Part. Accel. Part. Accel. PS-XXI, a new synchrotron for the LHC injector Autin Bruno Cappi R Garoby R Gruber J Riunaud J P Schindl Karlheinz 1997 58 103 119 The CERN PS is the oldest link in the LHC injector chain. A separate function substitute synchrotron is discussed. It would keep the versatility of the present machine and have a higher extraction energy to relax the tolerance on the microwave instability threshold at injection into the SPS. Its essential property would be an adjustable h variation near the isochronous regime to meet the requirements imposed by bunch compression at ejection. It would also be equipped with all the correction systems of a modern machine. research-article