Intrabeam scattering of lead ion LHC type bunches in the SPS

The classical theory of intrabeam scattering by A. Piwinski [1] has been successfully applied in the past to the Sp S [2] for dense proton and anti-proton bunches. The particle radius is an important ingredient in the scattering process. This parameter becomes very large for heavy ions compared with the radius of protons and intrabeam scattering rates may become troublesome even for modest bunch populations. The injection momentum of the LHC type lead ion bunches will be below transition in the SPS. Applying the theory and computing the growth rates may produce results that are not obvious at first sight. This paper tries to shed some light on the processes involved so that the computed growth rates are less cause for wonder. It does not propose any new element in the theory but only emphasizes a few aspects to clarify intrabeam scattering of relatively dense particle beams below transition.