MEASUREMENT OF INJECTION ENERGY MISMATCH IN CIRCULAR ACCELERATORS USING RF CAPTURE EFFICIENCY OBSERVATIONS

A general method for measuring the energy mismatch between a storage r ing and its injector is presented. The energy mismatch is defined as t he difference between the injector energy and the synchronous energy o f the storage ring. Observations of the rf capture of the injected bea m when the energy acceptance or synchronous energy are varied yield th e energy mismatch. The energy acceptance and synchronous energy are ea sily varied by changing the rf accelerating voltage, the rf frequency, or both. As an example, measurements performed on the 1 GeV electron storage ring Aladdin show an energy mismatch of 0.666 MeV at the injec tion energy of 108 MeV. This agrees with theoretical predictions about injection stacking at a rate faster than the radiation damping rates.