HIGH-INTENSITY AND LOW-EMITTANCE UPGRADE OF 7-GeV INJECTOR LINAC TOWARDS SuperKEKB

After a decade of successful operation at KEKB a new asymmetric electron/positron collider, SuperKEKB, is being constructed upgrading KEKB. It aims at a luminosity of 8× 10 cm s, 40-times higher than that of KEKB, in order to study the flavor physics of elementary particles further, by mainly squeezing the beams at the collision point. The injector linac should provide high-intensity and lowemittance beams of 7-GeV electron and 4-GeV positron by newly installing a RF-gun, a flux concentrator, and a damping ring with careful management of emittance and energy spread to be 20 mm mrad and 0.1%. It should also perform simultaneous top-up injections into four storage rings by pulse-to-pulse beam modulations not to interfere between three facilities of SuperKEKB, Photon Factory and PF-AR. This paper describes the injector design decisions and present status of the construction. SuperKEKB will be commissioned within FY2014