Alumni Spotlight: Samuel Ajayi

Samuel Ajayi graduated from Florida State University in 2025 with a doctorate in physics from the Department of Physics, part of the College of Arts and Sciences. He currently works as an environmental specialist for the Bureau of Radiation Control at the Florida Department of Health where he helps regulate and oversee the responsible use of radioactive materials in hospitals, research labs, engineering companies and other settings.

Tell us about your background and what brought you to FSU.

I’m originally from Nigeria and earned my bachelor’s and master’s degrees in physics in 2012 and 2015, both from the University of Ibadan, Nigeria. I became fascinated by how physics and radiation can be applied to medicine like in radiotherapy, a cancer treatment that uses high doses of radiation to kill cancer cells. I applied to several doctoral programs but chose FSU for its strong research opportunities in my area. It’s been the perfect place to continue my journey as a researcher.

What inspired you to pursue physics?

My passion for physics began during childhood. I excelled in mathematics, physics and chemistry growing up but realized physics was what I loved. I was particularly drawn to research in nuclear physics because understanding the structure of the nucleus is essential for applications in diagnostic imaging such as X-rays, computerized tomography or CT scans, positron emission tomography or PET scans, and radiotherapy and radiation protection and safety. I was fascinated by how these tools allow us to see inside the body, and I wanted to understand the science that makes those applications possible.

Break down your research for us.

My research focuses on the nuclear structure of radioisotopes — unstable atoms that release radiation as they try to become stable. The nucleus is made of protons, which carry a positive charge, and neutrons, which carry no charge. When the balance between these particles is off, the atom becomes unstable. The way these particles are arranged gives each isotope a unique structure; studying that structure helps us predict behaviors like how the isotope decays, how long it remains radioactive, the type of radiation it emits, and how stable those emissions are before they are potentially used in medicine.

For my dissertation, I studied radioactive forms of elements such as Cobalt -59 to understand their excited states. We use gamma-ray spectroscopy to see inside the nucleus and uncover its structure without disturbing it. Detectors capture the gamma rays or radiation released by an unstable nucleus, and by analyzing their energy and pattern, I can rearrange the placement of protons and neutrons inside the nucleus. Before an isotope can be used in medicine or energy, we need to know its behaviors. My research ensures isotopes are applied safely and effectively in cancer treatment, radiotherapy and medical imaging.

Tell us about your current role at the Bureau of Radiation Control.

As an environmental specialist, I focus on radiation regulation and licensing. Many sectors like hospitals, airports, engineering companies, and research labs use radiation in their daily practices. My role is to review license applications from different institutions and evaluate their calculations, radiation protection designs, and the amount of radioactive material they plan to use to ensure their activities meet federal and state safety standards. Based on this review, we evaluate requests to make sure radiation is used responsibly.

Another important part of our work is security. We ensure the public remains protected from harmful exposure by sending inspectors into facilities and coordinating with law enforcement to detect and stop unauthorized radioactive material from entering public spaces, especially events with massive attendance. Our mission is to balance the essential benefits of radiation with strict safeguards that protect people and the environment.

What should the public know about your research?

There’s an assumption that studying nuclear physics means I work with nuclear bombs. I want the public to know that my research isn’t about weapons but about understanding nuclear structure to develop peaceful applications. Nuclear knowledge is critical for doctors to evaluate which isotopes are safe and effective for treatments like radiotherapy and diagnostic imaging. For example, the isotope Lutetium -177 emits beta particles that can treat cancer, while Strontium -90 is used for pain relief. Without this research, doctors wouldn’t know how to apply these isotopes safely. Nuclear physics is a field that can save lives.

How did your time at FSU prepare you for professional success?

The rigors of my doctoral program prepared me for the rigors of life. I learned to approach problems from multiple angles and developed a mindset of persistence and resilience — even when the answers aren’t clear, you don’t give up; you keep pushing until you find a solution. That experience taught me to keep searching for answers despite challenges.

What’s your best memory from your time at FSU?

My favorite memory was winning the Best Poster Award at the Gordon Research Conference in 2023 where I presented my dissertation research. This is a prestigious international conference with researchers from Japan, Europe and the U.S. Being honored and recognized on an international stage among so many talented scientists was truly unforgettable.

What faculty or staff members inspired you?

My adviser and associate professor of physics Vandana Tripathi has been an incredible role model and mentor. She played an important role throughout my time here by setting a high standard. I’m also grateful to the faculty at the John D. Fox Superconducting Linear Accelerator Laboratory. Their overall support and the feedback from my committee members constantly pushed me to aim higher, ultimately bringing out my best work.

Tell us about some upcoming projects.

I’m currently completing the analysis of an experiment I performed on nickel 62, a radioactive isotope used to study nuclear structure, at Argonne National Laboratory in Lemont, Illinois. Although I’m still finalizing the analysis, I look forward to publishing the research soon.

What advice do you have for current students?

Be persistent. Keep showing up because the moment you stop, it’s much harder to start again. When you finish, you’ll look back and be glad you didn’t quit.