From DOE’s Lawrence Berkeley National Laboratory (US): “Detector Technology Developed at Berkeley Lab Yields Unprecedented 3D Images Heralding Far Larger Application to Study Neutrinos”

From DOE’s Lawrence Berkeley National Laboratory (US)

May 13, 2021

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Bill Schulz

A LArPix sensor with 4900 pixels under testing at Berkeley Lab before shipment to the University of Bern [Universität Bern](CH) for installation. Credit: Thor Swift, Berkeley Lab.

An experiment to capture unprecedented 3D images of the trajectories of charged particles has been demonstrated using cosmic rays as they strike and travel through a cryostat filled with a ton of liquid argon. The results confirm the capabilities of a novel detector technology for particle physics developed by researchers at Lawrence Berkeley National Laboratory (Berkeley Lab) in collaboration with several university and industrial partners.

Groundbreaking in scale for this new technology, the experiment at University of Bern [Universität Bern](CH) – directed remotely because of the COVID-19 pandemic – demonstrates readiness for a far larger and more ambitious project: the Fermi National Accelerator Laboratory DUNE/LBNF experiment (US), said Berkeley Lab scientist and team leader Dan Dwyer.

In just a few short years, the Berkeley Lab team has turned an ambitious concept called LArPix (liquid argon pixels) into a reality, Dwyer said. “We have overcome challenges in noise, power consumption, cryogenic compatibility, and most recently scalability/reliability by transferring many aspects of this technology to industrial fabrication.”

DUNE is a major new science facility being built by the U.S. Department of Energy (DOE) to study the properties of subatomic neutrinos that will be fired off underground from an accelerator at DOE’s Fermi National Accelerator Laboratory (Fermilab) near Chicago, Dwyer explained. Neutrinos are extremely light particles that interact weakly with matter ­– something researchers would like to understand better in their quest to answer fundamental questions about the universe.

Neutrinos produced by the Fermilab accelerator will pass through a near detector, instrumented with LArPix, on the Fermilab site before moving on to complete their 700-mile journey at a deep underground mine in South Dakota.

LArPix is a leap forward in how to detect and record signals in liquid argon time projection chambers (LArTPCs), a technology of choice for future neutrino and dark matter experiments, Dwyer explained.

In a LArTPC, energetic subatomic particles enter the chamber and liberate or ionize electrons in the liquid argon. A strong, externally applied electric field drifts the electrons toward an anode side of the detector chamber where typically a plane of wires acts as sensitive antennae to read these signals and create stereoscopic 2D images of the event. But this technology is not enough to cope with the intensity and complexity of the neutrino events to be read for the DUNE Near Detector, Dwyer said.

“So, that’s where we at Berkeley Lab come in with this true 3D pixel readout provided by LArPix,” Dwyer said. “It will allow us to image DUNE neutrinos with high fidelity in a very busy environment.“

Using LArPix, he explained, the planes of wires are replaced with arrays of metallic pixels fabricated on standard electronic circuit boards, which can be readily manufactured. The low-power electronics, he said, are compatible with the demands of the cryogenic state of the liquid argon medium.

This latest achievement would not have been possible without the strong partnership with the ArgonCube Collaboration, a team of scientists focused on advancing LArTPC technology, centered at the University of Bern. For the Bern experiments, the researchers used a detector chamber with 80,000 pixels submerged in a ton of liquid argon at -330 degrees Fahrenheit. The system, he said, provided high fidelity, true 3D-imaging of cosmic ray showers as they traveled through the detector.

“This is a major milestone in the development of LArTPCs and the DUNE Near Detector,” said Michele Weber, Director of the Laboratory for High Energy Physics at the University of Bern who also serves as leader of the DUNE International Consortium responsible for building this detector.

