ATF2 Proposal: v.1

Since the ICFA decision on the choice of technology, a world-wide collaboration on the design of the ILC has rapidly progressed. The formation of the GDE will accelerate the work towards a final design. An important technical challenge is obviously the high gradient acceleration but what is similarly challenging is the collision of extremely small beams of a few nanometer size. The latter challenge has three distinct issues: creating small emittance beams, preserving the emittance during acceleration and transport, and focusing the beams to nanometers. Most studies have been done using computer simulations but many issues still remain that require experimental verification. KEK-ATF was built to create small emittance beams, and succeeded in obtaining an emittance that almost satisfies the ILC requirements. In this proposal we present a project, ATF2, which addresses the third issue, namely the focusing of the beam into nanometer spot.ybr> In the longer term, the ATF2 project would also provide invaluable input for the CLIC design of a future multi-TeV collider. The ATF2 project will extend the extraction beamline of the ATF with an ILC-type final focus system to create a tightly focused, stable beam by making use of the small emittance of the ATF.