Review of Electron-Positron Linear Colliders

Abstract

In June 1994 at EPAC 94 in London, the International Council of the Interlaboratory Collaboration of R&D Towards TeV-scale Electron-Positron Linear Colliders created an International Technical Review Committee (TRC) consisting of close to sixty scientists, and charged it with producing a report bringing together in one document all the ee linear collider designs and technologies in the world. The machines to be studied and compared were to start at c.m. energies of 500 GeV and have expansion capability to 1 TeV and above. The report [1] was completed in December 1995. The author of this paper was Chair of the TRC, T. Weiland represented the Secretariat, and E. Mitchell at SLAC was in charge of production. The TRC report is 186 pages long and only some of the highlights can be summarized here. The particle physics community has been greatly interested in such an accelerator for some years, and, if anything, this interest has grown with the decision to proceed with the LHC. Indeed, these two machines are highly complementary in what they can contribute to the field. The linear collider will be a precision tool to study t t production at threshold and above. If the Higgs and/or supersymmetric particles exist, the linear collider will be instrumental in discovering and/or studying them. If none of these particles exist, the machine will make it possible to explore other mechanisms to explain electroweak symmetry breaking. These are some of the most burning issues to be elucidated in the next few years. The ee linear collider also has the potential of producing exciting physics from ee, eγ and γ γ collisions, and of involving other applications such as FEL’s and other technologies. The TRC report consists of six chapters. The first chapter is a description of six machines at 500 GeV c.m. energy: TESLA, SBLC, JLC (S-, Cand X-band), NLC, VLEPP and CLIC. The second chapter includes the reports of six working groups respectively describing and comparing Injection Systems, Damping Ring and Compression Systems, Linac Technology, Beam Dynamics, Beam Delivery and Experimentation for the various machines. The third chapter describes methods proposed for each machine to upgrade their c.m. energies to 1 TeV and to obtain ee, eγ and γ γ collisions. Chapter 4 describes on-going experiments and test facilities, Chapter 5 discusses present and future areas of collaboration, and Chapter 6 presents conclusions. Given that this conference is devoted primarily to linacs, the emphasis in this paper is focused on this subject.