A Young Eye on Ancient Stars: Contemporary experimental approaches to nuclear astrophysics measurements and extrapolations
Dr. Jakub Skowronski
University of Padua, Italy
The study of nuclear reactions that govern stellar evolution relies on precise measurements of cross sections at astrophysical energies. Direct approaches provide the most fundamental data, yet they are often hindered by extremely low reaction yields and numerous experimental subtleties that must be meticulously controlled. Overcoming these challenges depends on close collaboration between laboratories and the coordinated use of specialized facilities to probe reactions on key nuclei. To complement direct studies, indirect techniques play a crucial role. Among them, the Doppler Shift Attenuation Method (DSAM), combined with the state-of-the-art AGATA γ-ray tracking array, enables the measurement of nuclear state lifetimes with high precision. These lifetimes provide essential constraints on resonance properties, bridging gaps where direct data are scarce or inaccessible. Finally, connecting results from both direct and indirect methods requires robust extrapolations, which carry correlated uncertainties. Understanding and reducing these uncertainties is vital, as they propagate through nuclear reaction networks and influence astrophysical models. Together, these complementary strategies form an integrated framework to unravel the nuclear processes at the heart of the stars.
To illustrate these connections, examples of direct proton-capture reactions studies on CNO isotopes will be presented and different techniques discussed. As a complementary example, the measurement of lifetimes of excited states in 15O using the AGATA array will be shown and discussed, being one of the newest and cutting edge applications of the DSAM method. Finally, the impact of these experimental results on R-matrix extrapolations will be examined, with particular attention to strategies developed to quantify, reduce, and control the associated uncertainties.
Hosted by Dr. deBoer