The Inductive Impedance of the SPS

The hardware of the SPS has been modified considerably in recent years with the aim of reducing both the longitudinal and transverse impedance. The hardware change was followed up by a thorough measurement campaign [2,3,4,5]. We draw conclusions for the impedance based on these measurements. The results in the transverse plane depend critically on the difference between coherent and collective tune shifts especially important in the SPS. The longitudinal results may be surprising at first sight but can be explained by the different behaviour of dipole and quadrupole oscillation modes. All results are compared with the expected impedance derived from the harware at the time of measurement. The impedance at the horizon of 2006 is given as well, together with an updated value of the TMCI threshold.