Report of the International Study Group on future accelerators and high energy physics Serpukhov, 17-25 may 1976

regional facilities. This complex is likely to be of such a cost as to be beyond the capabilities of any single region. Examples include facilities such as a proton acceleratoro of energy higher than 10 TeV and an electron-positron colliding beam facility of more than 200 GeV in the center-of-mass. In this connection several conceptual designs of that kind were presented and discussed. In seeking to attain the more intensive internationl collaboration which is a fundamental prerequisite for progress toward the stated objectives, the Study Group recommends that the Internantional Union of Pure and Applied Physcis (Particles and Fields Division) be asked to initiate appropriate activities to this end. The seminar "Perspectives in High Energy Physics" held in New Orleans, March 1975, established a Study Group to discuss the long-range requirements for facilities in High Energy Physics. A sub-group met in CERN, October 1975, and planned an Agenda for a meeting which was held in Serpukhov, U.S.S.R. in May, 1976. In this paper a summary of the work done in Serpukhov is given. It begins with a review of the status of our present knowledge of the fundamental structure of matter and a statement of those future problems which can be clearly identified now and which will require new facilities for their solution. This is followd by a brief description of the status of today's accelerator technology and a review of projects that are now under active study as regional facilities. The study group has noted the need for close collaboration during the selction of the range of new regional facilities to ensure coverage of the broadest possible program of reserch. Included in this range may be a proton fixed target accelerator of up to several TeV, colliding beam facilities with a center-of-mass energy of up to several TeV for protons against protons, up to several hundred GeV for electrons against protons, and up to about 200 GeV for electrons against positrons. The participants have emphasized the importance of joint utilization of all such facilities by Physics will require in the future the development o an accelerator complex significantly more powerful than those planned for