15/11: Seminario: Fermi-shuttle type multiple electron scattering in atomic collisions

Seminario en Aula IAFE
Jueves 15 Nov 16hs

Fermi-shuttle type multiple electron scattering in atomic collisions

Dr. Károly Tõkési

Institute of Nuclear Research of the Hungarian Academy of Sciences
(ATOMKI) Debrecen, Hungary

Double differential spectra of electrons ejected in ion-atom or ion-solid
collisions are in the focus of general interest for a long time. These
spectra are relatively easy to measure, and they show many fine details
relevant for the collisions dynamics. In the past decade special effort
has been devoted to understand the high energy part of the electron
spectra. Significantly enhanced emission of fast electrons far above the
so-called binary encounter energy was observed in both ion-atom and
ion-solid collisions. In some cases, fast electrons have been identified
from double, triple and quadruple scattering by the projectile and target
cores. The ejected electron gains energy in every encounter with the
projectile in such processes. This mechanism is often referred to as
Fermi-shuttle acceleration.

We show that this process can produce a significant enhancement in the
emission yield of high energy electrons. After a brief history of the
study of Fermi-shuttle acceleration mechanisms in atomic collisions, we
present results of our recent systematic experimental studies and the way
of identifying and analyzing the multiple scattering components by the
help of classical trajectory Monte Carlo calculations.