IONIZATION OF ATOMS BY PARTICLE AND ANTIPARTICLE IMPACT

In this report we review, and put in context, the recent experimental and theoretical developments generated by the use of particle and antiparticle beams in exploring the effects of changing the sip of the perturbing potential in atomic collisions. We firstly give a brief outline of the history of antiparticles and follow this with a discussion of modern experimental techniques with an emphasis on the LEAR antiproton beam. We next review experiments on the measurement of single ionization cross sections. In a brief introduction to the theory of scattering from a one-electron atom we outline the theoretical ideas that lie behind the concepts of increased binding and polarization. Both analytical approaches to the problem, such as the Glauber method, and numerical approaches such as variational expansions in a finite Hilbert basis set (FHBS) are discussed. We show bow measurements of two-electron processes give a measure of the role correlation plays in an ion-atom collision and we review the theoretical response to the new generation of experiments on many-electron atoms. Finally we see how much we have learned that is applicable to the stopping powers of charged particles in solids.