Congratulations to physics graduate students Caroline Riggall and Aidan Gardner-O’Kearny on their poster prizes at the 2026 Meeting of the American Physical Society Division of Particles and Fields. Held at Fermilab, the meeting brought together like-minded researchers to share their work, review the status of the field, and consider future directions.

Riggall and Gardner-O’Kearny are part of the department’s collider physics group and work with Associate Professors Larry Lee and Tova Holmes. They’re contributing to research for a possible muon collider, a next-generation tool for exploring energies beyond current capabilities in the search for new physics. Particle colliders typically rely on beams of protons and electrons. Muons are much heavier than electrons and, unlike protons, have no smaller components to siphon off energy in a collision. A muon collider would have greater energy yet come with a smaller footprint and offer more efficiency than existing facilities.

Riggall is stationed at Fermilab and won for her work titled “Solenoid-Based Lattices for Muon Ionization Cooling.” She addressed a principal challenge for a muon collider: cooling the beam so particles stay in a tight configuration and reach target luminosity. Current methods can’t keep up with how quickly muons decay (in about two microseconds). Riggall’s solution proposes ionization cooling by passing the beam through an absorbing channel—in this case solenoid-based focus-focus (FOFO) lattices with alternating polarity—that would cool both negative and positive charges in a single channel.

Gardner-O’Kearny worked at Fermilab over the summer and is back on campus this fall to pursue his doctoral work. His winning poster was “Electromagnetic Shower Reconstruction with the MAIA Detector.” Within the muon collider framework, the MAIA (Muon Accelerator Instrumented Apparatus) is a proposed detector with several layers, each designed to reconstruct different properties of particles.Muons from the incoming beam will decay into high-energy electrons and neutrinos, with the electrons generating electromagnetic showers as they interact with beamline components. Gardner-O’Kearny focuses on identifying the electrons resulting from collisions and differentiating them from beam-induced backgrounds.

A muon collider is a key aspect of the country’s particle physics roadmap and part of three central themes for the particle physics future: decipher the quantum realm, illuminate the invisible universe, and explore new paradigms in physics. UT’s high energy/particle physics group, including undergraduate and graduate students, is helping lead the way.