Doubly and triply differential ionization studies using positrons and electrons

Methods and results from experimental studies of single and multiple ionization of atoms induced by positron and electron impact are discussed. Coincidences between recoil ions, forward scattered projectiles and electrons ejected into a cone of angles are measured. From these data, doubly and triply differential cross-sections are extracted. Comparisons of the differential cross-sections and/or differential charge state fractions are being used to extract information about projectile charge effects on the collision dynamics as well as about the importance of various ionization mechanisms. Examples for ionization of argon and krypton atoms and nitrogen molecules are presented.