling mirror Mode cleaner Power recycling mirror ~180 W 830kW Active thermal compensation

Mirror Coatings Coating noise will limit sensitivity of Advanced LIGO around Hz Work is ongoing to provide best estimates for coating properties in order to assess noise budget Ta 2 O 5 is the dominant source of dissipation in current SiO 2 /Ta 2 O 5 coatings Doping the Ta 2 O 5 with TiO 2 can 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) Ta 2 O 5 layer SiO 2 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-isolator In-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 mirror Zirconia 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 ( ) 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