Injector for LEP

Two alternative 15 GeV injectors have been considered for the 15 to 100 GeV, four-bunch version of the e+e- storage ring LEP1: i) a synchrotron operating with four bunches and cycling at a rate of 0.4 Hz, and ii) a storage ring (SR) which is capable of holding the full charge of one LEP beam in 48 bunches. The e+ are slowly accumulated in the SR during running of LEP for high-energy physics experiments, i.e. prior to LEP's refill. The synchrotron system is designed to provide a ~15 min filling time of LEP; the SR would reduce it to ~5 min for a scheduled fill. The design considerations are outlined and the merits of the two systems are discussed.