Barkas effect, shell correction, screening and correlation in collisional energy-loss straggling of an ion beam
Physics Department, University of Southern Denmark, 5230 Odense M, Denmark
2 Institut für Experimentalphysik, Johannes-Kepler-Universität, 4040 Linz-Auhof, Austria
Revised: 1 December 2002
Published online: 4 February 2003
Collisional electronic energy-loss straggling has been treated theoretically on the basis of the binary theory of electronic stopping. In view of the absence of a Bloch correction in straggling the range of validity of the theory includes both the classical and the Born regime. The theory incorporates Barkas effect and projectile screening. Shell correction and electron bunching are added on. In the absence of shell corrections the Barkas effect has a dominating influence on straggling, but much of this is wiped out when the shell correction is included. Weak projectile screening tends to noticeably reduce collisional straggling. Sizable bunching effects are found in particular for heavy ions. Comparisons are made with selected results of the experimental and theoretical literature.
PACS: 34.50.Bw – Energy loss and stopping power / 52.40.Mj – Particle beam interactions in plasmas
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2003