Building a home for the world’s largest neutrino detector

Why is the world around us made of solid matter when prevailing theories of physics predict an equal amount of antimatter? What can neutrinos, the mysterious particles that pass through our bodies in the trillions every second, tell us about the history and future of the universe? These questions lie at the heart of the planned Deep Underground Neutrino Experiment (DUNE), a major international collaboration hosted by Illinois physics research center Fermilab.

For the third post in a series exploring the project and the complex being built to house it, we spoke with Josh Yacknowitz, Arup’s design project manager for the buildings, site, and infrastructure components of the Far Site detector in Lead, South Dakota.

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Give me an overview of the project and Arup’s work on it.

The project is a large program to develop the world’s largest neutrino detector. DUNE is the actual experiment portion of this project, and the facility that will house DUNE is called the Long Baseline Neutrino Facility (LBNF).

The project is taking place at two sites in two physical locations. One is a neutrino detector in South Dakota; that’s called the far detector, or the Far Site. Then there’s a near site detector at Fermilab, near Chicago, referred to as the Near Site.

Fermilab Wilson Hall

Fermilab Wilson Hall

Within those sites there are principally two streams of collaboration. One is the experiment itself, which is an international collaboration between a number of countries, academic institutions, and research organizations. The US Department of Energy (DOE) and the European Organization for Nuclear Research (CERN) are the key collaborators, with contributions and support from over 140 laboratories and universities in 27 countries. That group is designing the actual detectors of cells, which are one-off, custom-built pieces of apparatus. Fermilab, which is one of the DOE’s National Laboratories, is hosting the project.

The other side of the project, called the Conventional Facilities, includes everything required to house the experiment: underground excavation, structural requirements and building envelopes, power and data, thermal utilities, water, air — all the things that these facilities need in order to operate.

Arup, along with our collaborating partners, is designing the Conventional Facilities for the Far Site in South Dakota. The location is an existing facility called the Sanford Underground Research Facility, or SURF. It’s an old gold mine that was decommissioned early this century, and then portions were turned over to the State for scientific use.

Surface facilities at SURF

Surface facilities at SURF

How is this different than other projects that building engineers typically work on?

This is very different from a regular aboveground building project. It’s actually more of a civil infrastructure project for us, due mostly to the fact that it’s deep underground. It’s infrastructure you would normally see in a mine or a very deep underground civil facility.

What does that mean in practice? At the most basic level, how would you characterize the difference between a buildings project and a civil infrastructure project?

A buildings project is really an envelope that sits aboveground, for the most part. It could have various uses, but it’s generally an aboveground structure. The codes that govern that type of construction are very well established and prescriptive in many ways.

For underground work it’s much different. There is no one clear code that governs for different types of underground use. There are certain codes that are promulgated by federal and local government agencies — for example, codes that govern mine operations. There are underground tunneling codes. There are codes for things like rail infrastructure. But you really have to pull together codes and best practices from a number of different sectors for a facility like this. It’s going to house people who are not miners; they’re researchers. They’re not accustomed to a deep underground environment. So we have to bring in some of the codes and safety standards that we normally use aboveground in order to make the underground areas a secure environment.

How did that process look?

That actually started back in the days when we were working on a project called DUSEL at the same site. That was a different project altogether, run by the National Science Foundation, but it also involved reconfiguring the existing mine works to support new underground laboratories and experiments. During that period, our code and fire-safety people took a long look at the various prevailing codes and standards to come up with a life-safety approach that would take the project from construction all the way through operation. We collaborated closely with the experts at the DOE, our mining consultants, and the experts at South Dakota Science and Technology Authority who manage the SURF site.

In a normal building project, the local building authority reviews your design for compliance. How does that look in a project like this, where you’re defining the codes as you go along?

That’s a good question. Similar to the process of defining the codes and determining the right standards to use, figuring out who would serve as the authority having jurisdiction, or AHJ, was not straightforward. There’s actually more than one AHJ here. There is the local City of Lead, which functions as the local building department and plan approval agency. We have been working with them, presenting the design to their team and preparing variance requests, keeping them in the loop throughout the process. Then there’s the DOE itself, because the DUNE/LBNF Far Site will be a DOE facility. They have their own standards for construction and operation that we have to comply with. Any approvals regarding life safety and many other aspects of the design have to be reviewed and approved by the DOE.

Were the engineering solutions developed for this project unique across the board, or were some things like, “Oh, we’ve done basically the same thing for subway projects, so we can translate that fairly easily”?

We are able to use some of our expertise from deep underground tunneling, from underground rail infrastructure, from other science facilities and energy facilities. But for the most part, we didn’t make decisions alone. We worked very closely with the client and the facility, because they know the specific kinds of underground operations this project requires and they know the site. So it’s very much a balanced collaboration between Arup, the broader subconsultant team, and the client.

What parts have you found most interesting?

The fire/life-safety aspect is one. There are quite a few challenges, including large-scale cryogen storage in relatively tight confines, ongoing construction operations while occupants are present, limited avenues of egress from the underground areas, and the sheer depth — nearly a mile below the surface. Our team has come up with an approach that I think other similar facilities around the world could probably look to as a good example of a multilevel life-safety strategy in a deep underground environment.

The collaboration with the science team has also been very interesting. What they’re trying to build is basically a large bespoke machine that has unique risks and challenges, not only from a design perspective but also from a constructability perspective. How do you build these huge liquid-argon chambers to house the neutrino detector underground? They’re each the size of a small ship, and there are four of them.

Prototype LBNF liquid argon chamber

Prototype LBNF liquid-argon chamber

It’s very similar to the concept of building a ship in a bottle, because the only access to the underground area is through some very space-constrained shafts and tunnels. So helping the science team realize its vision has been a terrific engineering and logistical challenge. This is equipment that you would not normally see anywhere else. The people who are designing — really, inventing — this stuff as they go, they’re a quite diverse team of scientists, engineers, project managers, technicians, and specialists. We’ve gotten quite an education working with them.

 

Questions or comments for Josh Yacknowitz? Contact joshua.yacknowitz@arup.com.

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