For Layout of ILC , revised K.Kubo Based on following choices. Positron source: Prepare both conventional and undulator based. Place the undulator at Ebeam = 150 GeV (USTOS) Damping Ring: Dogbone DR, sharing tunnel with Main Linac. Avoid DR - Main Linac interference in the first stage. (Oide - scheme) Turn Around: 180 degree turn around after damping rings. This scheme allows orbit feed-forward. Two alternative plans without undulator are also shown. Layout of the interaction region can be the same as in GLC Road Map report, tentatively. Numbers with ‘?’ should be re-considered or reviewed by experts.

Electron main linac Electron main linac for energy upgrade Positron capture and accelerator Positron transfer line Undulator IPs Electron damping ring Electron injector Collimator and final focus Positron main linac Positron main linac for energy upgrade Low emittance electron transfer line Low emittance positron transfer line Positron damping ring Conventional positron source and injector Positron transfer line IPs Collimator and final focus Schematic Layout of Beam Line (Conventional and Undulator e+ source)

e+ main linac (20.2 km) e+ DR (Straight section 7 km) e- DR (Straight section 7 km) e- main linac (21.2 km) e+ BDS (1.9 km) e- BDS (1.9 km) Undulator e+ source, 5 GeV Linac (total ~ 1km) Spin rotator + Bunch compressor Detector halls Dump halls Schematic Layout and length of each part e- source e- 5GeV Linac (total 400 m) e+ sourece, e+ 5 GeV Linac (total 1 km) Turn around 6.1 km

e+ DR e- DR Energy upgrade scheme No DR-ML interference in the first stage. (Oide - scheme) Main Linac from the beginning Main Linac for upgrade to 1 TeVMain Linac from the beginning Main Linac for upgrade to 1 TeV Electron Positron IP

Damping Ring geometry (similar to TESLA-TDR) 3.5 km Center point. Left side is 180 degree rotation symmetry

Damping Ring Arc region by US Technical Option Study

5 GeV Electron Injector Linac + Spin Rotator (total 400 m) Electron Main Linac Electron Damping Ring Electron Injection to Damping Ring Utility Tunnel Electron Injector Main Linac DR Transfer line Positron transfer line

Utility Tunnel Or, may be Electron Injector Main Linac DR Transfer line

Electron Main Linac Electron Damping Ring Electron Extraction from Damping Ring Low emittance 5 GeV electron transfer line Spin Rotator + Bunch Compressor (400 m?) Positron transfer line

Positron Main Linac Positron Damping Ring Positron Injection to Damping Ring 5 GeV positron transfer Line (undulator base) Electron linac + Target + capture section + Positron Injector Linac (Total 1000 m, conventional ) Utility Tunnel Injector Tunnel Main Linac DR

Positron Main Linac Positron Damping Ring Bunch Compressor + Low Emittance 5GeV positron transfer line Positron Extraction from Damping Ring Extraction

Turn around (same geometry as DR) Electron (mirror symmetry for positron) Main Linac start

Undulator region (300 m) Positron production and capture (50 m?) Positron 5 GeV (may be lower) Linac (400 m) Electron Main Linac Chicane for positron production electron Low energy positron Transfer line Positron production (Undulator base) (same as USTOS) Electron beam energy =150 GeV 2.5 m 900 m

Schematic Layout of Positron Transfer in IP region (For Undulator based positron source) Detector Halls Main Bema lines Low energy e+ line (Horizontal detour) e- e+

Or, may be Detector Halls Main Bema lines Low energy e+ line (Vertical detour) e- e+

Alternative plan -1 (No Undulator e+ source, with Oide-scheme) Collimator and final focus IPs Positron main linac Positron main linac for energy upgrade Conventional positron source and injector Positron damping ring Low emittance positron transfer line Electron damping ring Collimator and final focus IPs Electron main linac for energy upgrade Electron main linac Electron injector Low emittance electron transfer line

Alternative plan -2 (No Undulator e+ source, without Oide-scheme) (Only electron line is shown. Positron line is similar.) Electron damping ring Collimator and final focus IPs Empty tunnel (free from operation) Electron main linac Electron injector Low emittance electron transfer line Electron damping ring Collimator and final focus IPs Electron main linac Electron injector Low emittance electron transfer line Ecm=500 GeV Ecm=1000 GeV