Fast-electron ejection from C, Ni, Ag and Au foils by 36 Ar 18 + (95 MeV/u): Measurements of absolute cross-sections
INFN and Dipartimento di Fisica e Astronomia, Via S. Sofia 64, I-95123, Catania, Italy
2 Centre Interdisciplinaire de Recherche Ions Lasers, (CEA/CNRS UMR 6637/ENSICAEN), CIRIL-Ganil, BP 5133, F-14070, Caen Cedex 05, France
3 DAPNIA/SPhN, CEA/Saclay, F-91191, Gif-sur-Yvette Cedex, France
4 INFN-LNS and Dipartimento di Fisica e Astronomia, Via S. Sofia 44, I-95123, Catania, Italy
* e-mail: email@example.com
Doubly differential electron velocity spectra induced by 36Ar18 + (95 MeV/u) from thin target foils (C, Ni, Ag, Au) were measured at GANIL (Caen, France) by means of the ARGOS multidetector and the time-of-flight technique. The main features observed in the forward spectra are convoy electrons, binary-encounter electrons, and (for the Au target only) a high-velocity tail which we attribute to a “Fermi shuttle” acceleration mechanism. Backward spectra do not show distinct structures. The spectra allow us to determine absolute singly differential cross-sections as a function of the target material and the emission angle. The convoy electron yield increases with the target atomic number, but for C their yield is so small that our experiment is not able to detect them. Absolute doubly differential cross-sections for binary-encounter electron ejection from C targets are well described by a transport theory which is based on the relativistic electron impact approximation (EIA) for electron production and which accounts for angular deflection, energy loss and energy straggling of the transmitted electrons.
© Società Italiana di Fisica and Springer-Verlag, 2004