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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鈥檛 know a lot about neutrinos, but they do know they come in at least three 鈥渇lavors鈥濃�攅lectron, muon and tau鈥攁nd 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, NO谓A (NuMI Off-axis 谓_e Appearance), as a postdoc. NO谓A 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 NO谓A neutrino detectors. NO谓A鈥檚 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.

鈥淭he near detector measures the neutrinos before they鈥檙e able to change and the far detector looks at the neutrinos after they鈥檝e traveled and oscillated,鈥� Muether said. 鈥淭hat lets us unravel some of the physics. People are developing theoretical models about how neutrinos can undergo this kind of transformation as they鈥檙e traveling.鈥�

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Muether鈥檚 present role with NO谓A is to facilitate long-baseline neutrino oscillation measurements. The work is funded by a two-year $275,000 DOE grant that also supports Fermilab鈥檚 DUNE (Deep Underground Neutrino Experiment) project. DUNE is in development and will start up when the NO谓A experiment ends around 2030. The science behind NO谓A 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鈥檚 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.

鈥淲e expect this detector to produce data rates that are kind of unprecedented in the field. We don鈥檛 know what technologies can handle this amount of data that we鈥檙e expecting to output,鈥� Muether said. 鈥淭here are three unique parts of the DUNE near detector that are being designed. We need to connect them and make sure that they鈥檙e going to work together. One of my jobs is to make sure the software that鈥檚 getting developed to analyze the data will produce something cohesive.鈥�

DUNE scientists will further study some of the outcomes and questions created by the NO谓A 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鈥檚 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.

鈥淯nderstanding 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,鈥� Muether said. 鈥淣eutrinos are really interesting because they don鈥檛 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.鈥�

Student researchers gain valuable experience

Muether isn鈥檛 working alone on NO谓A and DUNE at Wichita State. Several graduate students assist him with both projects.

Abdul-Wasit Yahaya, a master鈥檚 student in physics, is supporting machine learning techniques for the NO谓A analysis. This project, he said, involves using deep learning to determine the point of interaction of outcoming particles in NO谓A鈥檚 near detector. He describes the work as rewarding.

鈥淭he 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,鈥� Yahaya said. 鈥�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.鈥�

Sushil Shivakoti, also a master鈥檚 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.

鈥淭he exciting part of DUNE is that it can solve many underlying mysteries of the universe,鈥� Shivakoti said. 鈥淚t 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鈥檚 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 NO谓A and DUNE computing, analysis and detector design.

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