Speaker
Description
The electric-dipole (E1) strength plays a central role in understanding photoabsorption reactions, offering insights into nuclear structure, collective excitations, and the nuclear response to external fields. While E1 strength has been extensively investigated in heavy nuclei (A > 90)—where shell effects and nucleon correlations are less pronounced—the situation is more complex for lighter nuclei (A < 60). In these systems, clustering phenomena, isospin mixing, nuclear deformation, and neutron–proton pairing strongly influence charged-particle branching ratios. As a result, the common assumption that the neutron-emission channel (g,xn) adequately represents the total photoabsorption cross section breaks down. This complexity not only challenges theoretical interpretation but also leads to divergent model predictions. The issue has direct consequences for astrophysics, particularly the study of ultra-high-energy cosmic rays (UHECRs). Since their origin and production sites remain unresolved, improving our knowledge of UHECR energy-loss processes during extragalactic propagation is important.
The PANDORA project (Photo-Absorption of Nuclei and Decay Observation for Reactions in Astrophysics) is an international effort dedicated to systematically measuring photoabsorption cross sections, as well as proton, alpha, and gamma branching ratios, for light stable nuclei (A < 60). These results will provide essential constraints for nuclear models, which in turn will be implemented in UHECR propagation simulations. In this presentation, I will introduce the goals of the PANDORA project and discuss preliminary findings on 12-13C from its first experiment.