Charge-Exchange Reactions Accompanied by a Single ${\pi }^{+}$ Production in Medium-Energy Heavy-Ion Collisions

Abstract

Heavy-ion charge-exchange (CE) reactions provide a sensitive probe of isospin dynamics in nuclear collisions. We investigate the reaction ${}^{12}\mathrm{C}{(}^{12}\mathrm{C},{}^{12}\mathrm{N}{\pi }^{+}){}^{12}\mathrm{Be}$ at 400--600 A MeV within the ultra-relativistic quantum molecular dynamics model combined with a phase-space coalescence approach. This reaction represents a nontrivial CE channel accompanied by a single ${\pi }^{+}$ production in heavy-ion collisions, extending previous studies from lepton-induced to hadronic systems. The ${}^{12}\mathrm{N}$ fragment is formed via nucleon and meson exchange, whereas ${\pi }^{+}$ production is primarily governed by $\Delta$ resonance excitation and decay, enabling simultaneous investigations of CE processes and $\Delta$-induced pion production within the same reaction system. We calculate the reaction cross section and analyze the four-momentum distributions of ${}^{12}\mathrm{N}$ and ${\pi }^{+}$. Characteristic phase-space features reflect different production mechanisms and provide guidance for future experimental designs. Additionally, this reaction may serve as a potential pathway for rare-isotope production.

Comments: 26 pages, 21 figures. To be published in Chinese Physics C