OUR RESEARCH

Physicist Maria Anastasiou leverages LLNL’s accelerators to study nuclear reactions — from supernova explosions in stars, to reactions that are important to the Lab’s efforts in nuclear forensics and maintaining a safe, secure and effective stockpile. She earned a doctoral degree at Florida State University, with a research focus on experimental nuclear astrophysics, before joining LLNL as a postdoc in 2019. In 2022, she converted to a staff scientist position.

Maria values the flexibility she finds at LLNL, where she can shift her research focus to new areas, such as her transition from astrophysics research to developing alternative ways to measure nuclear reaction probabilities. She also enjoys using the Lab’s research tools to fine tune experimental techniques, including particle accelerators and detector configurations. For example, she uses instruments at the Lab’s Center for Accelerator Mass Spectrometry (CAMS) to irradiate target material and she leverages high-sensitivity AMS and gamma spectroscopy techniques to measure isotopes produced during the irradiation.

In addition, she’s eager to mentor future scientists, which motivated her to collaborate with four Lab scientists to launch a new internship program at LLNL where undergraduate students from a nearby university participate in hands-on nuclear science research at CAMS. The interns approach their research collaboratively, each taking on a different aspect of a project, such as preparing targets, conducting irradiation experiments, and analyzing nuclear reaction data. Maria’s perspective on the workplace culture at LLNL reflects this same theme — she values a highly collaborative environment, where she can interact with a variety of experts including chemists, materials scientists and data scientists.

Silvina “Silvi” Di Pietro received her Ph.D. in environmental chemistry from Florida International University in 2021. She joined the Class of 2021 National Nuclear Security Administration (NNSA) Graduate Fellowship Program as a postdoctoral scientist at Lawrence Livermore National Laboratory. Upon successfully completing her NNSA postdoctoral appointment, she transitioned to a research position at LLNL. Currently, she is working on both the Nuclear Materials Program’s Chemical Operations team as a certified fissile material handler and the Simulating Processing of Actinides and Developing Expertise (SPADE) project within the experimental team.

During her graduate studies, she was a Department of Energy (DOE) Fellow at the Applied Research Center (ARC). At the ARC, she assisted in the development of ammonia gas injection for uranium remediation at the DOE’s Hanford Site in Washington State. In 2022, Silvi was selected by the highly competitive CAS Future Leaders program sponsored by the American Chemical Society, the 2018 Innovators in Nuclear Technology R&D awarded by the DOE Office of Nuclear Energy and the 2016 Roy G Post Scholarship Foundation awarded by the Waste Management Symposia. She has been an International Union of Pure and Applied Chemistry (IUPAC)’s Division VI “Chemistry and the Environment” member since 2021.

When she’s not pushing the limits of chemistry, Silvi enjoys cycling, hiking, painting, traveling, watching soccer games and exploring art museums.

Nuclear engineer and analytical chemist Ruth Kips travels around the world working with allied nations to advance their nuclear forensic science and capabilities — and counter risks of nuclear smuggling. As the Lab’s associate program lead for nuclear smuggling detection and deterrence, Ruth delivers workshops on the importance of nuclear forensics and collaborates with partner countries on sample analysis.

The workshops are part of the U.S. National Nuclear Security Administration (NNSA)’s Global Material Security (GMS) program, aimed at preventing terrorists from acquiring nuclear or radiological material.

“Including nuclear forensics in the GMS portfolio enhances its detection capabilities at border crossings, seaports and airports,” Ruth says. “If nuclear material is found outside of regulatory control, the partner country can determine what the material is and where it came from. Forensics experts can determine what it is, its intended use and the threat level.”

With a master’s degree in nuclear engineering, a Ph.D. in analytical chemistry, several years conducting research in uranium-particle analysis, and a stint at the International Atomic Energy Agency (IAEA) as an inspector verifying that countries adhere to nuclear nonproliferation treaty commitments, Ruth holds a wealth of experience in each stage of the nuclear fuel cycle.

When he was growing up, Nicolas Schunck recalls always wanting to know ‘why’ things are the way they are. He says, “My desire to seek answers and bring a sense of order to the universe has inspired and fueled my scientific career as a theoretical nuclear physicist.”   

Nicolas’s research for the Nuclear and Chemical Sciences Division in the Physical and Life Sciences Directorate focuses on the fundamental mechanisms of nuclear fission and the development of theoretical methods to describe the structure and decay of heavy atomic nuclei. He has more than a decade of experience in high-performance computing applications on leadership-class computers and is active in the development and exploration of machine learning techniques to improve computational nuclear theory. For the last several years, Nicolas has served as principal investigator for the Fission in R-process Elements topical collaboration in nuclear theory, joining with five different institutions to better understand where and how heavy elements are formed in the universe. He has developed both a national and an international network of collaborations. Before joining Livermore as a staff scientist, he was a postdoctoral researcher at the University of Surrey (UK), Universidad Autonoma de Madrid and University of Tennessee.   

Nicolas holds a Ph.D. in theoretical nuclear physics, an M.S. in nuclear physics and a B.S. in physics from the University of Strasbourg (France). 

Quinn Shollenberger analyzes isotopes in meteorites and returned asteroid material to better understand our solar system. She also leverages her expertise in mass spectrometry to conduct mission-critical nuclear forensics research.

She started her journey at LLNL as an intern after earning her bachelor’s degree, diving into exciting cosmochemistry and nuclear forensics research projects. While pursuing a doctoral degree in cosmochemistry at the University of Münster in Germany, she returned to LLNL as a graduate intern. This experience led to a postdoctoral researcher role, and later a staff position at LLNL.

During her time as a postdoc, she received an internal funding award that enabled her to study a tiny sample from the Ryugu asteroid to learn about isotopic reservoirs in our early solar system. Quinn continues to develop and apply new analytical techniques, using sophisticated mass spectrometry instruments to measure a sample’s isotopic composition.

She enjoys working in a highly collaborative, multi-focus research environment, where she can explore big questions, like the formation of our solar system, while applying the same research methods to reduce the threat of smuggled nuclear materials.

For Quinn, the people she gets to work with are a big part of why she likes her job. She’s excited to collaborate with other LLNL cosmochemists and nuclear forensics experts, and she values connections with scientists from other institutions. On-site recreational activities, like lunchtime sand volleyball, also enrich her work environment.

Jingke Xu felt inspired to become a scientist at a young age because he enjoyed pondering problems that may or may not have answers. “As a scientist, every day brings something new — sometimes exciting and sometimes challenging,” he says. “I also try to apply scientific thinking to everyday life, both at the technological level and at the sociological level.” As a father, he enjoys explaining science to a young daughter, who asks, “Why?” dozens of times a day. 

While studying for his doctorate, Jingke worked on the detection of ghostly neutrinos from the Sun and the yet-to-be-discovered dark matter. Now, working as an experimental particle physicist in the Laboratory’s Nuclear and Chemical Sciences Division, Jingke develops new particle detection instruments and pushes existing technologies to their limits. He collaborates with scientists from universities and other national laboratories to hunt for rare particle interaction events. “LLNL provides a wonderful platform for me to pursue not only science but the applications of science,” he says.   

Jingke holds a Ph.D. in particle physics from Princeton University and a B.S. in physics from the University of Science and Technology of China.