1. LAr1-ND Conceptual Design Review of Status June 25 Craig Thorn

3. Introduction -These slides summarize all the work that has been performed so far on the conceptual design of the LAr1-ND cryostat and cryogenic system. -They present solutions to some of the initial issues that had been identified. -They list the preliminary requirements of the membrane cryostat and of the cryogenic system. -They list the current list of outstanding issues with proposed ways to address them. 3

7. Design Drivers Maximize active LAr volume in a limited enclosure (SciBooNE Hall) Maximize electron mean free path (minimize impurities) Maintain low LAr flow, especially turbulent flow (keep space charge simple) Eliminate LAr boiling (reduce breakdown probability)

8. Cryostat System 8

10. Cryostat Configuration in the Initial Proposal

11. Top View 4,900 mm 4,400 mm 5,100 mm 7,000 mm Insulation 250 mm Insulation 450 mm Insulation 250 mm Desired Side Penetration for LAr pump.

12. The HV feedthrough does not have to be in the center of the CPA in this view 4,800 mm Insulation 250 mm Insulation 450 mm 4,400 mm Insulation 250 mm Side View

13. Back View Insulation 450 mm Insulation 250 mm 4,800 mm 1,200 mm Desired Side Penetration for LAr pump. 1,000 mm

14. A Conceptual Model of the Cryostat+TPC

15. Heat Exchange Panels in LAr Cooled with 3.6 atm LN2

16. ParameterValue Type of structureMembrane cryostat inside an existing concrete pit Outside reinforcementExisting concrete pit Cryostat Volume129 m^3 FluidLiquid Argon (LAr) Liquid Argon total mass180 ton Inner dimensions (flat plate to flat plate)4.4 m (W) x 6.1 m (L) x 4.8 m (H) Depth of liquid argon4.8m (All the gas in the “neck” region on the side) Insulation (different thicknesses to match the size of the existing pit) 0.25 m (bottom), 0.45 m (top) 0.45 m (beam left/right), 0.25 m (beam upstream/downstream) Primary membraneSS 304/304L Operating gas pressure1.0 psig (~70 mbar) VacuumNo vacuum Design Pressure3.0 psig (~207 mbar) Design Temperature77 K (liquid Nitrogen temperature for convenience) PenetrationsOne through the insulation and all the others through the neck region. Duration10 years Thermal cycles10 complete cycles (cool down and total warm up) Cryostat Current Design Parameters

17. Questions Cost: Requested clarification. Varies from $600k to $3M (both +/-30%). ✓ Schedule for design, procurement of materials, construction. Requested clarification. Varies from 14 mo to 25 mo (both +/-30%). ✓ LAr Pump Location: ✓ – Baseline is pump inside the cryostat. Is it possible to have this side penetration from the bottom of the cryostat to withdraw liquid and locate the pump outside the cryostat? – It is technically possible, but forbidden by the law for LNG tanks. Need to check if Fermilab allows it for LAr. GTT is easier because of the geometry of the membrane panels. IHI needs to explore to locate it in the corner, otherwise it is at 1.5m of elevation from the floor. – If pump is moved outside, the cryostat length will be reduced from 6.1 m to 5.1 m to accommodate the pump at the end of the hall. Is it possible to fill the tank completely and have gas only in the neck region? YES ✓ Dimensions: GTT can make the exact dimensions. Slight changes for IHI (See next slide). ✓ Insulation: are the different thicknesses an issue? We want to match the size of the existing concrete pit. No problem. ✓

18. Schedule Procurement (11 mo) Engineering (9 mo) Construction (10 mo) 9 mo 14 mo 24 mo IHI Procurement (6 mo) Engineering (5 mo) Construction (3 mo) 5 mo 11 mo 14 mo GTT Not to scale

19. IHI Dimensions

20. TPC High Voltage Feedthrough: TPC HV FT is a warm FT right on top of the Cathode plane with its own nozzle. Ullage region of the HV needs to be connected to the ullage region in the “chimney” to maintain stable liquid level in the HV nozzle

21. TPC Signal Feedthrough Baseline : Warm FT. “MicroBooNE” Style. Options: Long “Cold” FT dipping into the liquid. Eliminates the exposed cables in the gas region. ATLAS style or a new design??

