1. 1 PAY & OSD Piero Rapagnani 26/02/2009

2. 2 Fatal interference with current geometry: deep redesign of the payload needed Positioning another payload close to the monolithic suspension could be critical both during assembly and operation Piero Rapagnani 26/02/2009 Optical Scheme 4

3. 3 Optical Scheme 3 Piero Rapagnani 26/02/2009

4. 4 Configuration possible displacing by 100 mm PRM2 and SRM2 towards PR and SR PRO: - Steel wire suspensions are less critical for assembly and operation -System to be deeply redesigned anyway CON: - Local Control Setup? - Probably the three payloads cannot be mounted all together: change the bottom flange diametre ? 1 m BS Payload - Optical Scheme 3 Next Step: Draft of a possible configuration, including RM and Marionetta for PRM2 and SRM2, in the following days Piero Rapagnani 26/02/2009

5. 5 Optical Scheme 3: further proposal to avoid PRM1 on the injection bench: Configuration possible, if there are no monolithic suspension on PRM3 and SRM3. - Local control, weight and geometry issues to be verified. Piero Rapagnani 26/02/2009

6. 6 Optical Scheme 3: further proposal to avoid PRM1 on the injection bench: Configuration possible, if there are no monolithic suspension on PRM3 and SRM3. - Local control, weight and geometry issues to be verified. Piero Rapagnani 26/02/2009

7. 7 Resuming, this configuration: PR and SR BS PRO’s: The monolithic payloads remain with almost the same design being developed for Virgo +. This will preserve the experience that we shall gain (hopefully) with Mon. Susp. in Virgo + Restricts any changes due to the optical configuration to three towers. Allows valves before the input mirrors? The BS and SR payload have to be redesigned and built anyway. Complex payloads with steel suspensions are “easier” to manage. The small additional payloads will be probably mounted after the main payload: this operation is critical with Mon.Susp. CON’s: The BS and PR suspensions probably must be retuned for a heavier load. Prototyping and modelling is essential …… Piero Rapagnani 26/02/2009

8. 8 Nothing is impossible for the man who doesn’t have to do it himself A.H.Weiler (New York Times Editor and Critic, 1909 - 2002) Piero Rapagnani 26/02/2009