LAr1-ND Conceptual Design

Review of StatusJune 25

Craig Thorn

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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.

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)

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Cryostat System

Cryostat Configuration in the Initial Proposal

Top View4,

900

mm

4,40

0 m

m

5,100 mm

7,000 mm

Insulation 250 mm

Insulation 450 mm

Insulation 450 mmInsulation 250 mm

Desired Side Penetration for LAr pump.

The HV feedthrough does not have to be in the center of the CPA in this view

4,80

0 m

m

Insulation 250 mm

Insulation 450 mm

4,400 mm

Insulation 250 mm

Side View

Back View

Insulation 450 mm

Insulation 450 mm

Insulation 450 mm

Insulation 250 mm

4,80

0 m

m1,

200

mm

Des

ired

Side

Pen

etra

tion

for L

Ar p

ump.

1,000 mm

A Conceptual Model of the Cryostat+TPC

Heat Exchange Panels in LArCooled with 3.6 atm LN2

Parameter Value

Type of structure Membrane cryostat inside an existing concrete pit

Outside reinforcement Existing concrete pitCryostat Volume 129 m^3Fluid Liquid Argon (LAr)Liquid Argon total mass 180 tonInner dimensions (flat plate to flat plate) 4.4 m (W) x 6.1 m (L) x 4.8 m (H)Depth of liquid argon 4.8m (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 membrane SS 304/304LOperating gas pressure 1.0 psig (~70 mbar)Vacuum No vacuumDesign Pressure 3.0 psig (~207 mbar)Design Temperature 77 K (liquid Nitrogen temperature for convenience)Penetrations One through the insulation and all the others through

the neck region.Duration 10 yearsThermal cycles 10 complete cycles (cool down and total warm up)

Cryostat Current Design Parameters

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. ✓

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

IHI Dimensions

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

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??

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Cryogenic System

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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?

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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.

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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.

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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.

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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.

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?

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Summary• 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.