ORNL’s Jason Newby advances neutrino research frontiers

Scientist Jason Newby measures phenomena that have never been observed, including a neutrino bouncing off an atomic nucleus - a signal as subtle as the tiny recoil of a bowling ball struck by a ping-pong ball. Capturing that effect is the kind of precision physics at the heart of a world-class research program Newby helped build at the Department of Energy's Oak Ridge National Laboratory.

As leader of the Nuclear and Particle Physics Section in ORNL's Physics Division, Newby studies the fundamental properties of neutrinos, electrically neutral subatomic particles that pass through matter almost like ghosts and are notoriously difficult to detect. He is also a founding member and deputy spokesperson of the COHERENT collaboration at ORNL's Spallation Neutron Source (SNS), which uses the world's brightest accelerator-produced neutrino pulses to conduct experiments at the limits of detection.

Working with ORNL staff, collaborators and students, Newby helps generate measurements essential to advancing theories about neutrinos. He also partners with researchers in the nuclear nonproliferation community to explore applications of neutrino instrumentation for nuclear security.

"Neutrinos can provide insights about other fundamental particles, the structure of the universe and key phenomena in astrophysics, particle physics and cosmology," Newby said. "Much remains to be discovered about their nature."

Fundamental questions persist. Scientists still do not know the full picture of how neutrinos interact with matter, how much they weigh or whether the neutrino is its own antiparticle. If it is, that discovery could help explain why the universe contains more matter than antimatter.

About a decade ago, through engagement with the international physics community, Newby helped establish ORNL's neutrino research program. From the start, his goal was to push the boundaries of basic science while testing and refining the Standard Model of particle physics, the framework that describes fundamental particles and their interactions.

That effort centered on the unique capabilities of SNS and the High Flux Isotope Reactor (HFIR), which are both DOE Office of Science user facilities at ORNL. Because neutrinos are a byproduct of neutron production, SNS and HFIR offer exceptional opportunities to study how neutrinos interact with matter.

One result was COHERENT, an international collaboration of 80 researchers from 19 institutions in four nations. In 2017, the experiment became the first to detect and characterize coherent elastic neutrino-nucleus scattering (CEνNS, pronounced "sevens"), an interaction theorist had predicted 43 years earlier: neutrinos collectively scattering off a nucleus and imparting a minute amount of energy. The discovery was made at SNS using the world's smallest neutrino detector, installed in a service corridor known as Neutrino Alley.

"After we made that measurement in 2017, we saw an international community form, blossom and create an entire subfield of particle physics with new ways of asking questions and designing experiments," Newby said. "Theorists who could spend their time calculating anything suddenly started picking up a set of problems that had been abandoned for more than 30 years."

To date, SNS remains the only accelerator laboratory where CEνNS has been measured - although ORNL physicists have now detected it using three separate experimental setups. Newby said these and other measurements he and his colleagues continue to prepare at Neutrino Alley will help scientists interpret results from other major neutrino experiments, including the Super-Kamiokande observatory in Japan and the Deep Underground Neutrino Experiment (DUNE) in the United States.

"Every year we get together for a workshop, we realize how that one measurement and the precision measurements that are now building on it have broadly impacted the particle physics community," Newby said. "I couldn't have predicted this - it's just incredible."

Today, ORNL is an international leader in materials and detectors for extreme environments, and DOE's former High Energy Physics program recently labeled ORNL as "a national landmark for neutrino science." Over the last five years, Newby has onboarded more than 35 students, postdoctoral fellows and faculty members to pursue neutrino projects. He sees that pipeline as one of the program's distinctive strengths.

"We've created a space where people interested in neutrino physics can think of an idea as a grad student, make a measurement and collect and analyze the data before graduation," Newby said. "That is being able to do neutrino science on a timescale meaningful to an early-career scientist, which is unique in particle physics."

Newby's group also participated in the Precision Oscillation and Reactor Spectrum Experiment, or PROSPECT, which operated at HFIR until achieving its initial goal. PROSPECT studied antineutrinos produced by nuclear reactors, examining neutrino oscillations, measuring the antineutrino energy spectrum and investigating reactor neutrino anomalies.

Now Newby is helping guide the neutrino program's next phase. He said SNS and HFIR together will enable researchers to probe ways neutrinos may reveal physics beyond the Standard Model.

For Newby, the work is also personal. Raised in McMinnville, Tennessee, he was encouraged by a high school science teacher to pursue higher education in the state. He went on to attend King College in Bristol and the University of Tennessee, Knoxville, and he remains committed to creating opportunities for students who aspire to careers in science.

"A large portion of students from the surrounding area come to the lab and get to perform cutting-edge research," Newby said. "I'm glad that ORNL stays engaged with the small schools and liberal arts colleges to give students and early-career folks the opportunity to become scientists. Even scientists with small-town roots can have global impact."

UT-Battelle manages ORNL for DOE's Office of Science, the single largest supporter of basic research in the physical sciences in the United States. The Office of Science is working to address some of the most pressing challenges of our time. For more information, please visit energy.gov/science. - Scott Gibson