“It’s vastly more complicated than anything that’s ever been built for LArTPCs,” said Brooke Russell, a postdoctoral fellow at Berkeley Lab and member of the LArPix team. With 80,000 channels, she said, the LArPix run at Bern far surpassed the previous state-of-the-art 15,000 channel LArTPC. “The level of complexity going from wires to pixels grew exponentially,” she said.

Partners from University of California at Berkeley (US), California Institute of Technology (US), Colorado State University (US), Rutgers University (US), University of California Davis (US), University of California Irvine (US), University of California Santa Barbara (US), University of Pennsylvania (US), and the University of Texas- Arlington (US) helped the researchers develop and test this much larger system.

For DUNE, Dwyer said, the system must scale to more than 10 million pixels that will sit in some 300 tons of liquid argon. He said this is doable both because of the modular nature of the detector chambers as well as the ability to tile LArPix boards made up of thousands of individual pixel detectors.

“This technology will enable the DUNE Near Detector to overcome signal pileup resulting from the high-intensity of the neutrino beam at the site,” Dwyer said. “It may also find use in the DUNE Far Detectors, other physics experiments, as well as non-physics applications,” he said.

At the DUNE Far Detectors, scientists will measure how the quantum flavor of the neutrinos changes in transit from the near detector.

By studying neutrinos, “we think we can learn something about the deeper mysteries of the universe – particularly such questions as why there’s more matter than antimatter in the universe,” Dwyer explained.

For DUNE to succeed, particle physicists “needed a level of thinking outside the box when it comes to detector technology,” Russell said. “For any breakthroughs in experimental particle physics of course you need novel ideas,” she added. “But if your hardware can’t deliver then you simply can’t make the measurement.”

This research is supported by the Department of Energy’s Office of Science, in part through the Office of Science Early Career Research Program.

See the full article here .


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Bringing Science Solutions to the World

In the world of science, Lawrence Berkeley National Laboratory (Berkeley Lab) (US) is synonymous with “excellence.” Thirteen Nobel prizes are associated with Berkeley Lab. Seventy Lab scientists are members of the National Academy of Sciences (NAS), one of the highest honors for a scientist in the United States. Thirteen of our scientists have won the National Medal of Science, our nation’s highest award for lifetime achievement in fields of scientific research. Eighteen of our engineers have been elected to the National Academy of Engineering, and three of our scientists have been elected into the Institute of Medicine. In addition, Berkeley Lab has trained thousands of university science and engineering students who are advancing technological innovations across the nation and around the world.

Berkeley Lab is a member of the national laboratory system supported by the U.S. Department of Energy through its Office of Science. It is managed by the University of California(UC) and is charged with conducting unclassified research across a wide range of scientific disciplines. Located on a 202-acre site in the hills above the UC Berkeley campus that offers spectacular views of the San Francisco Bay, Berkeley Lab employs approximately 3,232 scientists, engineers and support staff. The Lab’s total costs for FY 2014 were $785 million. A recent study estimates the Laboratory’s overall economic impact through direct, indirect and induced spending on the nine counties that make up the San Francisco Bay Area to be nearly $700 million annually. The Lab was also responsible for creating 5,600 jobs locally and 12,000 nationally. The overall economic impact on the national economy is estimated at $1.6 billion a year. Technologies developed at Berkeley Lab have generated billions of dollars in revenues, and thousands of jobs. Savings as a result of Berkeley Lab developments in lighting and windows, and other energy-efficient technologies, have also been in the billions of dollars.

Berkeley Lab was founded in 1931 by Ernest Orlando Lawrence, a University of California, Berkeley(US) physicist who won the 1939 Nobel Prize in physics for his invention of the cyclotron, a circular particle accelerator that opened the door to high-energy physics. It was Lawrence’s belief that scientific research is best done through teams of individuals with different fields of expertise, working together. His teamwork concept is a Berkeley Lab legacy that continues today.



The laboratory was founded on August 26, 1931, by Ernest Lawrence, as the Radiation Laboratory of the University of California, Berkeley, associated with the Physics Department. It centered physics research around his new instrument, the cyclotron, a type of particle accelerator for which he was awarded the Nobel Prize in Physics in 1939.

