LBNE's Liquid Argon Prototype Cryostat
The development of the LBNE liquid argon time projection chamber (LArTPC) Far Detector design includes a prototyping program to ensure that the detector cryostat will be viable and to test some important aspects of the design.
The detector design, changed in mid-2012 as part of the LBNE reconfiguration effort, is planned to consist of two membrane cryostats side-by-side, each of volume 5,000 tons and dimensions approximately 16 m by 16 m by 29 m -- many times larger than any existing liquid argon detector. The most significant issue to resolve is whether a membrane cryostat of this
size can achieve and maintain the required liquid argon purity level. When the detector is running, the ionization electrons resulting from particle interactions in the liquid argon need to reach the wire planes to create the signals. Impurities reduce the distance they can travel.
The Liquid Argon Purity
Demonstrator (LAPD) is an off-project (non-LBNE)
prototype being built as part of a development program at Fermilab to study the scaling of LArTPCs to kiloton sizes. LAPD is the first system to achieve the necessary electron lifetimes for long drift distances without prior evacuation of the cryostat.
Building on this success, the LBNE Project had plans in place to develop two membrane-cryostat prototypes of progressively larger sizes – 35 tons and 1,000 tons – to confirm that at larger scales the required
LAr purity can still be achieved without initial evacuation of the cryostat. The larger, 1,000 ton prototype has been cancelled, therefore the 35-ton cryostat will be used for a wider testing program than originally planned. In addition, a smaller installation prototype will be built and used to test construction and installation techniques
The 35-ton Prototype
A schematic of LBNE's 35-ton liquid argon prototype cryostat (green box at lower left) located next to the Liquid Argon Purity Demonstrator (LAPD, orange cylinder at upper right) in building PC-4 at Fermilab.
Credit: D.Montanari
The LBNE project has contracted with the Japanese company IHI to help LBNE build the smaller 35-ton prototype
membrane cryostat at Fermilab.
This unit, of approximate dimensions 4 by 4 by 5 1/2 cubic meters, is currently under construction and will be made operational in the 2012-2013 time frame at Fermilab's PC-4 facility, where LAPD is located. The prototype has been designed to share many components with LAPD, enabling the two programs to run in parallel. In particular, the prototype will share LAPD's liquid-argon purification system.
This 35-ton unit will be used to demonstrate the membrane-cryostat technology
(thermal performance, leak-tightness) in addition to the achievability of adequate LAr purity during cryostat-filling, purification and maintenance. A further testing program is under development, and will likely include tests of the TPC, the electronics and the photon-detection system.
More images (in reverse chronological order)...
October 25, 2012
"As of this morning the 35 ton cryostat has been declared leak tight,
passing the ammonia leak check (twice) without a single leak. During
the dye penetrant test which proceeded the ammonia, about 30 spots had to
be touched up. There are cleanup activities on-going today.
Plate B is not included in this as this is Fermilab responsibility.
Terry Tope and David Montanari will coordinate the next assembly steps.
IHI will be headed home on Saturday!"
-- Barry Norris
August 27, 2012
Continuing from previous week installing the second layer of insulation. Note that wall sections are in place.
Fermilab employee Ron Davis is holding a panel section and
getting ready to assist with putting it in place. Also shown is IHI
employee Kanno.
Credit: D. Montanari
August 24, 2012
The following photo shows the second layer of insulation being installed.
The floor section is installed and
personnel are preparing for liquid PUF application between panel sections.
Pictured are Kubinski, Davis, Montanari (FNAL) and Kanno (IHI).
Credit: B. Norris
August 1, 2012
From David Montanari: "Today we finished the inspection of the vapor barrier and started the installation of the insulation."
Empty, fully leak-tested vapor barrier in tank
Credit: D. Montanari
August 1, 2012
From David Montanari: "Today we finished the inspection of the vapor barrier and started the installation of the insulation (2nd photo)."
Technicians begin installing insulation over the vapor barrier
Credit: D. Montanari
July 19, 2012
From Barry Norris: "This morning the Vapor barrier welding was finalized... As (we)
finished those small things today we have begun two other tasks: 1)
Attaching piping/tubing system used for ammonia test of VB and 2)
Training of Fermilab technicians for insulation inspection."
