DUNE scientists receive NSF grant to tackle mass production of detector components for massive neutrino experiment

How can you build 150 particle detector assemblies in less than three years if the completion of one assembly takes almost two months?

This is one of the big questions that scientists and engineers working on the international Deep Underground Neutrino Experiment have to answer to meet the ambitious goal of starting data taking in 2026. And the National Science Foundation just awarded a $1.6 million grant to four U.S. universities to develop the plan.

“Building an experiment of this scale requires years of research and development,” said Denise Caldwell, director of NSF’s Division of Physics. “We are pleased that this award will enable NSF collaborators to contribute to the planning of this truly international effort.”

While this is an NSF planning award for DUNE, the foundation has a long history of investments in major particle physics experiments, including research to uncover the mysteries of neutrinos.  NSF is the primary funding source of the IceCube Neutrino Observatory, located at the South Pole. The IceCube collaboration recently announced the first evidence of a source of high-energy cosmic neutrinos, giving us a more complete understanding of the universe.

The NSF grant for DUNE expands the foundation’s pioneering and significant investments in liquid-argon neutrino detectors and physics, including early investments in the ArgoNeuT, MicroBooNE and Short-Baseline Near Detector experiments.

DUNE, supported by the U.S. Department of Energy Office of Science and hosted by the DOE’s Fermilab, will use four gigantic particle detector modules filled with a total of 70,000 tons of liquid argon to look for tracks created by neutrinos to learn more about these elusive particles and the role they play in the universe. A crucial building block of these modules are large, rectangular frames with four layers of wires on each side, called anode plane assemblies. Each APA comprises 24,000 meters of wire, wound in straight lines to record the signals created by neutrino collisions in liquid argon.

Over the past two years, DUNE collaborators have built six of these APAs, each about 6 meters long and 2.3 meters wide, for a prototype detector the size of a two-story building, assembled at CERN. The final DUNE detectors, to be installed a mile underground at the Sanford Underground Research Facility in South Dakota, each will be 20 times larger. DUNE will need 300 APAs: half of them are expected to be built by a consortium of universities at Daresbury Laboratory in the UK, which already manufactured modules for the prototype at CERN; and the other half is expected to be built at facilities in the United States.

Now with support from the NSF, scientists and engineers from the University of Chicago, Yale, Syracuse and the Physical Sciences Laboratory at the University of Wisconsin are taking the lead to finalize the design of the APAs for DUNE and figure out how a broad consortium of U.S. universities—including many more institutions than the four receiving the initial NSF grant—could collectively build 150 APAs and ship them to South Dakota for installation underground.

“Once we have finalized the design and production plan, we will submit a proposal from a broad consortium of US universities to build the 150 APAs,” said University of Chicago’s Ed Blucher, who is the lead investigator on the NSF grant and co-spokesperson of the DUNE collaboration. “It will secure a leading role for NSF-supported university groups in constructing and ultimately in extracting physics from DUNE.”

The four institutions have extensive expertise in the design and production of wire planes for liquid-argon neutrino detectors, starting more than a decade ago.

“Now it is the technology of choice for many neutrino experiments,” said Bonnie Fleming, who served as the founding spokesperson for the ArgoNeuT and MicroBooNE experiments. “At Yale’s Wright Lab, we are winding wire planes for the Short-Baseline Near Detector at Fermilab. This effort is led by Syracuse and funded by the NSF, and students and postdocs from collaborating institutions are engaged in the process.”

The four institutions also have facilities that are big enough to set up the large assembly lines for the wiring and mass production of the APAs. In fact, the Physical Sciences Laboratory built four of the six APAs installed in the first DUNE prototype detector at CERN.

“There are not many institutions that have facilities with enough floor space for this kind of work,” Blucher said. “The NSF grant allows us to figure out how to put the APA production facilities into existing buildings, how to run those factories, how to integrate students and postdocs into the project, and how to plan for the work flow.”

