Prototype for DUNE detector will test new technology that can handle more neutrinos

Long before the Deep Underground Neutrino Experiment takes its first measurements in an effort to expand our understanding of the universe, a prototype for one of the experiment’s detectors is blazing new trails in neutrino detection technology.

DUNE, currently under construction, will be a massive experiment that spans more than 800 miles. A beam of neutrinos originating at the U.S. Department of Energy’s Fermi National Accelerator Laboratory will pass through a particle detector located on the Fermilab site, then travel through the ground to a huge detector at the Sanford Underground Research Facility in South Dakota.

The near detector consists of a set of particle detection systems. One of them, known as the ND-LAr, will feature a liquid-argon time projection chamber to record particle tracks; it will be placed inside a container full of liquid argon. When a neutrino collides with one of the particles that make up argon atoms, the collision generates more particles. As each particle created in the collision travels out of the nucleus, it interacts with nearby atoms, stripping off some of their electrons, leading to the production of detectable signals in the form of light and charge. ND-LAr is optimized to see both of these types of signals. DUNE scientists chose liquid argon for one of the near detector systems so that they can make direct, one-to-one comparisons when analyzing the results from both the ND-LAr and the far detector, which also relies on liquid argon for particle detection.

The prototype for ND-LAr received its name, the 2×2 prototype, because its four modules are arranged in a square. The final version of ND-LAr will feature 35 modules, each slightly bigger than those used for the prototype. Soon, the 2×2 prototype will be installed underground in the path of Fermilab’s NuMI neutrino beam for testing.

“We’re going to put this in what is currently the world’s most intense neutrino beam,” said Juan Pedro Ochoa-Ricoux, a professor at the University of California, Irvine who is co-leading the data analysis effort for the 2×2 prototype. “We’re going to be able to test our prototype under realistic circumstances.”

Sorting a flood of neutrinos

The 2×2 prototype, and eventually ND-LAr itself, will detect the neutrino beam close to its most intense point.

When a beam of protons from an accelerator collides with a target, it creates a spray of other charged particles that quickly decay into other particles, including neutrinos. The beam of charged particles used to generate neutrinos is tightly focused, but when this neutrino beam is created, they can no longer be guided or focused, since they have no charge. As the beam travels through space, the neutrinos spread out, and the beam becomes less dense.

“It’s a little bit like a flashlight: When you aim a flashlight at a wall, if you’re close to the wall, you see a little circle, but if you get away from the wall, the circle becomes bigger and bigger and bigger,” Ochoa-Ricoux said.

Because the near detector will be close to the source of the neutrino beam, it will pick up more neutrino interactions in a smaller space than the far detector will. This powerful influx of neutrinos presents some challenges for efficiently recording the neutrino interactions in ND-LAr. While the far detector might only pick up one neutrino at the time, the near detector will see many more neutrinos interacting.

“All these interactions occur virtually at the same time,” Ochoa-Ricoux said. “We need to be able to disentangle all of these interactions.”

Fortunately, researchers at the University of Bern and DOE’s Lawrence Berkeley National Laboratory have been working on new designs and technology for a liquid-argon detector more suited to this high density of neutrinos.

The team at the University of Bern developed a novel design for liquid argon neutrino detectors. Instead of just one big volume of liquid argon, this design divides the detector into modules.

The new design not only results in a shorter distance for stripped electrons to drift toward the detecting surface, but also provides a better understanding of where the neutrino interactions are happening. Making the modules smaller shows the light produced in a neutrino interaction in one particular unit, narrowing down its location.

A modular design also means that fewer interactions take place in each module. As a result, it’s easier to pair the detection of the light and the charged particles to understand the neutrino interaction. This kind of detector can more effectively handle lots of interactions happening in a short amount of time.

These two consequences of a divided detector make it ideal for ND-LAr, as this design allows for a more accurate three-dimensional picture of where a neutrino interaction happened, said Michele Weber, a professor at the University of Bern working on the prototype detector design and leading the ND-LAr effort.