22. Cryogenic System 22

23. Purification/Filtration systems How many are needed? Gas recirculation: GAr purification during initial cleaning. Filling: LAr purification. Ops: GAr boil off purification and no LAr purification (idea). Liquid phase: condense and then purify before sending back to the tank? Gas phase: purify and then condense before sending back to the tank? Is it feasible to purify the LAr at the beginning during the filling and no more, just the boil off GAr? What is the outgassing rate from the “warm”/gas region? Does it match the boil off rate or do we have to pull GAr to overcome the outgassing? If so, how? Pump? Will the bulk of the liquid be pure enough if it is not continuously purified? Or will it need to be purified as well? What kind of LAr/GAr purification system? Mol sieve + Copper beds Are there more types of mol sieves? 23

24. Cryogenic System – 1 If possible, the goal is to not purify the bulk of the liquid during regular operations, but only the boil off gas. The idea is to fill the membrane cryostat completely and reach the expansion tank with the liquid to minimize the outgassing to that region only. (No outgassing in the liquid). To purify the LAr during the initial filling via molecular sieve and copper beds to remove respectively water and oxygen. To purify and recondense (or vice versa) the boil off gas from the expansion tank using molecular sieve and copper beds: It may be necessary to suck the boil off gas in order to overcome the outgassing flow rate in the expansion tank. It may be possible to use the same purification system used during the LAr filling. To purify the bulk of the LAr, if needed. LAr pumps outside the cryostat to force LAr recirculation. To handle the LAr/GAr and LN2/GN2 flows: Initial cleaning  GAr purging and venting, GAr recirculation and purification. Ops  cool down, LAr filling, GAr boil off purification and re-condensation, LAr return to the tank. 24

25. Cryogenic System – 2 To recondense the boil off gas: LAr condenser and LN2 phase separator. Pressure control: PSV, VSV, Auto/Manual venting. To handle the LN2/GN2 to/from the heat exchanger panels inside the membrane cryostat. To handle the GAr purge inside the insulation. Instrumentation and diagnostics: T and P sensors, flow meters, etc., Analytical instruments to measure the contamination, in-line Purity Monitors?, etc. To develop the control system. 25

26. Requirements Purity: 10 ms electron lifetime (< 30 ppt O2 equivalent contamination). Piston purge rate of rise: 1.2 m/hr. Membrane cool-down flow rate: value to come from simulations of cool- down per vendor’s specifications (< 10-15 K/hr). GAr Purification flow rate: value to come from simulations of outgassing from the top region. LAr Purification flow rate (filling/operations if needed): 1 volume change/day (4.5 m^3/hr = 20 gpm). Cooling power: value to come from boil off gas and outgassing flow rate. Pressurized LN2/GN2 heat exchanger in tank: size to come from simulations of convective currents (< 1 mm/s) and max cool down load. High reliability of the LN2 cooling system: value to come from simulations of boil off and cooling power. If possible, portable system(s) with quick connections to/from the cryostat. 26

27. Outstanding issues – 1 Simulations of outgassing versus GAr purification needs  to determine if LAr purification is needed and GAr purification flow rate. Simulations of convective currents inside the bulk of the LAr  will determine the amount of cooling power. Studies on how to minimize noise in the vicinity of the wires. Studies on how the top plate will be supported (most likely done by the membrane cryostat vendor). LAr Pump: – Currently Inside. Outside better, but will reduce the length by 1.0 m. – Need to see how to isolate the pump electrically and mechanically from the TPC. Issues with electronic noise and microphonics. – This is related to the overall grounding plan. Need to update MicroBooNE’s grounding plan. – Two pumps in current design (Inside), only one if outside. 27

28. Outstanding issues – 2 Installation: – How will the TPCs be installed? – Do the cryostat dimensions need to be revised to account for the installation of the TPCs? – Does the location of the openings (feedthroughs and installation hatch) need to be modified? – How do we connect the cables to the Feedthroughs? – How do we test the APAs during installation?

30. Summary 30 LAr1-ND proposes to use the membrane cryostat technology for a new on- axis Near Detector using the R&D and experience from the design and construction of similar LAr-TPC detectors. It presents several innovative aspects: – The absence of the ullage and the use of a GAr region on a side to compensate for the liquid/vapor transition. – The use of cold feedthroughs. – The idea of purifying only the boil off GAr from the top region during operations and not the bulk of the liquid. – The use of LN2 cooled heat exchange panels inside to minimize the LAr boil-off. A conceptual design has been developed. Preliminary requirements for the cryostat have been outlined and cost/schedule information from vendors acquired. Preliminary requirements for the cryogenic systems have been outlined and will need simulations and additional studies to be completed. It is now possible to start engineering the features of the cryostat and the cryogenic systems.