So how do you produce 150 APAs in less than three years?

“Setting up multiple assembly lines and increasing the efficiency of winding each APA are part of the answer,” Blucher explained. “Ultimately, the assembly of each APA must be faster while maintaining superb quality control.”

The CMS experiment, which studies particle collisions at the Large Hadron Collider at CERN in Switzerland, is heading into a new era of research under the guidance of Fermilab scientist Patty McBride, one of two incoming deputy spokespersons.

She begins her two-year term on Sept. 1, serving in the role with Luca Malgeri of CERN. She will serve as deputy to incoming CMS spokesperson Roberto Carlin, INFN researcher and professor at the University of Padua, who concludes his term as deputy spokesperson.

McBride says that her love for physics began in eighth grade, when her mom gave her a book on particle accelerators, sparking her interest in investigating the subatomic world. After studying physics in college at Carnegie Mellon, she received her doctorate at Yale University and a postdoc at Harvard University. She started at Fermilab in 1994 and worked on a number of experiments and in various leadership positions. In 2005, she joined the CMS collaboration, working as head of the CMS Center at Fermilab from 2012 to 2013 and, later, as U.S. CMS operations program manager. In 2014, she became head of the Fermilab Particle Physics Division, where she served for four years.

“Patty is ideally suited to be one of the leaders of the international CMS collaboration since she brings deep experience in many aspects of particle physics,” said Joel Butler, Fermilab scientist and outgoing CMS spokesperson. “She possesses excellent judgement and problem-solving skills and the ability to inspire people to work together toward common goals.”

The giant CMS detector records particle collisions at the Large Hadron Collider to help scientists better understand the smallest constituents of our universe. In 2012, CMS co-discovered, along with the LHC’s ATLAS experiment, the long-sought-after Higgs boson, which led to a Nobel Prize in 2013 for the theorists who proposed it. The 4,000-strong CMS collaboration is now taking precise measurements of properties of the Higgs boson and searching for new physics, such as particles that could make up dark matter.

As deputy co-spokesperson, McBride will push to publish new physics results from the most recent LHC run and to prepare the experiment for the next run. She will also help direct the project to upgrade the detector to handle the higher-intensity collisions that will emerge from a revamped LHC, to come online in 2026. The new and improved High-Luminosity LHC, as it is called, will crank up the number of particle collisions to five to seven times its current rate and generate 30 times the data CMS has collected so far.

“CMS’s upgrades will prepare the detector and its instruments for the avalanche of data from the collisions once the LHC is upgraded,” McBride said.

McBride says she’s excited to help lead CMS into the next phase of its life and to work with an international collaboration from over 40 countries.

“I’m looking forward to working with such a large group of scientists from all over the world who will push CMS to improve,” McBride said. “It’s a privilege to be a part of a group that made such an important discovery in 2012, and it will be a privilege to help lead them to further discoveries.”

On Oct. 1, Fermilab and University of Chicago scientist Rich Kron begins his three-year term as director of the Dark Energy Survey, or DES, hosted by Fermilab. Fellow Fermilab scientist Tom Diehl will serve as deputy director.

From 2003-2008, Kron was director of the Sloan Digital Sky Survey, an astronomical survey in which Fermilab was heavily engaged until 2008. In 2010, he stepped into the role of DES deputy director. Now, as incoming director, he succeeds Fermilab and University of Chicago scientist Josh Frieman, who became head of the Fermilab Particle Physics Division earlier this year.

The Dark Energy Survey is a multinational, collaborative effort to map hundreds of millions of galaxies and stars to better understand dark energy, the phenomenon behind the increasingly rapid expansion of the universe. Using a powerful camera installed on a telescope on a Chilean mountaintop, DES researchers are creating detailed maps of the southern sky to uncover patterns in the distribution of celestial objects that reflect — or reveal — the impact of dark energy on the formation of structure in the universe. They are also discovering and measuring properties of several thousand supernovae —distant exploding stars — to chart dark energy’s influence on the history of cosmic expansion. The data will help researchers narrow in on dark energy’s nature.

