Preliminary study of gun emittance correction

The standard emittance calculation removes linear correlations between transverse displacement r and the divergence r´. Higher-order correlations remain, and they are responsible for a substantial area in phase space which corresponds to the calculated emittance. Time dependent correlations are identified, and a procedure is proposed to remove them. The Brookhaven National Laboratory radio frequency (RF) gun has been studied; however, in order to demonstrate the desired effects more clearly, the accelerating field and bunch length have been assumed to be more optimistic than the present operating values. This approach reduces the realizable emittance by a factor of 5 with respect to the value before the correction