Electron loss from fast heavy ions: Target-scaling dependence

Abstract

The target dependence for projectile electron loss is investigated using experimental data taken from the literature. Impact energies range from a few tens of eV/u to tens of MeV/u. For energies less than several MeV/u, the target dependences are shown to be very similar, independent of projectile species and charge state. Overall, however, with increasing impact energy the cross-section dependence on the target nuclear charge systematically increases. It is shown that none of the existing cross-section target scaling models reproduce these features. A model, based on Born scaling and including both the antiscreening and screening contributions to projectile electron loss, is developed. With the inclusion of relativistic effects, which increase the contribution from both channels at high energies, and "target saturation" effects, which reduce the contribution from the screening term for heavy targets and lower impact energies, this model describes quite reasonably all available experimental data. A simple scaling formula that reproduces the measured atomic number and impact velocity dependences is provided. This formula is applicable for projectile electron loss in collisions with either atomic or molecular targets and for impact energies ranging from a few to tens of MeV/u.

Strong asymmetry of the electron-loss-to-continuum cusp of multielectronU28+projectiles in near-relativistic collisions with gaseous targets

“…Experimental total cross sections for multielectron projectile ionization [23][24][25][26] have been partially reproduced by various theories [27][28][29]. A strong contribution of multiple ionization was observed in Refs.…”

Electron loss and capture from low-charge-state oxygen projectiles in methane

“…The formulas are considered to have predictive capabilities with accuracy within a factor of 2. The target dependence for projectile electron loss has also been investigated [17]. For energies less than several MeV/u, the target dependences were shown to be very similar, independent of projectile species and charge state [17].…”

Multiple ionization of neon induced by Li3+and C3+projectiles: influence of projectile screening in the ionization and electron capture channels

“…In the limiting case of completely dressed projectiles, the most comprehensive studies have been done in the environment of projectile electron loss where, viewed in the projectile reference frame, the neutral target plays the role of the 'projectile' in the process of projectile ionization [6][7][8][9][10][11][12][13]. Although many concepts developed for projectile electron loss apply and have been used to target ionization, these studies have been essentially restricted to projectile electron loss with one active electron and performed mainly for light targets (e.g.…”