“It is great to see a concept developed at our university finding application in DUNE through a collaboration with Fermilab,” Weber said. “One challenge we had to address in order to know which signal belongs to which interaction is to improve the 3D view of each interaction.”

Getting a clearer picture

Meanwhile, at Berkeley Lab, another team has created a new type of signal readout system that can address the massive amount of data expected in the near detector.

Traditionally, liquid-argon time projection chambers, or LArTPC, have used a series of layered wires across the side of the detector to catch the signal from stripped electrons that are released in an interaction between a neutrino and the argon. Combining the signals collected by the layers of wires, which provide a series of two-dimensional projections, supplies enough information to reconstruct a three-dimensional picture of the interaction.

However, when there are a lot of neutrino-argon interactions in the detector — a phenomenon called neutrino pileup — this readout system doesn’t provide as clear of a picture, said Brooke Russell, a Chamberlain fellow at Berkeley Lab working on the 2×2 prototype.

Instead, the readout system developed at Berkeley Lab uses a fully pixelated readout, which means each physical channel in the detector corresponds to one digital readout channel. Using this array of pixels directly shows the three-dimensional location of the interaction and can resolve all of the many neutrino interactions happening nearly simultaneously.

“This has major implications for the types of signals that we construct and the intensity of activity that we can be tolerant to,” Russell said. “With the DUNE near detector, for the first time, we’re in a regime where we have neutrino pileup. Such a readout is absolutely required in order to reconstruct the neutrino events.”

Putting 2×2 to the test

The modules for the prototype were built and tested at the University of Bern, then shipped to Fermilab and tested again before their installation. Preparations are underway for the prototype’s installation by the end of the year in order to test the neutrino detection when the NuMI beam turns back on this winter.

The experiment’s installation team will place the prototype detector in a cryogenically cooled container and sandwich it between two repurposed detector pieces from the retired MINERvA neutrino experiment at Fermilab. MINERvA measured neutrino interactions from 2010 until 2019.

As the ND-LAr prototype detector isn’t very big, it cannot measure the full path of some of the particles created when neutrinos interact with argon. Notable examples are muons, which typically travel for long distances before stopping. That’s where the old MINERvA detector components come into play. Using those components to track muons exiting the prototype detector, scientists can distinguish muons from charged pions, another type of subatomic particle.

Placing the prototype between the MINERvA segments also helps identify muons that are passing through but didn’t originate in the detector, distinguishing them from the muons coming from inside the detector as a product of neutrino interactions.

“We can use the MINERvA planes to help us track neutrinos that interacted in the rock upstream of the detector and made muons that went into the detector,” said Jen Raaf, director of the Neutrino Division at Fermilab who coordinates the 2×2 prototype project. “We’ll be able to connect the tracks to identify those [that didn’t originate in the detector] and get rid of them, because that’s not what we’re interested in.”

The MINERvA planes also allow the scientists to track particles created in neutrino interactions in the LArTPC, but which exit the argon volume before stopping. “MINERvA will allow us to track these exiting particles and measure their energy,” Raaf said, “so that we can get an accurate estimate of the neutrino’s energy when it interacted in the LArTPC.”

When the 2×2 prototype is tested in the neutrino beam, not only will it ensure that the prototype is working properly, but researchers can also perform neutrino physics experiments, Ochoa-Ricoux said.

Even though the full-blown DUNE experiment won’t start operating for several more years,” he said, “we’re already going to be producing some important physics results with this prototype.”

Some of these pre-DUNE experiments in the 2×2 prototype include studying the reactions between neutrinos and the argon, and measuring cross sections, or the likelihood of particle interactions.

Between the modular design and the pixel readout, ND-LAr will be unique among liquid argon neutrino detectors. This means that building and testing a prototype is crucial to ensuring that the innovative design works as expected. As a new piece of technology is built, scientists must test each step of the construction to demonstrate its capabilities, Weber said.

