Session RP1 - Poster Session VIII.
POSTER session, Thursday afternoon, October 30
Fran Hill Southeast Exhibit Hall, ACC
Knowledge of ion-atom ionization cross sections is of great importance for many accelerator applications. When experimental data and theoretical calculations are not available, approximate formulas are frequently used. Based on experimental data and theoretical predictions, a new fit for ionization cross sections by fully stripped ions is proposed. The Born approximation and classical trajectory calculations are frequently used to estimate the cross sections. Neither approximation is expected to be valid over the entire range of projectile ions and target atoms. Aspects of both models must be included in order to address the shortcomings in the underlying assumptions. A large difference in cross section, up to a factor of six, calculated in quantum mechanics and classical mechanics, has been obtained for 3.2GeV negative ions of iodine and positive ions of cesium. Because at such high velocities the Born approximation is well validated, the classical trajectory approach fails to correctly predict the stripping cross section at high energies for electron orbitals with low ionization potential.