°-Electron Emission In Fast Heavy Ion Atom Collisions

Biological damages such as mutations, chromosomal aberrations etc. are consequence of biochemical changes mostly in the DNA /1/. With ionizing radiation, these chemical changes are due to primary ionization events and secondary ionization effects caused by the primarily produced electrons. Differences in the biological response of densely ionizing radiation, like heavy charged particles, in comparison to sparsely ionizing radiation, such as X- or γ-rays, are mainly due to the differences in the productions of the so called δ-electrons. Therefore, the emission process of electrons i.e., the cross section for the primary ionization event as well as the energy and angular distribution of the emitted electrons should be understood in detail. The δ-electron emission processes occurring in fast heavy ion atom collisions are explained qualitatively. The different spectral structures of electron emission arising from either the target or the projectile are explained in terms of simple models of the kinetics of momentum transfer induced by the COULOMB forces. In collisions of very heavy ions with matter, high nuclear COULOMB forces are created. These forces lead to a strong polarization of the electronic states of the participated electrons. The effects of this polarization are discussed. © 1991.