Research

The focus of my research is the structure of atomic nuclei in the regime of very unbalanced proton and neutron numbers. Short-lived radioactive nuclei that contain many more neutrons than protons often reveal surprising properties: Their shape and excitation pattern as well as the energy and occupation of their quantum mechanical orbits by protons and neutrons is significantly altered as compared to stable nuclei. My group uses nuclear reactions to probe such changes in the nuclear structure. Since our nuclei of interest are short-lived and cannot be made into targets, the beam is made up of them. We have at hand an arsenal of different reactions to probe specific nuclear properties. These include scattering as well as reactions that remove or add a nucleon. The experimental challenge is then two-fold: We must identify all reaction residues (particle spectroscopy) and identify the final state they were left in (gamma-ray spectroscopy). Our results are then confronted with theoretical modeling on the quest to unravel the driving forces of structural change in the regime of short-lived nuclei. This is critical to understand the nature of the nuclear force and to ultimately arrive at a predictive model of atomic nuclei that also holds for the shortest-lived ones which cannot be produced on Earth but whose properties are central to modeling the reactions and decays responsible for the elemental and isotopic fingerprints of visible matter in the Universe.

Biography

I grew up in Germany being very fond of chemistry, mathematics, and physics and ended up studying physics at the Universität zu Köln where I got my PhD-equivalent with experimental nuclear science research at the local tandem accelerator laboratory. I enjoyed coming up with stable target-projectile combinations that produced my nucleus of interest at the desired excitation energy and angular momentum either directly in a nuclear reaction or subsequently in a nuclear decay. My group’s work today builds on this, only that FRIB allows us to probe the most exotic and interesting nuclei possible as we can use rare-isotope beams to induce nuclear reactions. We use gamma-ray spectroscopy to characterize the excited states of the short-lived reaction products, and the resulting spectra provide fantastic fingerprints of the quantum mechanical inner workings of nuclei that we can only study at FRIB.

How students can contribute as part of my research team

The results from our experiments are often surprising and reveal exciting changes in the structure of exotic nuclei as compared to stable species. We collaborate closely with nuclear structure and reaction theorists. Our experimental input helps to unravel the driving forces behind the often spectacular modifications in nuclear structure and adds to the improvement of nuclear models that are aimed to compute nuclear properties with predictive power also in the exotic regime. Projects in my group involve the analysis of new and exciting data, large-scale detector simulations, hands-on detector upgrades, or a combination of the above.

Scientific publications

• In-beam spectroscopy reveals competing nuclear shapes in the rare isotope ⁶²Cr, A. Gade et al., Nat. Phys. 21, 37 (2025).
• Probing proton cross-shell excitations through the two-neutron removal from ³⁸Ca, T. Beck et al., Phys. Rev. C 108, L061301 (2023).
• Dissipative Reactions with Intermediate-Energy Beams: A Novel Approach to Populate Complex-Structure States in Rare Isotopes, A. Gade et al., Phys. Rev. Lett. 129, 242501 (2022).
• Exploring the role of high-j configurations in collective observables through the Coulomb excitation of ¹⁰⁶Cd, D. Rhodes et al., Phys. Rev. C 103, L051301 (2021).
• Shape Changes in the N=28 Island of Inversion: Collective Structures Built on Configuration-Coexisting States in ⁴³S, B. Longfellow et al., Phys. Rev. Lett. 125, 232501 (2020).