Cumulative ${\pi}$-Mesons in ${}^{{12}}{C}{+}{}^{{9}}$Be-Interactions at 3.2 GeV/Nucleon

In the FRAGM experiment at the heavy-ion accelerator$-$accumulator complex ITEP$-$TWA, yields of cumulative charged $\pi$ mesons have been measured in a fragmentation of carbon ions with the energy of 3.2 GeV/nucleon on a beryllium target. The momentum spectra of $\pi$ mesons cover four orders of the invariant cross section magnitude. They demonstrate the exponential fall with increasing energy. The measured inverse slope parameter is compared with similar measurements in nucleon–nucleus interactions and ion–ion collisions at lower energies. The energy dependence of the ratio of the yields of negative to positive $\pi$ mesons is presented. This dependence is discussed in a connection with Coulomb and isotopic effects. The obtained data are compared with predictions of several ion–ion interaction models.