Ionization of heavy ions in relativistic collisions with neutral atoms

The problem of ionization of ions in ion-ion and ion-neutral relativistic collisions is considered. Formulas for ionization cross sections are derived in the Born approximation in terms of the momentum transfer without allowance for magnetic interactions. Using these formulas implemented in the LOSS-R code, the ionization cross sections are calculated for the K shells of neutral atoms colliding with protons and also for 1$s$ and 2$p$ electrons of multiply charged heavy ions (nuclear charge $Z$ = 80–90) colliding with bare nuclei and neutral atoms. The calculation results are compared with experimental data and calculations of other authors.