From Giants and Pygmies – Atomic Nuclei in the Photon Bath

All matter in our universe was and is constantly bombarded by photons spanning a range of energies, from the lowest to the highest. Photons with high energies can lead to photoexcitation and photodisintegration of atomic nuclei. Today, the majority of photons originate from heated objects, emitting a Planck photon bath with a continuous energy distribution.

Typically, only photons within the energy regime of hundreds of keV to MeV can induce nuclear reactions. These photons are, for example, responsible for the elemental abundance peak in the iron and play a major role in the r and p processes of nucleosynthesis in explosive stellar environments. Photons in the MeV range are very penetrating. This characteristic is crucial for various applications. Examples include irradiation of cells in tumor therapy, the screening of cargo containers for homeland security measures, or the identification of contraband.

Understanding how atomic nuclei near and far from the valley of stability interact with photons requires a combination of very different experimental approaches. In my talk, I will try to build a bridge between historical experiments and recent developments in the field.