1. Defining the volumes and functions of the cryogenic suspension Discussion guidance Kashiwa October 10 2012 JGW-G1201312

2. Aim of the meeting Following the discussion of last week in Hongo Try to define some of the required characteristics of the mirror suspensions Starting from the cryostat dimensions to start defining the geometry of the suspensions and of the vacuum chambers connecting the SAS in the well to the cryostat

3. We need to define: This vacuum structure containing the bottom filter The geometry and the functions of the components in here

4. We need to define: This vacuum structure containing the bottom filter The geometry and the functions of the components in here

5. The side view Warm Bottom filter similar to that of the type B Addition of three springs for a Cold Filter mass

6. Intermediate mass The intermediate mass will be controlled from a recoil mass like in type B It will need cryo springs for thermal noise reduction

7. Cryo springs The type of type of cryo springs will depend on technological developments Will one layer of silicon spring suffice?

8. Cryo springs What springs ? Silicon on mirror Metal looking up? Decision later

9. Sapphire mirror suspensions: Options on the table Nail headed rods Silicon springs and flexures Compatible with same attachments to mirror Which length needed?

10. Cryo baffle req.s Baffle is large Needs to be suspended Need to track mirror to avoid wrapping A stable platform is convenient to filter the heat links

11. Controlled platform A controlled platform suspended from the bottom filter vacuum chamber is the solution Control actuators from the cryostat bottom Soft spot of HC actuators sufficient to reduce coupling

12. Platform sensors Sensing of the mirror position on a support on the platform, Co-located with the lock acquisition actuators

13. Cryogenic considerations 11 wire penetrations through the roof of the cryostat Platform and baffle attached to heat shield Cold path to the mirror connected to: – Platform (mechanically, not thermally) – filter mass, – intermediate recoil mass – Recoil mass – Mirror

14. Top view: does it all fit ? Barely fits Not much free space

15. Other options on the table What other studies have been done? What other options do we have? What parts or functions have been forgotten?