As the new DES director, Kron will lead the 400-strong collaboration through its final data-taking season, which runs from September 2018 to January 2019.

“I’m honored to be given the opportunity to lead the Dark Energy Survey to the conclusion of its operations and the production of the final science results,” Kron said. “My predecessor Josh Frieman capably led the collaboration through the past eight years, and I have learned a lot from him.”

Each season of observation — a total of six for DES — adds more and more data, increasing the survey’s sensitivity to distant galaxies. In 2019, the collaboration will have amassed its full data collection.

“We’ll have the entire data collection packaged together and can write the final scientific papers. We’ll make sure everyone is engaged and gets the opportunity to take advantage of this huge effort,” Kron said.

“Rich is an internationally recognized astronomer who brings a wealth of experience and expertise to this role,” Frieman said. “He has done an excellent job as DES deputy director and will be a strong leader for DES as it heads into its last months of data taking and its golden years of science analysis.”

And Tom Diehl, incoming DES deputy director, has been with the collaboration since its early years. He worked on the construction of the camera used for DES and has also served as DES operations scientist since 2012.

“It’s an honor for Rich to ask me to be deputy director. It will be my pleasure to do my best to help the collaboration and Rich,” Diehl said. “We have a lot of exciting work to do.”

Both look forward to “getting the science out,” Kron said, sharing the findings of the forefront experiment they’ve helped advance for several years.

“DES is on a good track thanks to the efforts of many other colleagues at Fermilab and elsewhere, and I look forward to working with this great team,” Kron said.

Editor’s note: The following news release about the discovery of a long-sought decay of the Higgs boson is being issued by the U.S. Department of Energy’s Fermi National Accelerator Laboratory on behalf of the U.S. scientists working on the LHC. Fermilab serves as the U.S. hub for the CMS experiment at the LHC and the roughly 1,000 U.S. scientists who work on that experiment, including about 100 Fermilab employees. Fermilab is a Tier 1 computing center for LHC data and hosts a Remote Operations Center to process and analyze that data. Read more information about Fermilab’s role in the CMS experiment and the LHC. 

Today at CERN, the Large Hadron Collider collaborations ATLAS and CMS jointly announced the discovery of the Higgs boson transforming into bottom quarks as it decays. This is predicted to be the most common way for Higgs bosons to decay yet was a difficult signal to isolate because background processes closely mimic the subtle signal. This new discovery is a big step forward in the quest to understand how the Higgs enables fundamental particles to acquire mass.

After several years of refining their techniques and gradually incorporating more data, both experiments finally saw evidence of the Higgs decaying to bottom quarks that exceeds the 5-sigma threshold of statistical significance typically required to claim a discovery. Both teams found their results were consistent with predictions based on the Standard Model.

“The Higgs boson is an integral component of our universe and theorized to give all fundamental particles their mass,” said Patty McBride, distinguished scientist at the U.S. Department of Energy’s Fermi National Accelerator Laboratory and recently elected as one of the deputy spokespeople of the CMS experiment. “But we haven’t yet confirmed exactly how this field interacts — or even if it interacts — with all the particles we know about, or if it interacts with dark matter particles which remain to be detected.”

Higgs bosons are produced in only roughly one out of a billion LHC collisions and live only a tiny fraction of a second before their energy is converted into a cascade of other particles. Because it’s impossible to see Higgs bosons directly, scientists use these secondary particle decay products to study the Higgs’s properties. Since its discovery in 2012, scientists have been able to identify only about 30 percent of all the predicted Higgs boson decays. According to Viviana Cavaliere, a physicist at DOE’s Brookhaven National Laboratory who works on the ATLAS experiment, finding the Higgs boson decaying into bottom quarks has been priority number one for the last several years because of its large decay rate.

