1. G040065-01-R LIGO Laboratory1 Advanced LIGO Research and Development Update Dennis Coyne LSC Meeting at LLO 16 March 2004

2. G040065-01-R LIGO Laboratory2 Recent Progress Lots of research reported at the August, Hannover LSC meeting and some at the November, Hanford LSC meeting Wish only to give highlights on what’s happened in the interim

3. G040065-01-R LIGO Laboratory3 Pre-stabilized Laser LZH/MPQ studying the two head configuration »optimizing birefringence compensation Four Head Ring Laser »Tested new fiber- bundle design »Demonstrated >165 W

4. G040065-01-R LIGO Laboratory4 Input Optics High Power Test Lab at LLO »100W, good mode quality, single polarization, 1.06 um laser is non-trivial. ELS failed »IPG Photonics is de-rating one of their high power commercial systems. Delivery in ~3 months Low absorption, large aperture Faraday Isolator »Preparing a FI assembly with low loss TGG crystal for LHO (not thermally compensated) Electro-Optic Modulators (EOM) »New Focus to build EOMs on an OEM scale based on RTP-crystals »Expect to get one in a few weeks & tests Laser adaptive optics for mode matching »Preliminary measurements of lens power and modal contamination

5. G040065-01-R LIGO Laboratory5 Core Optics Components Held COC design requirements review Substrates »Absorption measured on two more, ~full size sapphire pieces confirm the first large sapphire measurements of ~60 ppm/cm average (~30 to 130 range) »Setting up further diagnostics and development of sapphire: –Annealing tests on large pieces at Crystal Systems has been delayed by funding –Annealing tests on small pieces at Stanford are proceeding –Parts for direct measurement of thermoelastic noise in Japan –Test piece to measure Q at low frequencies (~4 kHz) – results expected March –Caltech absorption measurements on intermediate size pieces match LMA-Lyon pattern (relative); calibration still uncertain –Annealing oven at Hobart and William Smith in operation – results expected soon »Downselect: June 2004 LIGO Lab (Caltech) VIRGO (LMA-Lyon)

6. G040065-01-R LIGO Laboratory6 Core Optics Components Coatings »Low loss coatings program with LMA-Lyon and CSIRO –1 st Q results for CSIRO tantala/silica  REO/Lyon/MLD (despite questions/problems with absorption and uniformity) –Hafnia/silica sample from Lyon are expected in ~ a week Absorption is ~ 5-6 ppm; will never reach the 0.5 ppm req’d Scatter is also higher, 20-40 ppm »High coating scatter loss –LHO ITM HR coating scatter loss >> entire loss budget for the nominal AdL design –Scatter loss from LLO ITM measurements planned –Plan lab surface measurement via focused surface scan/scatter detection use of the RTS instrument (Caltech) TNI »Working on reducing and understanding the noise floor repeatability and the effect of coating loss »Fused Silica (FS) –Reinstalled FS optics and obtained the same sensitivity! »Sapphire –Very recently installed sapphire test masses and locked the interferometer High Resolution Image of Scatter from the ITMx,2k HR Coating

7. G040065-01-R LIGO Laboratory7 Active Thermal Compensation (ATC) ATC »AdL “working” baseline has the compensation plate in the ITM reaction chain; Final review/decision in April »‘Staring configuration’ implemented at LHO; could also have AdL application in this form Gin Gin Experiment »Emphasis for Gin Gin experimental plan is radiation pressure effects and instabilities »Completed calculations of thermal lensing and residual power in higher order modes »Compensation plate (Ø160 mm fused silica Heraeus 311SV) being polished & coated »Initial (in air) Mach Zehnder interferometer measurements for small compensation plate are encouraging and confirm simulations

8. G040065-01-R LIGO Laboratory8 Seismic Isolation: In-chamber, Active, Two-Stage System ETF testing continues (sensor characterization, electronics noise reduction, transfer function measurements, damping & isolation controls, …) In-vacuum actuator development RFQ HAM & BSC Prototype mechanical design »Have held a few in-process design reviews »Difficult to meet stiffness requirements and extremes in payload mass properties »Design review late March

9. G040065-01-R LIGO Laboratory9 Suspensions Triple, mode cleaner “controls” prototype to be tested at LASTI this summer Quadruple “controls prototype” development emphasis by US & UK team members OSEM design concept proposal/review/decision in April »SUS/UK team investigated interferometric & geometric sensors »Preliminary recommendation: use of the interferometric sensor where high sensitivity is required, shadow sensors elsewhere Eddy current damping demonstrated as viable alternative/supplement to active damping BS & FM to have same triple suspension ‘chains’ Set BSC chamber pendulum lengths Univ. of Glasgow is developing a ~100W CO2 laser pulling/welding machine for silica ribbons/fibers »EGO funded »Optical thickness profiling device to be developed Ear design / ear bond thermal noise »Finite element analysis of bond loss »Alternate geometries studied QUAD SUSPENSION TRIPLE SUSPENSION

10. G040065-01-R LIGO Laboratory10 Systems »Layouts –Improvements in the vertical wedged optics layout & calculation of all vertical coupling –Progress on horizontal wedged optics layout –Payload mass properties estimates for each chamber (for SEI design) »Requirements –Records Of Decisions/Agreements (RODA) –AdL Vacuum Outgassing requirements & Subsystem budget –Subsystems required to have email forums & web pages System Tests »LASTI –Completing HEPI –Revised plan for AdL testing –MC Triple suspension this summer »40m –SR soon! Power & Signal Recycling Cavity Layout (non-folded interferometer)

11. G040065-01-R LIGO Laboratory11 Systems -- Interferometer Sensing & Controls (ISC): 40m Lab Fabry-Perot Michelson Configuration »Robust locking (Michelson, common- mode arm and differential mode arm cavities) »Improved sensitivity Dual Recycled Configuration »All installation has been completed! »The mode cleaner and Fabry-Perot Michelson have locked! »Efforts to lock the dual-recycled Michelson are underway! Thermal noise

12. G040065-01-R LIGO Laboratory12 Advanced LIGO R&D Significant progress! LIGO Management »getting detailed cost and schedule model updated »using to make revised R&D plan from the ground up that fits constraints, has needed flexibility NSF studying the Advanced LIGO Proposal …meanwhile, lots of good science and engineering going on!