SBND Cryostat Requirements
David Montanari, Michael Geynisman, Dimitar Mladenov, Joe
Howell
14 October 2015
Introduction
• Same cryostat requirements as presented for the past
months.
• Same layout of penetrations at the top as presented by Joe
H. in Aug 2015.
• Discussions between CERN and Fermilab on layout of top
plate ongoing.
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David M, Michael G, Dimitar M, Joe H | SBND Cryostat Design
Oct 14, 2015
Cryostat requirements – 1
Parameter
Value
Type of structure
Membrane cryostat (5% ullage)
Membrane material
SS 304/304L, 316/316L or equivalent.
Other materials upon approval.
Fluid
Liquid Argon (LAr)
Outside reinforcement (Support structure)
Self standing steel enclosure. Might include embedded heaters
to prevent steel from freezing (Floor + Sides)
TPC size (with field cage and frame)
Width: 4,312 mm (Transvers to beam)
Length: 2 x 2,656 = 5,312 mm (Parallel to beam)
Height: 4,294 mm
Minimum clearance of TPC (Back)
1,200 mm (CPA bar to the tip of corrugation)
Minimum clearance of TPC (Front)
375 mm (CPA bar to the tip of corrugation *)
Minimum clearance of TPC (Sides)
375 mm (CPA bar to the tip of corrugation *)
Minimum clearance of TPC (Floor)
400 mm (CPA bar to the tip of corrugation *)
Depth of LAr above TPC
400 mm (Above the CPA frame)
Minimum depth of liquid argon
5,164 mm (From the floor)
Maximum static heat leak
15 W/m2 (Sides/Floor)
20 W/m2 (Roof)
Note (*): The TPC clearances are set to avoid high voltage breakdown
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David M, Michael G, Dimitar M, Joe H | SBND Cryostat Design
Oct 14, 2015
Cryostat requirements – 2
Parameter
Value
Vapor barrier
Stainless steel plates (part of support structure)
Insulation thickness
600 mm
Secondary barrier
GTT design (sandwiched within the insulation). Liquid tight.
Membrane thickness (GTT)
1.2 mm (assumed 2 mm to calculate external dimensions)
Corrugation height
70 mm
Minimum inner dimensions cryostat
(Same as last iteration)
5,202 mm (Transv) x 7,027 mm (Para) x 5,423 mm (H) *
(flat plate to flat plate)
Operating gas pressure
Positive pressure. Nominally 70 mbar (~1 psig)
Design Pressure
345 mbarg (~5 psig)
Membrane leak tightness
1E-6 mbar*l/sec
-
Penetrations
1 side penetration through the membrane at the lowest
possible/practical elevation for LAr circulation and
purification. Downstream of beam. Location and size TBD.
Lifetime
10 years (5 years of run + 5 years potential upgrade)
Thermal cycles
20 cool down and total warm-up
Note (*): the height is fine with either a flat metal plate without corrugations (invar or
similar) or corrugated membrane panels.
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David M, Michael G, Dimitar M, Joe H | SBND Cryostat Design
Oct 14, 2015
Outer structure requirements – 1
Parameter
Configuration
Vapor barrier
Minimum inner dimensions
Design Pressure
LAr + GAr load
Uplift force (top)
Additional loads
Seismic load
Penetrations
Maximum deflection towards
outside
Design code
Value
Self standing steel enclosure. Might include embedded heaters to prevent
air condensation on the outside of the veto (Floor + Sides).
6 mm SS 304L plates connected to the I-beams of the support structure
6,406 mm (Transv) x 8,231 mm (Para) x 6,627 mm (H) *
(flat plate to flat plate, inner of vapor barrier)
345 mbarg (~5 psig)
- 384 ton (Bottom)
- 200 ton (Long side)
- 148 ton (Short side)
- 126 ton (GAr)
- Loads transferred from the top plate down to the support structure
- Veto (2,500 kg each side wall, 2,00 front/back walls)
See SB DocDB n. 274
- 1 side penetrations from the inner membrane at the lowest
possible/practical elevation for LAr circulation and purification.
Downstream of beam. Exact location and size TBD.
- 4 side penetrations for GAr purge in insulation (2 In, 2 Out). Location
and size TBD.
50 mm (for veto)
Being discussed
Note: It has to fit inside the building leaving enough space for ES&H requirements, LAr pumps placement, etc.
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David M, Michael G, Dimitar M, Joe H | SBND Cryostat Design
Oct 14, 2015
Cryostat top requirements – 1
Parameter
Value
Roof configuration
Two metal plates reinforced with profiles/beams anchored to the outer
support structure to match an opening in the roof:
- One removable plate with TPCs hung underneath, containing all
penetrations for the TPC, light detection and laser calibration systems
(With the exception of the HV feedthroughs). If welded, provisions shall
be made to allow for removal and re-welding six (6) times.
