The interactions between a beam of charged particles and the residual gas will be described. In principle we should cover beams consisting of any type of charged particles. Clearly, this is an impossible task, but most types are included. Also, only the most important interactions are described. The interactions between the beam and the residual gas will lead to a reduction in the lifetime, and possibly an increase of the beam emittance. Knowing the cross section for the interaction in question, these effects can be calculated. Finally, the effects these interactions will have on the surroundings in terms of radiation and background will be mentioned briefly. 1
