Status and future directions for advanced accelerator research-conventional and non-conventional collider concepts

The relationship between advanced accelerator research and future directions for particle physics is discussed. Comments are made about accelerator research trends in hadron colliders, muon colliders, and e +e- linear colliders. COLLIDERS AND HIGH ENERGY PHYSICS The mass scale of interest to particle physics is the range of ~ 0.5 to 2 TeV where electroweak symmetry is broken. Experiments at colliders with high enough energy are expected to detect evidence of electroweak symmetry breaking and to shed light on the symmetry breaking mechanism. Is it the classic Higgs phenomena, supersymmetry, strong coupling, or something else? History suggests that discovering the origin of electroweak symmetry breaking will also raise questions about subjects unknown today. The Large Hadron Collider (LHC) is a technically proven and funded project that could reach high enough energy and luminosity for the study of electroweak symmetry breaking, and the NLC, JLC and TESLA, linear colliders being designed for center-of-mass energies E CM = 0.5 to 1.5 TeV, promise an unrivaled environment for the study of this phenomenon. The sizes and costs of these colliders raise questions that are at the heart of the future of particle physics 1. Are the colliders and detectors needed for the study of electroweak symmetry breaking affordable? The costs of these facilities are modest on the scale of many governmental activities, so the issue is whether our elected representatives decide that high energy physics pursued at this scale is or is not in the national interest. The SSC was started when they decided it was, but that project was terminated when their opinion changed. CERN and the LHC may be facing problems of the same nature with the discussion of budget cuts initiated by the German government. International collaboration on the design, construction and operation of large colliders is the proposed solution to the high cost of these facilities. The cost per country is reduced, but the involvement and commitment of each country is reduced also. Will one or two large colliders located somewhere in the world meet the needs of the governments that support particle physics, the institutions