1. Status of VLPC Cryo-Cooler Cryostat Design Russ Rucinski (Alan Bross) Fermilab

2. Fabrication Drawings:  Drawings complete but not checked (as of 7/29)  Two main assembly drawings (on next slides) u Main assembly of lid assembly to vacuum container u Lid assembly, everything that attaches to lid  Detail drawings

3. Main Assembly Drawing

4. Lid Assembly Drawing

6. Detail drawings (& general information about them) Invar envelope assembly – Same as previously presented, 0.015” thick invar, top flange, bottom cap. G-10 stiffener panels – 25 mm thick, dimples spaced on 12.5 mm pitch. Traps envelope on all four sides. Held together with links at ends, and bolts with belleville springs. Upper thermal link – 10 mm copper, short flex section Lower thermal link – 10 mm copper, short flex section Stiffener clamps – 12 mm thick x 20 mm in clamping direction, stainless steel. Attached with bolts & belleville springs. Lid – 24 mm thick, cable heater groove, KF40 ports Vacuum Can – 24” pipe, nothing special

7. Engineering Details  Concept didn’t change since June KEK meeting. Finished up the details of the design since then.  Stiffener panels had to be very stiff. Thick G- 10 with dimples fit the bill for strength and low thermal conductivity. I have a minor concern about outgassing in vacuum space. May require active pumping.  Copper thermal links needed a stainless strong back (clamp) to apply 60 psi clamping pressure at cassette intercepts. Very little deflection (0.002”).  Heat loads/performance did not change after design was finalized.

8. Engineering Details  Thermal links contain a flexible section of copper mesh, 10 mm thick soldered into pocket in the copper. Lower has 2 flex sections since it attaches to the intercept itself and the bottom of the envelope.  Radiation heat load with MLI was 0.4 watts to upper stage, 0.6 watts to lower stage. A hard shield can be installed where easily feasible. Upper thermal clamp has tapped holes that can be used.  A second gas helium port was added to give some flexibility in solving potential pressure/temperature fluctuation problems of the cassette space. The cassette space is a very small volume. One might envision a bellows bag or a continuous flow through solution.

9. Thermal Calculations – Same as June, Only the picture changed. 50 Watts @ 60 K (Total for the cryostat) 65 K Clamp bar, 77 K in Cassette 7.5 K at Clamp bar, 8.0 K in Cassette 2.8 Watts @ 6.5 K (Total for the cryostat) Lid Heater (not shown) Temperature Control heater (not shown) Thermal links G-10 panels, low conductivity

10. Thermal Calculations – (same as June) Stage 1 (~ 60 K)Stage 2 (~ 7 K) Cassette7.7 watts0.82 watts Envelope15.0 watts0.45 watts Miscellaneous2 watts0.10 watts Total per slot25 watts1.4 watts Total for cryocooler50 watts2.8 watts Operating Point 65 % capacity at 1 st stage 55% capacity at 2 nd stage

11. Schedule  Hopefully by the time you are reading this, the detail drawings will be checked.  Design drafter is very good. Should have complete drawing package by August 6.  This is a delay of 2 weeks since June.