Performance of the CERN ISR at 31.4 GeV

Due to the recent improvements in phase displacement acceleration, operating techniques and beam diagnostics, considerable progress has been achieved in operating the ISR at the maximum energy of 31.4 GeV (this centre of mass energy corresponds to a 2 TeV fixed target machine). High intensity stacks are stored at 26.6 GeV before acceleration by phase displacement to 31.4 GeV. At this energy up to 34 Amps are obtained with corresponding initial luminosities of 2.1031cm-2s-1 per intersection and 4.3 1031cm-2s-1 in a low-ß intersection. Due to the long beam lifetime, physics data taking may be performed over periods of 60 hours. The principle of phase displacement and the associated beam phenomena are discussed together with the control of the magnetic machine and the mutual interaction of the two beams. The operational technique is described and it is shown that the present day performance of the ISR at 31.4 GeV is comparable to the previous performance (1977) at 26.6 GeV. Consequently, in 1978 about 90% of the time requested for physics data collection was at 31.4 GeV.