CHARGE ASYMMETRY IN THE DEPENDENCE OF STOPPING ON IMPACT PARAMETER

The charge asymmetry effects in the dependence of electronic energy loss on impact parameter are studied theoretically. Allowance for some corrections to the calculations made in terms of the first‐order perturbation theory is shown to result in a dependence of stopping on projectile charge sign. Corrections for binding‐energy variations and for Coulomb deflection are allowed for in the case of stopping on inner shells of atoms. A correction for electron cloud polarization is allowed for in the case of valence electrons. Particular calculations are carried out in case of proton and antiproton stopping by Si atoms. The antiproton energy loss proves to exceed the proton energy loss in case of low values of impact parameters, and vice versa in case of high values of impact parameters. As the projectile velocity increases, all the corrections decrease, thereby resulting in that the impact parameter dependences of the proton and antiproton stoppings become in practice identical. Copyright © 1990 WILEY‐VCH Verlag GmbH & Co. KGaA