LBNL 88 inch cyclotron.

Throughout the 1930s, Lawrence pushed to create larger and larger machines for physics research, courting private philanthropists for funding. He was the first to develop a large team to build big projects to make discoveries in basic research. Eventually these machines grew too large to be held on the university grounds, and in 1940 the lab moved to its current site atop the hill above campus. Part of the team put together during this period includes two other young scientists who went on to establish large laboratories; J. Robert Oppenheimer founded DOE’s Los Alamos Laboratory(US), and Robert Wilson founded Fermi National Accelerator Laboratory(US).


Leslie Groves visited Lawrence’s Radiation Laboratory in late 1942 as he was organizing the Manhattan Project, meeting J. Robert Oppenheimer for the first time. Oppenheimer was tasked with organizing the nuclear bomb development effort and founded today’s Los Alamos National Laboratory to help keep the work secret. At the RadLab, Lawrence and his colleagues developed the technique of electromagnetic enrichment of uranium using their experience with cyclotrons. The “calutrons” (named after the University) became the basic unit of the massive Y-12 facility in Oak Ridge, Tennessee. Lawrence’s lab helped contribute to what have been judged to be the three most valuable technology developments of the war (the atomic bomb, proximity fuse, and radar). The cyclotron, whose construction was stalled during the war, was finished in November 1946. The Manhattan Project shut down two months later.


After the war, the Radiation Laboratory became one of the first laboratories to be incorporated into the Atomic Energy Commission (AEC) (now Department of Energy(US). The most highly classified work remained at Los Alamos, but the RadLab remained involved. Edward Teller suggested setting up a second lab similar to Los Alamos to compete with their designs. This led to the creation of an offshoot of the RadLab (now the Lawrence Livermore National Laboratory(US)) in 1952. Some of the RadLab’s work was transferred to the new lab, but some classified research continued at Berkeley Lab until the 1970s, when it became a laboratory dedicated only to unclassified scientific research.

Shortly after the death of Lawrence in August 1958, the UC Radiation Laboratory (both branches) was renamed the Lawrence Radiation Laboratory. The Berkeley location became the Lawrence Berkeley Laboratory in 1971, although many continued to call it the RadLab. Gradually, another shortened form came into common usage, LBNL. Its formal name was amended to Ernest Orlando Lawrence Berkeley National Laboratory in 1995, when “National” was added to the names of all DOE labs. “Ernest Orlando” was later dropped to shorten the name. Today, the lab is commonly referred to as “Berkeley Lab”.

The Alvarez Physics Memos are a set of informal working papers of the large group of physicists, engineers, computer programmers, and technicians led by Luis W. Alvarez from the early 1950s until his death in 1988. Over 1700 memos are available on-line, hosted by the Laboratory.

The lab remains owned by the Department of Energy(US), with management from the University of California(US). Companies such as Intel were funding the lab’s research into computing chips.

Science mission

From the 1950s through the present, Berkeley Lab has maintained its status as a major international center for physics research, and has also diversified its research program into almost every realm of scientific investigation. Its mission is to solve the most pressing and profound scientific problems facing humanity, conduct basic research for a secure energy future, understand living systems to improve the environment, health, and energy supply, understand matter and energy in the universe, build and safely operate leading scientific facilities for the nation, and train the next generation of scientists and engineers.

The Laboratory’s 20 scientific divisions are organized within six areas of research: Computing Sciences; Physical Sciences; Earth and Environmental Sciences; Biosciences; Energy Sciences; and Energy Technologies. Berkeley Lab has six main science thrusts: advancing integrated fundamental energy science; integrative biological and environmental system science; advanced computing for science impact; discovering the fundamental properties of matter and energy; accelerators for the future; and developing energy technology innovations for a sustainable future. It was Lawrence’s belief that scientific research is best done through teams of individuals with different fields of expertise, working together. His teamwork concept is a Berkeley Lab tradition that continues today.