“ND-LAr has an atypical design,” Russell said. “We want to validate that some of the design principles that we think will work, will actually work.”

It’s also important that a prototype is built big enough to ensure that the final piece of equipment is possible to construct and install, Raaf said.

“Doing something on a smaller scale, but big enough that you would be able to identify difficulties in construction and assembly, is a really important step of all particle physics experiments,” she said. “You want something that’s big enough to experience the various things you have to do, like use a crane to pick it up and be able to move it in certain ways.”

The DUNE collaboration is organized into consortia that focus on different aspects of the project. The development of the 2×2 prototype is part of the ND-LAr Consortium, of which the University of Bern and Berkeley Lab are only two among dozens of institutions.

“All of those people are participating in this prototype at some level, to make sure that what they’ve envisioned for the full-sized thing actually works on a smaller scale and that we don’t need to tweak anything,” Raaf said. “Maybe we will, which is fine — that’s why we do prototypes. We meet weekly and discuss, how’s it going? What do we need to do next? What went well? What can we improve?”

For a task this big, collaboration between multiple institutions is necessary, said Weber, who serves as the lead of the ND-LAr Consortium. Between Fermilab’s neutrino beam, the University of Bern’s modular detector concept, Berkeley Lab’s readout technology, and the data processing and analysis taking place at many institutions, each collaborator in the ND-LAr Consortium brings its unique capabilities to bear on this project.

“These efforts are too big for one institution alone,” Weber said. “You talk to various people, and you share the load. It’s a challenge to work with a lot of people, but it’s the only way, and it’s nice to see different ideas come together successfully.”

Fermi National Accelerator Laboratory is supported by the Office of Science of the U.S. Department of Energy. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

The U.S. Department of Energy’s Fermi National Accelerator Laboratory hosted a ribbon-cutting ceremony on Nov. 6 to open “The Quantum Garage,” a new flagship quantum research facility. The 6,000-sq.-ft. lab was imagined, designed and built by the Superconducting Quantum Materials and Systems Center to unite scientific communities, industries and start-ups nationally and internationally to advance quantum information science and technology.

Senior officials attending the event included DOE Undersecretary for Science and Innovation Geri Richmond, Illinois Gov. J.B. Pritzker and Deputy Gov. Martin Torres, U.S. Rep. Bill Foster, members of the Illinois state legislature, the consul generals of U.K. and Italy, as well as leaders from other federal agencies, including NASA, federal labs, academia and industry from across the U.S. and the world.

“The SQMS Quantum Garage will enable the scientific community, including start-ups, academia and industry to advance quantum technology and science, and break through the difficult technical barriers, with increased access to cutting-edge scientific tools and equipment,” said DOE Under Secretary for Science and Innovation Richmond.

The facility features several newly commissioned, large dilution refrigerators capable of reaching cryogenic temperatures just a tick above absolute zero. The fridges host platforms developed by the SQMS collaboration for performing quantum computation, sensing, metrology and communications.

These quantum platforms include the first commercial quantum processor deployed on-premise at Fermilab; quantum memories and transducers based on novel approaches that leverage Fermilab’s world-leading technology expertise; quantum metrology tools for developing materials standards; and quantum sensors for fundamental physics, with the potential to discover dark matter and detect gravitational waves.

Each of these platforms and experiments further advance the collaborative efforts of the 34 SQMS partners across industry, academia and federal labs, including Ames National Laboratory, NASA, NIST, Northwestern University, Rigetti Computing, the Italian Institute of Nuclear Physics, the U.K. National Physics Laboratory and more.

“The SQMS Quantum Garage signals a new era in this field, and represents the best of our National Quantum Initiative,” said Gov. Pritzker. “SQMS will accomplish what few other can — building on Fermilab’s unique strengths in related accelerator technology and particle physics, and creating a global partnership which spans across academia, national labs and industry, and federal agencies to reach a new quantum frontier. I’m thrilled to see our state attract the best in quantum science, and I am committed to making Illinois the premier hub of quantum development.”

