RF gun development for SuperKEKB

The injector linac of KEK is being upgraded for SuperKEKB. High-charge low-emittance electron and positron beams are required for SuperKEKB. The required injection electron beam parameters are 7.0 GeV at 5 nC 20 mm-mrad. A thermal cathode DC gun had been used for KEKB. However the DC gun could not make low-emittance beam. Thus low-emittance new RF gun is being developed. We are developing an advanced RF gun which has two side coupled standing wave field. We call it quasi-traveling wave side couple RF gun. This gun has a strong focusing field at the cathode and the acceleration field distribution also has a focusing effect. This RF gun had been installed KEK linac. In addition another RF gun was installed to 90 deg injection line. These guns have been used for electron beam study. (author)