• S. Matsumoto, M. Akemoto, T. Higo, H. Honma, M. Ikeda, K. Kakihara, T. Kamitani, H. Nakajima, K. Nakao, Y. Ogawa, S. Ohsawa, Y. Yano, K. Yokoyama, M. Yoshida
  KEK, Ibaraki

In order to improve the positron beam intensity needed for super KEKB project, it was decided to replace the present S-band structures in the positron capture section by a new L-band (1298MHz) accelerator system. 　A 2m long TW structure of 12MV/m gradient is now under idesign process while a　40MW klystron will be delivered in summer. After the klystron testing, a single L-band accelerator unit will be constructed for the structure study. The study is scheduled in next spring to operate the structure under solenoidal magnetic focussing field.

• T. Kamitani, M. Akemoto, D.A. Arakawa, A. Enomoto, S. Fukuda, K. Furukawa, T. Higo, H. Honma, K. Hosoyama, N. Iida, M. Ikeda, E. Kadokura, K. Kakihara, H. Katagiri, M. Kikuchi, Y. Kojima, M. Kurashina, S. Matsumoto, T. Matsumoto, H. Matsushita, S. Michizono, K. Mikawa, T. Mimashi, T. Miura, H. Nakajima, K. Nakanishi, K. Nakao, Y. Ogawa, S. Ohsawa, T. Sanami, M. Satoh, T. Shidara, A. Shirakawa, T. Sugimura, T. Suwada, T. Takenaka, M. Tawada, Y. Yano, K. Yokoyama, M. Yoshida
  KEK, Ibaraki

The KEKB-factory will be upgraded for 40 times higher lumnosity (SuperKEKB). The injector linac is required to increase the beam intensities (e-:1nC -> 5nC, e-:1nC -> 4nC) and reduce the emittances (e-:300 -> 20 um, e+: 2100 -> 10 um ) for the SuperKEKB. A photo-cathode RF gun will be introduced to generate the high-intensity and low-emittance electron beams. A positron damping ring will be constructed to reduce the emittance. A new matching device (a flux concentrator or a superconducing magnet) and an L-band capture section will be introduced to increase the positron intensity. Beam line layout down to the damping ring will be rearranged to have sufficient beam acceptance considering the positron emitttance. This paper describes details of the upgrade scheme of the injector linac.