The new facility will also train the next generation of quantum computing scientists, engineers and support staff. Recently, this 360-degree research space was the core training ground for the SQMS Center-led U.S. Quantum Information Science School that launched this August. The SQMS Center has already trained hundreds of students and through new partnerships with minority-serving institutions and strategic partners in the state of Illinois, the new lab will be a crucial space for training a diverse quantum workforce.

“At today’s inauguration of the Quantum Garage, we celebrate important scientific and technological advancements made by SQMS during its first three years of existence and, at the same time, the innovations and breakthroughs to come in the field of quantum information science and technology,” said SQMS Center Director Anna Grassellino. “Today would not be possible without the Department of Energy, Fermilab and the hard work done by our staff within the SQMS Center who have built this collaborative space.”

SQMS is one of the five Department of Energy National Quantum Information Science Research Centers.

A recording from today’s event is available at https://cms.illinois.gov/agency/media/video/videos.html.

The Superconducting Quantum Materials and Systems Center at Fermilab is supported by the DOE Office of Science.

The Superconducting Quantum Materials and Systems Center is one of the five U.S. Department of Energy National Quantum Information Science Research Centers. Led by Fermi National Accelerator Laboratory, SQMS is a collaboration of more than 30 partner institutions — national labs, academia and industry — working together to bring transformational advances in the field of quantum information science. The center leverages Fermilab’s expertise in building complex particle accelerators to engineer multiqubit quantum processor platforms based on state-of-the-art qubits and superconducting technologies. Working hand in hand with embedded industry partners, SQMS will build a quantum computer and new quantum sensors at Fermilab, which will open unprecedented computational opportunities. For more information, please visit sqmscenter.fnal.gov.

Fermi National Accelerator Laboratory is America’s premier national laboratory for particle physics research. A U.S. Department of Energy Office of Science laboratory, Fermilab is located near Chicago, Illinois, and operated under contract by the Fermi Research Alliance LLC. Visit Fermilab’s website at https://www.fnal.gov and follow us on Twitter @Fermilab.

What is your new role at the U.S. Department of Energy’s Fermi National Accelerator Laboratory?

I’m the environmental program manager, and I’ve been here for three months. It’s really great. I feel so fortunate to be part of such a cohesive team who are learning from each other and supporting one another and have a lot of energy. My whole career has kind of culminated in this position — and it’s so exciting to be here.

How has your career led you to this position at Fermilab?

I’m a geologist and have spent most of my career in environmental consulting. I also worked with the state of Wisconsin as chief of the Petroleum Cleanup Fund, so I have experience as a regulator and got to see things from that compliance perspective. For my “midlife crisis,” I left the field, and I became a secondary science and English-as-a-second language teacher.

My father was a drilling engineer and managed water projects around the world, so groundwater protection and environmental compliance have been a focus throughout my life. I went back into consulting and had my own firm for a few years, representing municipalities and providing expert witness services for law firms. I started working for DOE projects back in 2018.

I took a tour of Fermilab in 2016, and I decided at that time that this is where I wanted to culminate my career, by working at Fermilab. I love the fact that it’s focused on research and discovery. I love that there are so many dynamic people who are exploring the universe and all the complex problems related to energy and dark matter. The physics part of Fermilab just geeks me out every day.

As the environmental program manager, what are your goals for this program?

My goal in the next few years is to integrate environmental management into every system. We cover a lot of aspects related to the environment, everything from air emissions, cultural resource management, the National Environmental Policy Act, groundwater, permits for water going into the City of Batavia wastewater treatment system, and hazardous waste. There are a lot of decisions that we have to make on site, and we are involved in making sure that Fermilab remains compliant with all of these.

