Contribution Poster (A0 portrait)
An improved photo-nuclear cross section model for simulations of UHECR sources and extragalactic propagation
The transport of Ultra-High Energy Cosmic Rays (UHECR) through photon target fields requires a model for photo-nuclear interactions. The photo-meson energy regime around 150 MeV in nucleus rest frame is relevant for the production of pions off UHECR nuclei and successively for astrophysical and cosmogenic neutrinos. The models in present theoretical calculations, including codes like CRPropa, use a simple approach, which relies on the assumption that the photon interacts with a single quasi-free nucleon, while the rest of the nucleus remains intact. This model neglects nuclear effects such as the fragmentation of the remnant, the pion re-absorption and the broadening of s-channel resonances in nuclear matter or the photon-emission from de-excitation. Further, it has to assume some scaling relation of the total non-elastic photo-nuclear cross section with the nuclear mass. We present extensions to this so-called superposition model to address the mass scaling of the nonelastic cross sections and fragmentation of the remnant nucleus. The impact of these extensions is evaluated through simulations of UHECR accelerators and astrophysical neutrino production sites using the NeuCosmA framework.