Limited Energy Spread in an SSC

After having recalled the tolerances on the adjustments which mainly affect the energy spread out of an SSC either with or without RF flat-topping cavities, the special case of no flat-topping is considered with more detail. A method for cutting the bunches in phase in an SSC to a very short length while minimizing the loss is described. This length is then kept approximately constant in the isochronous cyclotrons themselves, since it is only affected by the radial acceleration gradient. In between, on the contrary, rebunchers are needed to counteract drift effects. The cases of curved paths and of the entrance or exit of a cyclotron, where the definition of an equivalent drift length requires special attention, is discussed. The importance at input and output of an SSC of having the particles transfered about their own energy dependent equilibrium orbit is emphasized.