• A. Enomoto, S. Fukuda, K. Hosoyama, S. Imamura, H. Itoh, M. Miyahara, Y. Sugimoto, T. Tauchi
  KEK, Ibaraki

The international linear collider (ILC) project is about to meet the technical design phase 2, of which the goal is to establish a realistic design by the end of 2012. Single-tunnel accelerator configuration is one of the most essential improvements to reduce the construction costs. The original design involves two tunnels which house the accelerator cavities and the power supplies separately, having such advantages as we can enter the power-supply tunnel even during beam operation. Although the single tunnel configuration sacrifices these functions, it saves big tunnel construction costs. The Asian team is studying a regional single-tunnel accelerator configuration to match the Asian site feature in conjunction with a compact high-level RF scheme called distributed RF system (DRFS). The design concepts have been developed by a conventional facility working group in the advanced accelerator association (AAA) which involves a collaboration among academic, industrial, and political communities in Japan. Not only cost reduction but also functional impacts of tunnel configuration on things such as life safety are discussed in this paper.