TD technician Ryan Mahoney welds anchor on one of long VB panels of the floor.
Credit: B. Norris
July 16, 2012
Last week technicians were still preparing vapor barrier panels (first photo below); holes have been cut to fit the panels over the anchoring rods extending from the wall. The holes are sealed after the panels are installed (second photo below). Once a hole has been sealed and checked, the technicians write "OK" next to it. The vapor barrier has been installed on all four walls; the team expects to install the floor panels this week. The next step will be to leak-check the system.
An IHI technician prepares a vapor barrier panel for installation.
Credit: B. Norris
The vapor barrier installed on a cryostat wall.
Credit: B. Norris
June 21, 2012
The photo below shows the carbon steel sheets welded to angles embedded in the concrete. These sheets will form a hermetic liner that will act as a vapor barrier to keep moisture from entering the insulation layer, which goes on next. The stainless steel plates resting on the wood blocks on top of the wall will be welded to the angles at the top to cap the wall. The yellow tube carries exhaust from a fan used during the welding process.
Technician Ron Davis working in the tank.
Credit: T.Tope
June 4, 2012
The concrete work is complete.
In back, left to right, Fermilab engineers Terry Tope, Barry Norris and David Montanari. In front, contractors Youhei Saitou, Michitaka Furikoma and Ryuzzo Kanno from IHI; they are on-site for several weeks to supervise construction of the prototype cryostat.
Credit: Reidar Hahn
May 24, 2012
From Bruce Baller (manager of the LBNE Liquid Argon Far Detector subproject): "(Physicist) Alan Hahn has agreed to coordinate the activities in the 35-ton cryostat prototype along with (cryogenic engineers) Terry Tope and David Montanari... We are considering expanding the scope of the 35-ton prototyping program – specifically to track cosmic rays with a reduced-scale TPC and to test light collection schemes. Alan has agreed to coordinate these potential activities as well. The reduced scale prototype APA being constructed by the folks at the University of Wisconsin Physical Sciences Laboratory is a candidate for use in the 35-ton TPC. (See
doc #5970 for pictures and the current status.) Oleg Prokofiev has an alternate APA design. A small scale prototype is shown below under construction at Lab 6.
Small scale prototype anode plane assembly (APA) under construction at Fermilab.
May 18, 3pm CDT
They (the forms) are all off now. And the samples are by the tank." --Terry Tope
Credit: T.Tope
May 18, 12pm CDT"Yesterday the concrete was poured for the 35 ton and this morning the forms are being taken off ... The decision to remove was made in concert by FESS engineers and contractor. The remaining forms will be removed before the end of the morning ... Later next week they (the contractors from IHI) will be here and training for constructing the membrane cryostat will begin." --Barry Norris
Credit: B.Norris
Credit: B.Norris
As of May 14, the concrete forms and rebar have been installed.
Entire vessel with concrete and rebar
Credit: T. Tope
Close-up showing a spacer that places the rebar work a uniform distance (2 in) away from the form which will be the inside surface of the concrete.
Credit: T.Tope
During the week of April 30 the wall reinforcement was nearly completed. This week (of May 7) we are preparing the formwork for the concrete and the embedded angles for attachment of the vapor barrier and cryostat lid. We expect to pour concrete by the end of this week.
May 4: Structural support for the walls
Credit: D. Montanari
April 24: "I took pictures as the tech and welder were joining the walls together this morning. The fit up is very nice and square." -- Russ Rucinski
Credit: R.Rucinski
April 17: The first concrete is poured! Credit: B.Norris
As of mid-April 2012, a contractor has begun construction of the structural concrete support for the 35-ton membrane cryostat. The photo below shows the steel reinforcing for the concrete base of the tank laid out in the PC-4 tunnel.
April 13: The steel reinforcing for the concrete base of the tank is laid in place.
Credit: T.Tope
April 17: The first concrete is poured! Credit: B.Norris
The concrete work should be complete by early May. Soon after that, the cryostat vendor (IHI) will send out a team to supervise the assembly of the cryostat by Fermilab engineers, technicians and welders. This is expected to take 6-8 weeks to complete.
