09/25/2025
By Amanda Vozzo
Date: Tuesday, Sept. 30, 2025
Time: 4 – 5 p.m.
Location: Olsen 503
Peter Bender, Assistant Professor, Department of Physics and Applied Physics, University of Massachusetts Lowell will give a talk on “Seeing the Invisible: High-Resolution γ-Ray Spectroscopy of Rare Isotopes.”
Abstract: The world around us is built from about 92 naturally occurring elements, each defined by its number of protons. For each element, changing the number of neutrons produces different isotopes: roughly 300 are stable, about 3,000 unstable isotopes have been observed, and theory predicts 7,000+ nuclides bound by the nuclear force. Near stability, many nuclei follow organizing “rules” captured by the nuclear shell model and its familiar magic numbers. Far from stability, those rules bend: new shapes appear, symmetries are tested, and unexpected structures emerge. Measuring the properties of these rare isotopes is essential. We do not yet have a single, comprehensive predictive model—different theoretical approaches succeed in different regions and for different observables—and many of the most exotic nuclides, found only in extreme astrophysical environments, appear to organize very differently than their stable counterparts.
In this talk, I’ll introduce how we produce and select rare isotopes and why a toolbox of reactions—β decay, transfer, and fusion–evaporation—paired with complementary detection methods provides a synergistic set of observables that constrain the nuclear interaction. I will present a few experiments across the nuclear chart to illustrate the distinct strengths of different laboratories and instruments and how combining their capabilities reveals where traditional rules bend and new patterns emerge.
Bio: Peter C. Bender is currently an Assistant Professor of Physics & Applied Physics at the University of Massachusetts Lowell. He earned a B.S. in Physics from North Georgia College & State University and an M.S./Ph.D. in Experimental Nuclear Physics from Florida State University. He has held key stewardship roles for the community’s flagship high-purity germanium (HPGe) arrays—TIGRESS at TRIUMF and GRETINA at NSCL/FRIB—together with their auxiliary detector systems. He currently serves in national leadership guiding U.S. efforts in high-resolution, in-beam γ-ray spectroscopy. His research specializes in high-resolution γ-ray spectroscopy and particle–γ coincidence techniques to study exotic nuclei. At UML he leads independently funded programs in both fundamental and applied nuclear science.