1. Cryovessel Engineering David Haase, Jan Boissevain, Ernie Ihloff WBS 1.3 - long lead time items Cryovessel Dilution Refrigerator Helium Liquefier

2. Logic Model Heat leaks and geometry of experiment  Cooling power needed for components  Cryogen usage  Selection of liquefier, dilution refrigerator  Construction of heat shields/cryovessel  Iterate

3. Major components of cryovessel

4. Heat Leaks to Experiment (5/06)

5. Estimated heating to 4.2K

6. Similar large dilution refrigerators

7. Dilution Refrigerators

8. NAUTILUS

9. Gravity wave detector cryovessels

10. Janis Research DR study 1. Specification of the cooling power, flow rate, geometry and liquid helium boiloff rates for the dilution refrigerator(s). 2. Design to show how the dilution refrigerator(s) would fit inside the cryovessel liquid helium entrainment volume. 3. Design of heat exchangers for optimal cooling of liquid helium in experimental volume. 4. Specification of physical size and siting requirements, electrical and cooling connections and ancillary equipment or supplies needed for operation. 5. Specification of safety devices and protocols required for safe operation of the system. 6.Estimate of cost and time needed for procurement and construction of the device.

11. Janis Research DR Study 1. Calculations and experience show that a dilution refrigerator can be constructed that would meet the refrigeration requirements of the nEDM experiment (80 mW at T= 0.5 K) 2. Janis estimated LHe boiloff rates of 5 – 6 l/hr 3. Janis does not produce such a dilution refrigerator but demonstrated a design and would be willing to custom-build it for the project. 4. The cost estimate for the dilution refrigerator system was significantly greater than the amount budgeted.

12. DR Procurement Options

13. Next steps  Meeting on Thursday with consultant  RFQ for dilution refrigerator construction  Continued iterations in cryovessel design