Beam-Beam and Single Beam Effects in the SPS Proton-Antiproton Collider

The SPS is the first hadron collider operating with bunched beams and head-on collisions. In this respect, it is more similar to electron storage rings than to the ISR, but without the natural beam cooling due to synchrotron radiation damping. Therefore it was expected that the nonlinear beam-beam effect should play an important role in limiting the beam lifetime at a value of the beam-beam tune shift at least an order of magnitude below that achievable in electron machines. Experience has shown that this is, indeed, the case. With the design tune shift of 3 × 10-3 per intersection, dramatic effects are observed.