Wichita State physicist studies the mysteries of neutrinos

Understanding neutrinos and how they oscillate, or change from one state to another, may be the key to understanding the universe.

Neutrinos are invisible particles, weighing almost nothing and constantly passing through our bodies by the trillions, traveling at nearly the speed of light. Scientists don’t know a lot about neutrinos, but they do know they come in at least three “flavors”—electron, muon and tau—and that they interact differently from each other when they encounter matter.

Underground experiments may help explain neutrino behavior

Mathew Muether, associate professor of physics, is one of several thousand scientists worldwide studying neutrino behavior. His grant support from the U.S. Department of Energy totals nearly $500,000 and finances his work on two projects anchored underground at FermiLab, the particle physics and accelerator laboratory in Batavia, Illinois.

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Muether began his work on the first project, NOνA (NuMI Off-axis ν_e Appearance), as a postdoc. NOνA scientists aim to understand the properties of neutrinos and their mass states in order to better understand the universe. As a postdoc, Muether helped design and build both of the NOνA neutrino detectors. NOνA’s near detector, which sits 350 feet below Fermilab, is exposed to an intense beam of billions and billions neutrinos which travel through the Earth to the far detector 500 miles away in Ash River, Minnesota.

“The near detector measures the neutrinos before they’re able to change and the far detector looks at the neutrinos after they’ve traveled and oscillated,” Muether said. “That lets us unravel some of the physics. People are developing theoretical models about how neutrinos can undergo this kind of transformation as they’re traveling.”

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Muether’s present role with NOνA is to facilitate long-baseline neutrino oscillation measurements. The work is funded by a two-year $275,000 DOE grant that also supports Fermilab’s DUNE (Deep Underground Neutrino Experiment) project. DUNE is in development and will start up when the NOνA experiment ends around 2030. The science behind NOνA and DUNE is similar, and once DUNE is operational, it will be able to do everything NOvA can do, only faster and better, Muether said. With the funding from this grant, Muether will also design and protoype a muon spectrometer for DUNE, and complete optimization studies and electronic prototyping work. He will design and demonstrate reconstruction and simulation software for the DUNE near detector, as well.

Muether’s second grant of $216,000 supports his work on DUNE exclusively. It is a sub-award of a DOE grant awarded to Heidi Shelman, chair and professor of physics, at Oregon State University. For this project, Muether is developing the computing and software infrastructure needed for the DUNE near detector.

“We expect this detector to produce data rates that are kind of unprecedented in the field. We don’t know what technologies can handle this amount of data that we’re expecting to output,” Muether said. “There are three unique parts of the DUNE near detector that are being designed. We need to connect them and make sure that they’re going to work together. One of my jobs is to make sure the software that’s getting developed to analyze the data will produce something cohesive.”

DUNE scientists will further study some of the outcomes and questions created by the NOνA experiments, specifically to determine the origin of matter and if neutrinos are why the universe is made of matter rather than anti-matter. DUNE scientists will also search for signals of proton decay, and look for black hole formation and the enormous streams of neutrinos released by dying stars. DUNE’s far detector site, being excavated now, will sit one mile below ground 800 miles away from Fermilab, at the Sanford Underground Research Facility in Lead, South Dakota.

Muether said both projects can contribute to science in ways more practical than understanding the origin of the universe. Particle physicists use the framework of the Standard Model, which is based on the firm theoretical understanding of the fundamental particles of nature.

“Understanding those fundamental particles has always led to really important practical advances for society like electronics and nuclear energy, and different potential sources and ways to produce energy,” Muether said. “Neutrinos are really interesting because they don’t fit into this standard theory. They are important in explaining nuclear fusion and fission processes. Trying to reconcile the properties of neutrinos and extend our theoretical understanding of how they operate with other particles may lead to some bigger understanding of how all these things work and lead to practical applications down the line.”

Student researchers gain valuable experience

Muether isn’t working alone on NOνA and DUNE at Wichita State. Several graduate students assist him with both projects.

Abdul-Wasit Yahaya, a master’s student in physics, is supporting machine learning techniques for the NOνA analysis. This project, he said, involves using deep learning to determine the point of interaction of outcoming particles in NOνA’s near detector. He describes the work as rewarding.

“The ability of a neutrino to change from one flavor to another as it travels between detectors or through space is something that greatly interests me because I often wonder what the depiction of such processes would look like,” Yahaya said. “Involving students in such significant and cutting-edge research is a means of fulfilling the dreams of young scientists like me who aspire to contribute to the understanding of the universe.”

Sushil Shivakoti, also a master’s student in physics, is assisting Muether with the muon spectrometer for DUNE. He said that because the properties of the neutrinos can't be studied directly, a good understanding of the muon's behavior in the spectrometer is crucial to the understanding of neutrinos' properties. He alters the shape, sizes and orientation of the steel plates of the subdetector and magnetic field within the muon spectrometer to see how it affects the behavior of muons.

“The exciting part of DUNE is that it can solve many underlying mysteries of the universe,” Shivakoti said. “It could explain the origin of matter, the unification of forces and black hole formation.

Three other young researchers are working alongside Muether on NOvA and DUNE. Palash Roy, a doctoral student in applied mathematics, is working on NOvA analysis and DUNE computing and detector design. Dustin Burgardt, a master’s student in physics, is working on DUNE magnet system design and prototyping. Michael Dolce, a postdoc who recently graduated from Tufts University, will work on NOνA and DUNE computing, analysis and detector design.

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