Attempting to Cost Estimate the nEDM Upper Cryostat Larry Bartoszek, PE Bartoszek Engineering 12/2/04

What’s the Goal? How accurate does the cost estimate need to be? Factor of 2? Factor of 5??? (Too much, right?) I don’t have good numbers because there are still too many unknowns. (I don’t even have bad numbers yet!) Large changes are being discussed up to this minute.

Ranges of Uncertainty The DOE uses the following contingencies for different types of estimates: Quote in hand for off-the-shelf item: 10% Engineering estimate: 15-25% Engineering estimates are also broken down by technical and schedule risks To call it an “engineering” estimate assumes that the item has been engineered High technical risk items can have contingencies of 50% or higher Is there anything in this apparatus that isn’t technically risky?

Status of current design nEDM is still very conceptual I think it would be a miracle if the latest numbers achieve a cost estimate accurate to 50%. Large uncertainties are in manufacturing processes associated with non-standard components For one small example, UCN-friendly superfluid-tight He valves operating at.3K, non-superconducting and actuated by LHe cylinders

Hidden costs: The large fiberglass structures will require custom tooling that must be included in the cost These will be very labor intensive and may not be fabricate-able by technicians at universities Some may need vacuum fixturing Temporary fixturing for assembly I would budget for a large FEA effort to verify the heat leak budget—similar to efforts we did for G0

Status Cont’d Jan’s model is exactly what we need to decide major features and carve out volumes We must not be fooled by the apparent level of detail of the model It is still a conceptual design, not a preliminary design “Thousands” of parts are still to be designed in (lots of fasteners) Many open issues on assembly, tool clearances, temporary supports, plumbing connections, etc…

What is the Upper Cryostat? Jan and I talked about whether the magnetic shielding of the main cryostat needed to extend all the way around the upper cryostat I got the impression from Doug that it did Jan is hoping it does not The interface vessel right under the Upper Cryostat is a no-man’s land that could reasonably be considered part of the Upper Cryostat Is spin preserved in an unshielded volume?

Upper Cryostat? This picture “stolen” from Jan Boissevain

Valve details The valves could be a major source of heat leak because they look like heat exchangers The actuator may be a custom LHe I piston and cylinder operating at 4K The valve flow path must be at ~.3K Is the plumbing acrylic? Stainless? Does stainless have a Tc? If plastic, is it epoxied for seals?

I know this is a conceptual image but: 1)A hydroform bellows will never last in fatigue 2)The dead volume is the heat exchanger This space fills with.3K He

Some other observations The following pictures and text were borrowed from Jan’s presentation My questions are added

4°K Shield Lead Super Conducting Shield Ferro-magnetic Shield Ferro-magnetic Shield Form Cosθ Coil Form How are these shells fabricated? What is the ferro-magnetic shield made of? (If iron, isn’t it too brittle at <4K?) How are CTE’s matched? How do you make corners like this? This picture “stolen” from Jan Boissevain

Ceramic Ball Contact mechanics calculates the size of the circular areas the ball makes in contact with the groove. The weight will cause the ball to impress dents in the flats that will increase thermal conductivity. Definitely an area to FEA for heat leak.

Conclusion I can’t cost estimate what I can’t see Is there any way we can focus more on the design so that we can get a reasonable cost when we have a more complete design?