Berkeley Lab operates five major National User Facilities for the DOE Office of Science(US):

The Advanced Light Source (ALS) is a synchrotron light source with 41 beam lines providing ultraviolet, soft x-ray, and hard x-ray light to scientific experiments.


The ALS is one of the world’s brightest sources of soft x-rays, which are used to characterize the electronic structure of matter and to reveal microscopic structures with elemental and chemical specificity. About 2,500 scientist-users carry out research at ALS every year. Berkeley Lab is proposing an upgrade of ALS which would increase the coherent flux of soft x-rays by two-three orders of magnitude.

The Joint Genome Institute (JGI) supports genomic research in support of the DOE missions in alternative energy, global carbon cycling, and environmental management. The JGI’s partner laboratories are Berkeley Lab, Lawrence Livermore National Lab (LLNL), DOE’s Oak Ridge National Laboratory(US)(ORNL), DOE’s Pacific Northwest National Laboratory(US) (PNNL), and the HudsonAlpha Institute for Biotechnology(US). The JGI’s central role is the development of a diversity of large-scale experimental and computational capabilities to link sequence to biological insights relevant to energy and environmental research. Approximately 1,200 scientist-users take advantage of JGI’s capabilities for their research every year.

The LBNL Molecular Foundry(US) [above] is a multidisciplinary nanoscience research facility. Its seven research facilities focus on Imaging and Manipulation of Nanostructures; Nanofabrication; Theory of Nanostructured Materials; Inorganic Nanostructures; Biological Nanostructures; Organic and Macromolecular Synthesis; and Electron Microscopy. Approximately 700 scientist-users make use of these facilities in their research every year.

The DOE’s NERSC National Energy Research Scientific Computing Center(US) is the scientific computing facility that provides large-scale computing for the DOE’s unclassified research programs. Its current systems provide over 3 billion computational hours annually. NERSC supports 6,000 scientific users from universities, national laboratories, and industry.

National Energy Research Scientific Computing Center (NERSC) at Lawrence Berkeley National Laboratory

The Genepool system is a cluster dedicated to the DOE Joint Genome Institute’s computing needs. Denovo is a smaller test system for Genepool that is primarily used by NERSC staff to test new system configurations and software.

PDSF is a networked distributed computing cluster designed primarily to meet the detector simulation and data analysis requirements of physics, astrophysics and nuclear science collaborations.


NERSC is a DOE Office of Science User Facility.

The DOE’s Energy Science Network(US) is a high-speed network infrastructure optimized for very large scientific data flows. ESNet provides connectivity for all major DOE sites and facilities, and the network transports roughly 35 petabytes of traffic each month.

Berkeley Lab is the lead partner in the DOE’s Joint Bioenergy Institute(US) (JBEI), located in Emeryville, California. Other partners are the DOE’s Sandia National Laboratory(US), the University of California (UC) campuses of Berkeley and Davis, the Carnegie Institution for Science(US), and DOE’s Lawrence Livermore National Laboratory(US) (LLNL). JBEI’s primary scientific mission is to advance the development of the next generation of biofuels – liquid fuels derived from the solar energy stored in plant biomass. JBEI is one of three new U.S. Department of Energy (DOE) Bioenergy Research Centers (BRCs).

Berkeley Lab has a major role in two DOE Energy Innovation Hubs. The mission of the Joint Center for Artificial Photosynthesis (JCAP) is to find a cost-effective method to produce fuels using only sunlight, water, and carbon dioxide. The lead institution for JCAP is the California Institute of Technology(US) and Berkeley Lab is the second institutional center. The mission of the Joint Center for Energy Storage Research (JCESR) is to create next-generation battery technologies that will transform transportation and the electricity grid. DOE’s Argonne National Laboratory(US) leads JCESR and Berkeley Lab is a major partner.