I. Syratchev

A 3 TeV

A possible design of a multi-TeV e+e- linear collider is presented. The design is based on the CLIC (Compact Linear Collider) two-beam technology proposed and developed at CERN. Though the study has shown that this technology is applicable to a linear collider with centre-of-mass energies from 500 GeV or less up to 5 TeV, the present report focuses on the nominal energy of 3 Te V. First, a short overview is given of the physics that could possibly be done with such a collider. Then, the description of the main-beam complex covers the injection system, the 30 GHz main linac, and the beam delivery system. The presentation of the RF power source includes the beam-generation scheme, the drive-beam decelerator, which consists of several 625 m long units running parallel to the main linac, and the power-extraction system. Finally, brief outlines are given of all the CLIC test facilities. They cover in particular the new CLIC test facility CTF3 which will demonstrate the feasibility of the power production technique, albeit on a reduced scale, and a first full-scale single-drive-beam unit, CLICI, to establish the overall feasibility of the scheme.

e^+ e^-

One priority of the CLIC (Compact Linear Collider) accelerating-structure development program has been to investigate ways to achieve accelerating gradients above 150 MV/m. Two main concepts to achieve such high gradients have emerged: reduced surface field geometries and the use of alternative materials. An experimental demonstration of these two concepts has been made in CTFII (CLIC Test Facility) using three 30 GHz accelerating structures: one made entirely from copper, one with copper cavity walls and tungsten irises and one with copper cavity walls and molybdenum irises. A peak accelerating gradient of over 190 MV/m was achieved using the molybdenum-iris structure. The effect of pulse length on achievable gradient was investigated using a novel pulse stretcher.

Linear Collider Based on CLIC Technology

Accelerating structures with strong transverse-mode damping are required in both the 30 GHz CLIC main linac and the 3 GHz CTF3 drive-beam accelerator. Damping via slotted irises has been investigated for both structures. The transverse wake, the effect of the slots on the fundamental-mode parameters such as Q, sensitivity to tolerances, and surface-field enhancements have been computed. Terminating loads have been designed and machining studies to obtain rounded slot edges have been made. A 32-cell prototype 3 GHz structure is being fabricated for the drive beam accelerator of CTF3.