One of my goals is to have people realize that the environmental program is here, not just to focus on compliance, but to be a part of the team that ensures the Fermilab mission continues in the most efficient and effective way possible. We really want to build those systems in so they’re a part of everyone’s thought process — so that people think: ‘What are the environmental requirements here? Who do I call? Let’s get the environmental team in. Let’s ask them questions.’ We want environmental management to be an integral part of everyone’s job, not a just second thought.

What projects are you working on right now?

We have a lot of projects going on, but right now I’d say we’re working on two big focuses.

We conduct an internal Environmental Management System assessment where we evaluate the EMS every three years. What we do is conduct interviews and review documentation. This EMS assessment will help us determine how we can enhance our system and how we can better communicate it to everyone in the laboratory. We’ve been able to expand our environmental department significantly, and with that we have tremendous opportunities to spend time building working relationships and training others. It’s really an exciting time for me to be here because I like that challenge!

Another issue we’re working on is an emerging contaminant called PFAS: per- and poly-fluoroalkyl substances. PFAS is ubiquitous; it’s everywhere. For example, it is in non-stick pans, fire extinguishers, sticky notes and other household items. It has a fluorine-carbon bond that is very difficult to destroy, and to dispose of it is incredibly costly.

DOE has an action plan, and part of it is to minimize use of PFAS substances on site, but there are areas where projects require its continued use. We are preparing best management practices to put into place. We’re determining where we could provide training and more explanation of what makes a PFAS substance different than anything else and how it needs to be handled a little bit differently.

What is the most challenging part of the work you are doing?

I’d say the most challenging part is that I want to understand everything that’s going on at Fermilab right now! I know it’s going to take years for me to understand the various aspects of this facility. Fortunately, the staff on the environmental team are great about anticipating and sharing the information I need to know.

What is the most rewarding part of your position?

The constant opportunity to geek out over the incredible science that we do here. That is by far the best. And also the endless camaraderie among everyone. I mean, everyone is just so available to help.

What do you do for fun outside of the lab?

I really like hiking and exploring, whether it’s in the city or in national parks.

My husband and I live on a farm in Wisconsin. So, I’m here during the week, and I go home on weekends. We have a small herd of llamas and goats, and they’re really fun.

Do you have any final words that you want people to know about your role?

I really want to help build a synergy throughout the laboratory. We’re here to work together to support the mission.

Fermi National Accelerator Laboratory is supported by the Office of Science of the U.S. Department of Energy. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

The U.S. Department of Energy’s Fermi National Accelerator Laboratory is pleased to announce that Rae Moss will serve as the senior director of the lab’s communication division. She began her role on Oct. 2, coming from Idaho National Lab, where she was the director of communications and external affairs and, most recently, the head of Pacific Northwest external engagement.

“It is an exciting time at Fermilab with the expansion of new facilities and the research that is advancing high energy physics,” said Moss. “I am excited to move the mission of the lab ahead with dynamic communications and stories telling the public about the exciting work being done here.”

In her role as Fermilab’s senior director of communication, Moss will oversee external, internal and digital communications, focusing on increasing awareness and engagement between Fermilab and its key stakeholders; education and public engagement; and conference management. 

She will be responsible for advancing the lab’s brand, reputation and mission as Fermilab is leading the development of the international Deep Underground Neutrino Experiment. DUNE is an experiment involving over 1,400 scientists and engineers from around the world who will research the behavior of neutrinos to understand why we live in a matter-dominated universe — in other words, why we are here at all.

Moss has more than 20 years of experience and leadership in communications and outreach at national labs and federal organizations. Prior to her leadership positions at INL, she served as the director of communications and external affairs at Mission Support Alliance, the provider for infrastructure, communications, utilities and security at the Hanford Site in Washington state and held communications positions at Pacific Northwest National Laboratory.

She has been an adjunct professor of marketing at Washington State University in Richland, Washington, and is currently completing her organizational development and communications doctoral degree at the University of Missouri. She earned her MBA in marketing from Duquesne University in Pittsburgh.

Fermi National Accelerator Laboratory is supported by the Office of Science of the U.S. Department of Energy. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.