• 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.

• S. Ushijima, H. Fujisawa, Y. Iwashita, H. Tongu
  Kyoto ICR, Uji, Kyoto
• M. Masuzawa, T. Tauchi
  KEK, Ibaraki

A permanent magnet quadrupole lens with continuously adjustable strength originally designed by Gluckstern was fabricated for a final focus. It consists of five PMQ discs that rotate on their axis, where odd and even numbered discs rotate oppositely but with the same absolute angle. By setting their lengths appropriately, the coupling between x and y components can be minimized. In order to reduce multipole components higher than quadrupole, we adjust positions of magnet wedge pairs. At the same time we improve differences between the magnetic center and the mechanical center of the PMQ discs by measuring harmonics of fields in magnets. In order to carry out the beam test, a high precision movable table for the lens system is also fabricated. This table can evacuate the lens system from the beam line completely without vacuum breaking, which should ease the evaluation of the system at decreased strength region.