Wei Jia Ong, a staff scientist at Lawrence Livermore National Laboratory (LLNL), has been recognized as the recipient of the American Physical Society's (APS) 2025 Stuart Jay Freedman Award in Experimental Nuclear Physics.
The award is presented annually to an outstanding early career experimentalist in nuclear physics. Ong was selected for her work "spearheading a multifaceted effort that uses radioactive beams to better understand Type-I X-ray bursts and other astrophysical phenomena through studies of beta decay, nuclear reactions and nuclear masses."
"It is an unbelievable honor to win this award," said Ong. "At the same time, science is not done in a vacuum. I have been extremely fortunate throughout my research career to have had amazing mentors and peers."
Ong's research focuses on nuclear astrophysics, particularly the formation of elements in the cosmos and the nuclear reactions that take place in neutron stars.
The award recognizes Ong's study of X-ray bursts, in which a neutron star siphons and heats material from a companion star. Eventually, the accreted gas becomes hot enough to trigger a thermonuclear explosion on the surface of the neutron star.
"Imagine the mass of a mountain being squashed into a teaspoon. That's how dense neutron stars are," she said. "X-ray bursts act as perturbations on the neutron star. How the neutron star acts when it undergoes X-ray bursts and how it cools after the explosions are over tell us what the interior of the neutron star looks like."
Ong and her collaborators have taken measurements to precisely determine the mass and nuclear structure of elements produced in X-ray bursts.
"These quantities enable us to calculate the rates for nuclear reactions occurring during the X-ray burst," she said.
Looking ahead, Ong hopes to investigate how proton-rich stable nuclei are made in stars.
"This is one of the unsolved mysteries in the approximately 70-year history of nuclear astrophysics, and I think there are a lot of interesting avenues to explore," she said.
Ong joined LLNL as a Lawrence Fellow - a highly competitive postdoctoral position offered at the Laboratory. She is now a staff scientist in the Nuclear and Chemical Sciences Division.
"There is a lot of overlap between nuclear astrophysics, and, for example, the high energy density science done at LLNL," she said. "There is a lot to be learnt from fundamental nuclear science efforts."
Ong earned a Ph.D. in physics from Michigan State University and a B.A. in physics from Washington University in St. Louis. She performs experiments at accelerator-based radioactive isotope production facilities such as the Facility for Rare Isotope Beams at Michigan State University and the Argonne Tandem Linac Accelerator System at Argonne National Laboratory.
The APS award was established in 2016 in honor of Stuart J. Freedman, a distinguished experimental nuclear physicist with a devotion to educating and mentoring graduate students and postdoctoral researchers. As the recipient, Ong will receive $5,000, a certificate, a registration waiver and an allowance for travel to the fall meeting of the APS Division of Nuclear Physics to give an invited prize talk and receive the award.
