ATF2 Proposal

This document is the first of two volumes describing the ATF2 project. The present volume discusses the technical justification for ATF2 and presents a design description. Since the International Committee for Future Accelerator (ICFA) decision on the choice of technology, a world-wide collaboration on the design of the International Linear Collider (ILC) has rapidly progressed [1]. The formation of the Global Design Effort (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. Accelerator Test Facility (ATF) at KEK was built to create small emittance beams, and succeeded in obtaining an emittance that almost satisfies the ILC requirements [2]. In this proposal we present a project, ATF2, which addresses the focusing of the beam into a nanometer spot. 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. The layout is shown in Figure 1.1. In the longer term, the ATF2 project would also provide invaluable input for the CLIC design of a future multi-TeV collider

ATF2 Proposal

A decade of dedicated R&D at KEK, DESY, CERN, SLAC and other laboratories were crucial to the successful development of the concepts for a linear collider and for demonstrating that the technical goals are achievable. We are now entering the global design phase for the ILC, and test facilities, demonstration experiments and fundamental R&D will continue to be very important to helping us develop the best possible ILC design, and one that employs forward looking technology.The ATF2 builds on the considerable investment, success and strong team that were responsible for the ATF. The new features provided by ATF2 will enable us to embark on a program to test the very demanding beam delivery requirements for the ILC. In addition, this project has the feature that it is being planned and executed internationally. Therefore, it represents a useful testing ground for managing and executing a complex international accelerator project

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.<br