Electron loss of fast projectiles in collisions with molecules

Abstract

The single-and multiple-electron loss of fast highly charged projectiles in collisions with neutral molecules is studied within the framework of a nonperturbative approach. The cross sections for single-, double-, and triple-electron losses are calculated for the collision system Fe q+ → N 2 (q = 24, 25, 26) at the collision energies 10, 100, and 1000 MeV/nucleon. The effects caused by the collision multiplicity and the orientation of the axis of the target molecule are treated. It is shown that the collision multiplicity effect leads to considerable differences for the cases of perpendicular and parallel orientations of the molecular axes with respect to the direction of the projectile motion, while for chaotic orientation such an effect is negligible.

New-type internal target for structural ion stripping

“…Strictly speaking, during the calculations of the ionization processes the total (not only as q 2 ) dependence of nonelastic form factors of the ion electrons on the acquired momentum should be taken into account and integrated over the impact parameters. Evidently, this alters the presented qualitative estimations, but the effect of target orientation on the ion ionization cross-section remains significant and can result [1,3] in an increase of several times in the projectile ionization cross-section. In this paper we will consider the equilibrium distribution of the charge content of the ion beam after the latter has passed through the target.…”

“…The effect of collision multiplicity -which contributes significantly to the cross-sections of non-elastic processes at the relative collision velocities that greatly exceed the characteristic atomic velocity -may relate to new and interesting effects that follow high-energy ion collisions. The effect was first predicted in theoretical studies by [1][2][3]; the most convincing arguments in pure physics that are used to study the effect of collision multiplicity are based upon a consideration of collisions with nanotubes oriented along the ion velocity. It should be stressed that there is still no experimental proof of the effect; such proof would be technically difficult and would require a heavy-ion accelerator.…”

“…If we select a material that can significantly increase the ionization cross-section at the unchanged recharge cross-section, this will result in significantly better stripping. How collision multiplicity can help to significantly improve the ion-beam stripping can be qualitatively explained [1][2][3]. The easiest way to illustrate the contribution of collision multiplicity is to consider the example of the collision of highly charged structured ions with a two-atom molecule (consisting of two identical atoms).…”

“…The effect was first predicted in theoretical studies in Refs. [1][2][3]; the most convincing arguments in pure physics that are used to study the effect of collision multiplicity are based upon a consideration of collisions with nanotubes oriented along the ion velocity. It should be stressed that there is still no experimental proof of the effect; such proof would be technically difficult and would require a heavy-ion accelerator.…”

“…Apart from expression (1) and its modifications other expressions are used, also obtained semi-empirically [9,10]. This paper shows that the charge composition of an ion beam can be significantly changed if targets showing the effect of collision multiplicity are used, since this effect increases [2,3] the ionization cross-sections due to multiple collisions. In fact, the equilibrium charge composition in the ion beam is determined by the ionization and recharge cross-sections [11,12].…”