Mines Physicists Contribute to New Results from MicroBooNE and Help Pave the Way for DUNE

South Dakota Mines assistant professor of physics, David A. Martinez Caicedo, Ph.D., and his research group are among the scientists who are part of the recent announcement from Fermi National Accelerator Laboratory on the MicroBooNE experiment's first results showing no hint of a sterile neutrino.

MicroBooNE is a large 170-ton liquid-argon neutrino experiment located on the booster neutrino beamline at Fermilab. The experiment is a critical part of the research needed to build and run the massive Deep Underground Neutrino Experiment (DUNE) now under construction at Sanford Underground research Facility (SURF) in Lead, SD.

The new results from the MicroBooNE experiment at the U.S. Department of Energy's Fermi National Accelerator Laboratory deals a blow to a theoretical particle known as the sterile neutrino. For more than two decades, this proposed fourth neutrino has remained a promising explanation for anomalies seen in earlier physics experiments. Finding such a particle would be a major discovery and a radical shift in our understanding of the universe.

However, four complementary analyses released by the international MicroBooNE collaboration and presented during a seminar all show the same thing: no sign of the sterile neutrino. Instead, the results align with the Standard Model of Particle Physics, scientists' best theory of how the universe works. The data is consistent with what the Standard Model predicts: three kinds of neutrinos—no more, no less.

Martinez says this research finding is significant for the neutrino physics community. “The results presented by MicroBooNE reduced the places where to look for hints of sterile neutrinos,” says Martinez.

During his post-doctoral work, Martinez helped build, install and test the system that reduces cosmic-ray background signals coming into the MicroBooNE detector. He also served a stint as the experiment coordinator who made sure the MicroBooNE detector remained operational, “Generally the collaboration rotated people each six months in this job because you are on call 24-7 and you're tasked to make sure everything works,” says Martinez. He and Ph.D. physics graduate student, Jairo Rodriguez, also built a remote MicroBooNE operations center on campus that allows graduate students and faculty to monitor and run the experiment remotely.

Understanding the MicroBooNE detector technology also helps inform planning for DUNE. Once operational, DUNE will be among the largest physics experiments on earth. Mines students and faculty are directly involved in many aspects of DUNE. “Being just an hour away from SURF and the future site of DUNE is a huge advantage for anyone studying at Mines,” says Martinez.

Martinez works alongside other physicists, including Rodriguez and Arturo Fiorentini, Ph.D., a former postdoctoral researcher at Mines. The team is working to build understanding of neutrino interactions inside the liquid argon time projection chambers used in both MicroBooNE and DUNE. Rodriguez is focusing on developing software tools that could enhance future searches of proton decay at DUNE. If proton decay occurs, researchers need to be able to differentiate it from the interactions between neutrinos and protons inside a liquid argon time projection chamber. “All of this work being done today in MicroBooNE has a direct translation to DUNE,” says Martinez.

Experiments like DUNE not only help solve some of the most fundamental questions of the universe, they also have huge potential for advancing future technology. “Many of the technologies developed in experiments like MicroBooNE and DUNE could be applied across multiple fields. One example of many is the photon detection devices that are a critical component of these experiments. We work on these detectors here at Mines, and they may also have important applications in medicine, to enhance the current technologies to diagnose diseases,” says Martinez.