- One fixed plate containing all the penetrations and services for the
cryostat and cryogenics and the TPC HV feedthroughs.
Dimensions
To match the cryostat and the DAB door for transportation of top
plate + TPC anchored underneath.
Plate Trusses non-wet material
Steel if room temperature.
SS 304/304L or equivalent if at cryogenic temperature.
Wet material
SS 304/304L, 316/316L or equivalent. Other materials upon approval.
Fluid
Liquid Argon (LAr)
Design Pressure
345 mbarg (5.0 psig)
Design Temperature
77 K (liquid Nitrogen temperature for flexibility)
Maximum allowable roof deflection
0.003 m differential between APA and CPA (*)
Pressure stability inside the tank
No requirement, as long as the roof deflection is within the limit. Same for
atmospheric pressure variations.
Note (*): This may require to mechanically decouple the TPCs from the top.
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David M, Michael G, Dimitar M, Joe H | SBND Cryostat Design
Oct 14, 2015
Cryostat top requirements – 2
Parameter
7
Value
Maximum static heat leak
20 W/m2 (Greater than sides/bottom to allow for penetrations, etc.)
Max vibration
No problem < 1 kHz
Worst is 100 kHz
Additional design loads
SBN DocDB n. 552
Seismic load
SBN DocDB n. 274
TPC anchors
SBN DocDB n. 552
Grounding plate
See Linda’s talk.
Lifting fixtures
Appropriate for positioning the top and the different parts that
constitute it.
Penetrations list, type, location
SBN DocDB n. 552
Clear space around each penetration
SBN DocDB n. 552
Lifetime
10 years (5 years of run + 5 years potential upgrade)
Thermal cycles
20 cool down and total warm-up
David M, Michael G, Dimitar M, Joe H | SBND Cryostat Design
Oct 14, 2015
Removable top plate list of penetrations
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David M, Michael G, Dimitar M, Joe H | SBND Cryostat Design
Oct 14, 2015
Removable top plate layout
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David M, Michael G, Dimitar M, Joe H | SBND Cryostat Design
Oct 14, 2015
Fixed top plate list of penetrations (sample)
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David M, Michael G, Dimitar M, Joe H | SBND Cryostat Design
Oct 14, 2015
Clear space around penetrations
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David M, Michael G, Dimitar M, Joe H | SBND Cryostat Design
Oct 14, 2015
Transportation/Access needs
• TPCs will be assembled and installed under the top plate in the DZero
Assembly Building (DAB):
– Available Height: 6,083 mm (per Joe H.)
– Available width: 5,790 mm.
• Current preliminary dimensions of Top plate + TPC:
– Height (including TPC): see next slide.
– Width: 5,304 mm.
• Need to add transportation equipment and design a support scheme for
transportation.
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David M, Michael G, Dimitar M, Joe H | SBND Cryostat Design
Oct 14, 2015
Height (from Joe H. Oct 14, 2015)
Cryostat and TPC height values 14 Oct 2015
Minimum cryostat
inner height 5423 mm
LAr fill fraction
5164/5423= .952
5% gas
ullage
Minimum distance
from the CPA to the
LAr level 400 mm
Currently 450 mm
Minimum LAr level
5164 mm
Bottom of TPC to seal
face of cryostat top
5063 mm
TPC and cryostat top height
5603mm
450mm
6053 mm
Too close to fit through
DAB door
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David M, Michael G, Dimitar M, Joe H | SBND Cryostat Design
CPA height
4194 mm
Minimum distance
from the CPA to the
peak of a 70 mm
membrane
corrugation 400 mm
Currently 450 mm
Oct 14, 2015
Summary
•
The inner dimensions of the membrane cryostat (flat plate to flat plate) are: 5,202
mm (Transverse) x 7,027 mm (Parallel) x 5,423 mm (Height).
•
Adding 600 mm of insulation and 2 mm of membrane (rounded for calcs), the
inner dimensions of the outer support structure are: 6,406 mm (Transverse) x
8,231 mm (Parallel) x 6,627 mm (Height).
•
Two top plates (one may be integral part of the cryostat):
– One fixed with all cryo penetrations + HV.
– One removable with the TPC hung from underneath and the TPC penetrations, laser
calibrations and light detection.
– Details of the in SBN DocDB n. 552.
•
14
During the design of the top plate, the limitations of the DAB door needs to be
taken into account to verify the available height and width.
David M, Michael G, Dimitar M, Joe H | SBND Cryostat Design
Oct 14, 2015