Seminarium Fizyki Jądra Atomowego

Prompt and delayed gamma ray spectroscopy of nuclear reactions inducing fission can reveal a wealth of important information. Study of gamma emission before fission occurs can probe rare phenomena such as the population and back-decay of the fission shape isomers – metastable states with very large deformations which sit on the pathway to fission [1][2]. Conversely, gamma spectroscopy of the de-exciting fragments after fission occurs not only allows study of the nuclear structure of neutron-rich nuclei, but also provides essential information on the fission process itself [3]. This presentation will give an overview of spectroscopy of the fission shape isomers in actinide nuclei and show recent results concerning their gamma back decay. New results from the nu-Ball2 campaign at the ALTO facility in Orsay will also be presented on the emission of high energy gamma rays from fission fragments. The measurement of fission fragment gamma ray angular distributions will also be discussed, since these are related to the relative orientations of fragment spins, a topic on which there is currently strong disagreement between different theoretical approaches [4][5][6]. Perspectives on future experiments will be highlighted.

References:
[1] C. Hiver, J.N. Wilson et al., Acta Physica Polonica, Proceedings of the Zakopane Conference on Nuclear Physics, Vol. 18 (2025)
[2] S. Leoni, B. Fornal, N. Mărginean and J.N. Wilson, Eur. Phys. J. Spec. Top. 233, 1061–1074 (2024)
[3] J.N. Wilson et al., Nature 590, p566–570 (2021)
[4] J. Randrup, Phys. Rev. C 106, L051601 (2022)
[5] A. Bulgac et al., Phys. Rev. Lett. 128, 022501 (2022)
[6] G. Scamps et al., Phys. Rev. C 108, L061602 (2023)