Overlap knock-out effects in the CERN intersecting storage rings (ISR)

Overlap knock-out arises from an overlap between frequencies present in a bunched beam and the betatron frequencies in a stack. The 'single ring' effect in the interaction of a bunched beam with a stack in the same ring. Here the coupling forces are fairly linear and are transmitted by machine elements. The 'two-ring' effect is the interaction of a bunched beam with a stack in the other ring. Here the coupling forces are nonlinear since they are produced by the beam-beam interaction. A brief outline of the general theory of these effects is given. The single ring and two-ring dipole effects have been observed and shown to cause a large increase in the transverse size of the stacked beam. (4 refs).