Pion production in rare-isotope collisions

Pion energy spectra are presented for central collisions of neutron-rich $^{132}\mathrm{Sn}+^{124}\mathrm{Sn}$ and neutron-deficient $^{108}\mathrm{Sn}+^{112}\mathrm{Sn}$ systems using simulations with the Boltzmann-Uehling-Uhlenbeck transport model. These calculations, which incorporate isospin-dependent mean-field potentials for relevant baryons and mesons, display a sensitivity to the pion spectra that could allow significant constraints on the density dependence of the symmetry energy and its mean-field potential at suprasaturation densities. The predicted sensitivity increases with the isospin asymmetry of the total system and decreases with incident energy.