“Theory predicts that 60 percent of Higgs bosons decay into bottom quarks,” said Cavaliere, who is also using this process to search for new physics. “Finding and understanding this channel is critical because it opens up the possibility for us to examine the behavior of the Higgs, such as whether it could interact with new, undiscovered particles.”

The Higgs field is theorized to interact with all massive particles in the Standard Model, the best theory scientists have to explain the behavior of subatomic particles. But many scientists suspect that the Higgs could also interact with massive particles outside the Standard Model, such as dark matter. By finding and mapping the Higgs bosons’ interactions with known particles, scientists can simultaneously probe for new phenomena.

“A fraction of Higgs bosons could be producing dark matter particles as part of their decay,” said Giacinto Piacquadio, a physicist at Stony Brook University who co-led the Higgs-to-bottom-quarks analysis group. “Because the decay of the Higgs boson to bottom quarks is so common, we can use it to put constraints on potentially invisible decays as well as use it to probe for new physics directly.”

Even though this decay is the most popular path, spotting it in the experimental data was no walk in the park. Every proton-proton collision at the LHC produces a splattering of subatomic byproducts, one of the most common being bottom quarks. These bottom quarks then quickly decay into other kinds of particles, leaving behind vast showers of particles in the detectors. Tracing these particle showers back to two bottom quarks (and then figuring out which ones came from a Higgs boson) is extremely delicate and labyrinthine work.

“Being able to identify and isolate bottom quarks in the experimental data is a huge challenge and required precise detector calibration and sophisticated b-quark tagging,” Piacquadio said. “We were only able to do these analyses thanks to years of work that came before.”

To spot this process, the ATLAS and CMS collaborations each combined data from the first and second runs of the LHC and then applied complex analysis methods to the data.

“Finding just one event that looks like two bottom quarks originating from a Higgs boson is not enough,” said Chris Palmer, a scientist at Princeton who worked on the CMS analysis. “We needed to analyze hundreds of thousands of events before we could illuminate this process, which is happening on top of a mountain of similar-looking background events.”

According to Palmer, these deceptive background events made the analyses almost impossible to perform based on isolated bottom quarks alone.

“Luckily, there are a few Higgs production mechanisms that produce identifiable particles as byproducts,” Palmer said. “We used these particles to tag potential Higgs events and separate them out from everything else. So we really got a two-for-one deal with this analysis because not only did we find the Higgs decaying to bottom quarks, but we also learned a lot about its production mechanisms.”

The next step is to increase the precision of these measurements so that scientists can study this decay mode with a much greater resolution and explore what secrets the Higgs boson might be hiding.

More than 1,700 scientists, engineers and graduate students from the United States collaborate on the experiments at the LHC, most of them on the CMS and ATLAS experiments, through funding by the Department of Energy Office of Science and the National Science Foundation. Brookhaven National Laboratory serves as the lead national laboratory for participation in the ATLAS experiment, and Fermi National Accelerator Laboratory serves as the lead national laboratory for participation in the CMS experiment.

CERN, the European Organization for Nuclear Research, is the world’s leading laboratory for particle physics. It has its headquarters in Geneva. At present, its member states are Austria, Belgium, Bulgaria, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Israel, Italy, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Spain, Sweden, Switzerland and the United Kingdom. Cyprus, Slovenia and Serbia are associate members in the pre-stage to membership. India, Lithuania, Ukraine, Turkey and Pakistan are associate members. Japan, the Russian Federation, the United States of America, the European Union, JINR and UNESCO have observer status.

Fermilab is America’s premier national laboratory for particle physics and accelerator 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 www.fnal.gov and follow us on Twitter at @Fermilab.

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The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering. In fiscal year (FY) 2018, its budget is $7.8 billion. NSF funds reach all 50 states through grants to nearly 2,000 colleges, universities and other institutions. Each year, NSF receives more than 50,000 competitive proposals for funding and makes about 12,000 new funding awards.