1. nEDM Collaboration Meeting 5/2008 Preliminary Engineering Report nEDM Central Detector John C. Ramsey Los Alamos National Laboratory

2. nEDM Collaboration Meeting 5/2008 Objectives Toward CD-2! Highlight changes since the last collaboration meeting Sound out assumptions –Materials choices –Design rationale –Component placement –Interfaces with other subsystems Voice concerns –See list above! Obtain feedback

3. nEDM Collaboration Meeting 5/2008 Major assembly assumptions What is here is in no way set in stone! Material of choice wherever possible is acrylic (PMMA) to minimize thermal contraction mismatches We are able to coat the acrylic for the electrodes and return

4. nEDM Collaboration Meeting 5/2008 Central volume cap Now provides half of the acrylic assembly support (assembly also supported upstream) Possible feed through shown based on David’s concept

5. nEDM Collaboration Meeting 5/2008 HV return and support Provide structural support to all components Intermediate support plate also and back plate now provide light guide support Upstream support from central volume wall is now in place

6. nEDM Collaboration Meeting 5/2008 Electrode assemblies Skewed legs stiffen the assembly “Kink” in HV feed to clear light guide alignment components Electrode support plate also now acts as a light guide support

7. nEDM Collaboration Meeting 5/2008 High Voltage Electrode Capacitor For Larry… Capacitor electrode components have been redesigned to withstand 1000 lbs axial force

8. nEDM Collaboration Meeting 5/2008 Measurement cell assemblies Bonded acrylic plates Extended cell walls provide clearance for light-guide alignment components

9. nEDM Collaboration Meeting 5/2008 Light guides and PMTs We have eliminated the guides downstream of the central volume cap –Assuming that PMTs function without mumetal shields –Tito will be checking this assumption Light guides have been added to the model –Currently represent bonded strips throughout –Simple alignment guides and light guide to measurement cell interface –Not currently enough support!

10. nEDM Collaboration Meeting 5/2008 3 He service to the measurement cells 2” OD, 1.5” ID acrylic piping (per George’s assumptions) Slipping ball joints allow for system contraction Extensive use of PTFE (or other) bellows! Addition of bellows seals and “breathers” on V1 valves

11. nEDM Collaboration Meeting 5/2008 SQUIDs Brackets mounted above SQUIDs to clear V1 valve Individual silicon substrates resting on acrylic pads Slotted to control location while allowing for thermal contraction Filling SQUID?

12. nEDM Collaboration Meeting 5/2008 Insertion/extraction scenario To remove or install the central detector assembly, all services must be disconnected and stowed overhead PMT assemblies must be removed Insertion/extraction fixture may then be attached Note that this is occurring with magnet package and central volume supports in place (not shown)

13. nEDM Collaboration Meeting 5/2008 Room temperature sag analyses Initial models showed how helpful upstream support would be Design currently showing about.01 sag (discounting light guides)

14. nEDM Collaboration Meeting 5/2008 Room temperature modal analyses Early models performed for room temperature, no light guides Showed significant natural harmonics near 60 Hz Addition of light guides and cold temperature materials characteristics should provide a more realistic analysis

15. nEDM Collaboration Meeting 5/2008 How prepared are we? Per Martin’s slide at the February collaboration meeting: –Specifications and goals –A breakdown of the subsystem into subassemblies –Assembly drawings of all subassemblies (the model) –Finite element analyses where appropriate –Other simulations where appropriate to back up specs –Heat transfer and dissipation where appropriate –Justification of tolerances –Compatibility with neighboring parts –Compatibility with other subsystems Fully prepared: Under way: Needs a lot of attention:

16. nEDM Collaboration Meeting 5/2008 How prepared are we? Continued: –Accounting for CTE’s if dissimilar materials where needed –Meeting materials specs for n-activation, n- absorption, and 3 He-depolarization, magnetism, electrical conductivity, etc. –Safety issues –Value engineering (cost minimization) –Assembly scenarios –Required tests –Service and repair scenarios Fully prepared: Under way: Needs a lot of attention:

17. nEDM Collaboration Meeting 5/2008 Current and future efforts Address the red and yellow stuff! More FEM models (cold) Further sealing experimentation Heat load evaluation Wire routing More detailed insertion/extraction Continue iterations and development in coordination with the various relevant subsystems