Transition radiators for electron identification at the CERN ISR

The authors describe transition radiators constructed from thin foils of lithium, used to separate electrons from heavier charged particles at the CERN Intersecting Storage Rings (ISR). The optimisation of the system of the radiator and detector is discussed, leading to the choice of parameters for this design. The special features of the construction of a structure of lithium is described. Results of a number of different measurements of the transition radiation are given. (11 refs).