Nuclear fragmentation and charge-exchange reactions induced by pions in the $\Delta$-resonance region

TL;DR

This study investigates how pions near the Δ(1232) resonance influence nuclear fragmentation and charge-exchange reactions using the Lanzhou quantum molecular dynamics model, revealing the dominant role of Δ resonance formation and weak energy dependence of fragmentation.

Contribution

It introduces an isospin, momentum, and density-dependent pion-nucleon potential into the LQMD model to analyze pion-induced nuclear reactions near the Δ resonance.

Findings

Absorption to form Δ resonance dominates target heating.

Fragmentation magnitude weakly depends on pion energy.

Isospin ratio in charge exchange affected by target nucleus isospin.

Abstract

Dynamics of the nuclear fragmentations and the charge exchange reactions in pion-nucleus collisions near the $\Delta$(1232) resonance energies has been investigated within the Lanzhou quantum molecular dynamics (LQMD) transport model. An isospin, momentum and density-dependent pion-nucleon potential is implemented in the model, which influences the pion dynamics, in particular the kinetic energy spectra, but weakly impacts the fragmentation mechanism. The absorption process in pion-nucleon collisions to form the $\Delta$(1232) resonance dominates the heating mechanism of target nucleus. The excitation energy transferred to the target nucleus increases with the pion kinetic energy and is similar for both $\pi^{-}$ and $\pi^{+}$ induced reactions. The magnitude of fragmentation of target nucleus weakly depends on the pion energy. The isospin ratio in the pion double charge exchange is influenced by the isospin ingredient of target nucleus.