1. 1 1.Status a.Design requirements: almost complete. b.Preliminary design: on-going 2.WBS a.Tasks and subtasks b.Manpower, responsibility issues 3.Interfaces with other subsystems ISC workshop: Status, WBS, Interfaces

2. 2 I. Status – Design requirements (1/2) Alignment * AC alignment of recycling cavities - extra modulation frequencies (M.M. 19/06/08) * non-Anderson technique for arm cavities – Pick-offs in reflection of arms (M.M. 19/06/08) * simulation software TBD * radiation pressure: mitigation of unstable Sidles-Sigg modes – LIGO-P030055-B Steady state locking * Interferometer with signal recycling cavity - G.V. VIR-030B-08 and VIR-032A-08 * Auxiliary DoF’s noise and feed-forward - VIR-050A-08 * DoF’s diagonalization: multi-modulation scheme - G.V. VIR-049A-08 * DC offset: Radiation pressure and instabilities: mitigation - Nature 444 71 (2006) * Simulation software: optickle * Shot noise correlations – note from A. Heidmann for a power stabilization loop Topic – description or conceptual design solution

3. 3 I. Status – Design requirements (2/2) Lock acquisition * Radiation pressure on arm cavities – lock at low power * Arm cavity finesse: ringings, linearization, servo BW – under study with CALVA * DC detection and instability wall – compensation with digital spring? Test at CALVA? * Simulation software TBD Parametric instabilities * Simulation software (frequencies, R factors) * Behavior? * Mitigation?

4. 4 I. Status – Preliminary design Alignment * Radiation pressure on single arm cavities M.M. VIR-109A-08 * sensing configuration * driving configuration * … … see Maddalena’s talk Steady state locking * Simulation, DoF couplings G.V. VIR-068B-08, VIR-069B-08 Specifications on mirror motion G.V. VIR-083A-08 * Modulation frequencies and environmental noises F.P. 12/02/2009 Lock acquisition * reference solution: auxiliary laser (CALVA-like)

5. 5 II. WBS - Tasks and subtasks: see Excel document - Manpower, responsibilities: difficulties, interactions with Virgo+ discussion at activity level (alignment, steady state locking, P.I., lock acq.) - Planning Design requirementsDRD Conceptual designCDD Design specificationsDSD pre-commissioningsimulations, lab experiments

6. 6 III. Interfaces with other subsystems Planning, priorities: - a global planning for design activities is missing Requests from subsystems (explicit, anticipated): integrated in WBS “design specifications” - DET: photodiodes, DC powers, signal excursions,… - INJ, LAS: frequency, power stabilities, specs on IMC - OSD: constraints on finesse/arm cavity lock acquisition? - PAY: correction signal excursion Requests to subsystems - OSD: interferometer asymmetries (losses, finesse), expected contrast defect => Freq. stab. specs., DC detuning, etc. recycling lengths => modulation frequencies - PAY/SUS: expected mirror motion (longitudinal, angular) => specs on servo loops, on LCs, … - DAQ/DET: quadrant photodiode response => modulation frequencies Inter-system studies payload definition (PAY, ISC, OSD, TCS) To be agreed with other subsystems: - common modeling software? See complete list in WBS

7. 7 Next steps Talks for today Alignment: M. Mantovani Steady State Locking: F. Bondu Lock Acquisition: F. Cavalier Parametric instability: P.-F. Cohadon Additional manpower, first priority A formal internal review, with IRC, to be planned?