January 20, 2009 ET-WP3 Geometryy 1 ET Geometry/Topology Some possible studies January 20, 2009 B. Mours

January 20, 2009 ET-WP3 Geometryy 2 ET vs the Ultimate Advanced ITFs Remarks:  The detectors are in a network  ET will have more than one ITF  ET Geometry/Topology depends on the other existing detectors Questions:  What makes ET unique? »The low frequency »The full spectrum??  What could be the “ultimate” sensitivity of AdL/AdV/LCGT? »Could they do as well as ET at high frequency? – Ready to loss the low frequency part of the spectrum By the way, this is a key question when selling ET… S. Hild

January 20, 2009 ET-WP3 Geometryy 3 Pointing Typical timing resolution   t ~ 1/(f typical *SNR) For low frequency signals  Pointing probably not from timing »SNR 10; 10 Hz ->  t ~ 10ms = LLO-LHO distance »For usual L-V signal (100Hz-1kHz) pointing resolution is a few degrees → for a 10Hz signal ~ 1 radian…  Direction from signal amplitude probably as good as time resolution To be investigated S. Hild

January 20, 2009 ET-WP3 Geometryy 4 ET layout Basic question: For a given infrastructure cost what is the best set of ITFs?  Geometry? »Triangle, one site L shape, two sites L shape, other ?  Multiple frequency bands per site? »High Frequency + Low frequency ITFs, tunable ITF?  Orientation?  How to best use AdV+ & AdL+? »Location/orientation with respect to the existing site (LIGO/Virgo) »To which extend could we rely on AdV+ a& AdL+ for source location? »What if there is or there is not an LCGT/Australian detector?  What are the constrain/impact for an US ET?  Phasing of the construction/commissioning of the ITFs? ? or L shape or ?

January 20, 2009 ET-WP3 Geometryy 5 Input for the basic question? Basic question: For a given infrastructure cost what is the best set of ITF? What is the model the infrastructure cost?  Fix the overall beam tube length?  Include some cost overhead (extra vacuum chambers, access..) per ITF?  Need a more refine model? What are the criteria for “Best”  Select a few leading science case: »Binaries inspiral for cosmology, i.e. (which masses?) »Stochastic signal »High SNR event (which is the most interesting frequency band?)

January 20, 2009 ET-WP3 Geometryy 6 Rough Actions Plan Estimate the ultimate AdV/AdL/LCGT sensitivity  Single or two frequency bands ITF for them? Study the frequency dependence of the pointing capability  Timing vs amplitude Analytic study for several configurations  Compute (use/collect existing tools/results): »Beam pattern »Range »Limit for stochastic signals Do Monte Carlo studies  Focus on distance range and resolution on source location  Study with coherent analysis  Include simulation of dead time; operation schedule  Use the LV coherent analysis as a debugging & bench mark