1. 1 PAY Review Meeting 1 18/3/2009 Piero Rapagnani 18/03/2009

2. 2 N and W Arms Monolithic Mirror Suspension Payloads - 1 Marionette for monolithic suspension (NI, WI, NE, WE) Same design as in Virgo+ MS payloads. If we keep the same distance between the suspension wires (5 cm), we could use the same pieces. Even if an auxiliary mirror should be put in the NI and WI towers, it would be important to keep the same marionetta design. Reference Mass for monolithic suspension (NE, WE) Same basic design as in Virgo+ MS payloads. Some expensive parts of the Virgo+ MS could be used. Reference Mass for monolithic suspension with compensation plate and heating ring (NE, WE) Same basic design as in Virgo+ MS payloads, with some modifications to include the CP and Heating Ring from TCS. Design will start next week. Recoil Mass for monolithic suspension Marionette (NI, WI, NE, WE) Same basic design of the Prototype Cryogenic Payload. Silica Parts (NI, NE, WI, WE) Silica fibers production and characterization Silica clamps Fiber/clamp welding and bonding PAY

3. 3 N and W Arms Monolithic Mirror Suspension Payloads - 2 Thermal Noise Optimization: being studied now by PPP (Piergiovanni, Punturo, Puppo) group. Local Control and Actuation: Same reference solution as used in Virgo and Virgo+. Changes eventually to be asked by the ISC group Open issues: Input from MIR: Choice of mirror dimensions to eventually machine fiber clamps directly on it. Possibility to have markers directly on the coating Input from OSD: Auxiliary mirror in the Input Towers? Complete redesign of NI and WI Payloads Experience gained with Virgo+ MS partially lost Heavy intervention on upper suspension More complex safety issues for monolithic suspensions PAY

4. 4 Central Area Payloads: do we need to suspend here also other auxiliary mirrors? BS Payload: RM for BS, Marionette for BS, MRM for BSRM for PR, PR Payload: Marionette for PR, MRM for PR SR Payload: do we need monolithic suspensions? Marionette for SR, MRM for SR RM for SR Steel wires for BS, PR and SR suspensions PAY Design of these payloads cannot start until the Optical Scheme is defined

5. 5 Benches Payloads: Marionette for IB (with suspensions for PRM1 and PRM3?) Marionette for DB (with suspensions for SRM1 and SRM3?) IMC Payload Recoil Mass Marionette PAY Design of these payloads cannot start until the Optical Scheme is defined : this impacts also on cost and manpower evaluation. Preliminary documents posted in the PAY area: - PAY AdV Design - PAY Construction Tasks - PAY Construction Tasks Form - PAY WBS

6. 6 PRM1 OSD2 OSD4 By Ettore

7. 7 PRM1 OSD2 OSD4 with no gaussian divergence :is this beam tracing OK ! ACTUAL SITUATION ?

8. 8 PRESENT SITUATION - 1 Virgo payload design criteria: - geometrical constraints given by SA, IVC, Pots - measurement of payload modes (not checked by modelling the overall suspension system) - measurement of bulk lowest frequency modes (RM,marionette…) - DC tilt adjustment (motors) - actuators (available space, force, coil aspect ratio, heating) - Eddy currents - Local controls (to allow Locking and AA activation) Virgo payload improvement during Virgo experience (from CITF so far): - mechanics: no multi-piece-bodies along the main beam (f i > 1 kHz) - Eddy Currents, magnetization. - Local controls (more efficient from marionette, but attention to coupling with roll !) - transversal pendulum noise improved by unplugging it !!! (actuation efficiency of actual solution depends on the coupling). - Reaction mass: using 0.6 Hz for locking is easy, successful driving noise reduction through reallocation attained, but with some work. By Ettore

9. 9 PRESENT SITUATION - 2 GENERAL LESSON: - marionette materials - simplest and compact shapes - no multi-pieces mechanics - BS payload site critical for diffused light - BS reallocation, but only to a limited extent (reasonably avoidable in the future) - PR reallocation not needed. - LC basically OK, with some patch needed (e.g. x sensing, roll coupling) - very important modeling the overall mechanical system - Local controls must be over-performing until automatic control signals (lock and angular) aren’t fully understood. MONOLITHIC PAYLOAD ESPERIMENTAL STUDY Design of monolithic suspension done on this base

10. 10 NDRC CASE: DESIGN DRIVING ISSUES - 1 1 > compatibility with Monolithic payload - OSD4: secondary mirror suspended by INPUT mirrors (now no reallocation to IM marionette); critical versus control alignment; critical versus FP NDRC alignment control noise coupling. ============================================================== Will NI/WI payload be TN limited with this system ? 2 > If no re-allocation on BS/PR simpler both OSD2/OSD4. 3 > Diffused light: constraints about clearance among beams around mirrors should come from optical tracing, their fulfillment will be checked according to mechanical possible drawings for OSD2/OSD4. 5 > both OSD2/OSD4 require - different marionettes with 3 tilts controlled. - DC counterbalance along transversal (x) - z control through Rmasses for PRM3,BS 4 > Electromagnetic crosstalk: minimal (or reasonable) distance among actuators 5bis > differential rad. pressure at the BS (OSD2) requires torque compensation (apparently also elsewhere even if to a minor extent) => F7 DC might be applied with respect to the ground otherwise an then an intermediate controlled mass might be necessary => further complication …

11. 11 NDRC CASE: DESIGN DRIVING ISSUES - 2 6 > LC design uneasy given the number of optical ports: perhaps OSD4 a bit easier 7 > Criticality of beam centering/control noise for telescope mirrors PRM1,PRM2,SRM2 BASIC QUESTIONS: > Should NDRC telescope mirrors also controlled via autoalignment (which ports?)? At present ONLY IMx are under LC+driftControl: in principle the light reflected from ITF can be referred in principle to IMx with possible further improvements of stability. What will happen with NDRC? > Can we draw modifications of tower basement vacuum chambers ? NOTE: PAY is considering also the vertical positioning of further mirrors needed for NDRC.