Physicists have charted a course for the next decade of worldwide research focusing on neutrinos, which are incredibly small particles that can pass through nearly everything by the trillions every second at nearly the speed of light.
The goal of physicists is to uncover fundamental insights about the universe’s origins by studying these minute particles.
Professor Alexandre Sousa from the University of Cincinnati played a significant role in outlining this new phase of research into neutrino behavior. These particles are generated through processes such as nuclear fusion in the sun, radioactive decay in various environments like nuclear reactors and the Earth’s crust, or in particle accelerator facilities. As they travel, neutrinos can change between three distinct types or “flavors.”
However, surprising experimental findings have led scientists to speculate the existence of a fourth type known as a sterile neutrino, which seemingly does not interact with three of the four known forces in nature.
“While it theoretically interacts with gravity, it does not engage with the weak nuclear force, strong nuclear force, or electromagnetic force,” Sousa explained.
In a recent white paper published in the Journal of Physics G, Sousa along with his co-authors dive into experimental inconsistencies in neutrino studies that have puzzled experts.
The collective vision presented in the paper aligns with science funding proposals from the Particle Physics Project Prioritization Panel, often referred to as P5. Their final report released in 2023 made specific funding recommendations to Congress for these research projects.
“Neutrino physics is making strides in multiple areas,” stated co-author and UC Professor Jure Zupan.
In addition to the hunt for sterile neutrinos, Zupan noted that physicists are investigating various experimental inconsistencies—discrepancies between theoretical predictions and actual data—that can be explored in upcoming experiments.
One intriguing question is why there is significantly more matter than antimatter in the universe, even though the Big Bang is thought to have produced them in equal amounts. Sousa believes neutrino research could shed light on this mystery.
“Even if it doesn’t impact your daily life, we’re attempting to grasp the reasons for our existence,” Sousa commented. “Neutrinos seem to be crucial in unlocking these profound questions.”
Sousa is involved in a highly ambitious neutrino project known as the Deep Underground Neutrino Experiment (DUNE), which is organized by the Fermi National Accelerator Laboratory. Teams are working on excavating the former Homestake gold mine located 5,000 feet underground to set up neutrino detectors. Sousa shared that it takes approximately 10 minutes for the elevator to reach the cavern where the detectors are housed.
The placement of detectors underground helps shield them from cosmic rays and background radiation, allowing for a clearer observation of the particles produced during experiments.
“With these two detector modules and the most powerful neutrino beam ever created, we can accomplish a substantial amount of science,” Sousa noted. “The activation of DUNE will be incredibly thrilling. It promises to be the leading neutrino experiment to date.”
This paper is a remarkable collaboration effort, involving over 170 contributors from 118 different universities or institutions, along with 14 editors including Sousa.
“This project exemplifies collaboration among a diverse group of scientists. It can be challenging at times, but it’s gratifying when everything falls into place,” he remarked.
In the meantime, Sousa and UC Associate Professor Adam Aurisano are also participating in another Fermilab neutrino project called NOvA, which investigates how and why neutrinos alter their flavors. In June, their research group published findings that represent the most accurate measurements of neutrino mass to date.
Additionally, a significant project named Hyper-Kamiokande (Hyper-K) is currently being developed in Japan, set to be a neutrino observatory and experiment.
“Combining results from Hyper-K and DUNE should yield fascinating insights. Together, these two experiments will greatly enhance our understanding,” Sousa predicted. “We anticipate having some answers by the 2030s.”
