CLIC (Compact Linear Collider) is a study for a future electron-positron collider that would allow physicists to explore a new energy region
in the multi TeV range beyond the capabilities of today's particle accelerators. It would provide significant fundamental physics information
complementary to the LHC and a lower-energy linear e+/e- collider, as a result of its unique combination of high energy and experimental precision (see CERN report 2004-05: Physics at the CLIC Multi-TeV Linear Collider).
Within the framework of a world-wide collaboration on Linear Colliders, the Compact Linear Collider (CLIC) study aims at a center-of-mass energy range for electron-positron collisions of 0.5 to 5 TeV, optimised for a nominal center-of-mass energy of 3 TeV (3 TeV CLIC). In order to reach this energy in a realistic and cost efficient scenario, the accelerating gradient has to be very high - CLIC aims at an acceleration of 100 MV/m. Superconducting technology being fundamentally limited to lower gradients, only room temperature travelling wave structures at high frequency (12 GHz) are likely to achieve this gradient.
In order to optimize the production of sufficient RF power for this high gradient, CLIC relies upon a
novel two-beam-acceleration concept: The 12 GHz RF power is generated by a high current electron beam (drive beam) running parallel to the main beam. This drive beam is decelerated in special power extraction structures (PETS) and the generated RF power is transfered to the main beam. This leads to a very simple tunnel layout without any active RF components (i.e. klystrons). Both beams can be generated in a central injector complex and are transported along the linac.
CLIC module layout
CLIC general layout
A number of challenges have to be mastered:
• the efficient generation of the high-intensity drive beam
• the Power Extraction Structures generating the required power
• the 12 GHz accelerating structures capable of producing the required gradient at a low rf breakdown rate
• the generation and preservation of a small emittance main beam
• the focusing of the beam to nanometre beam size
• the precise aligment of the different components.
Many key aspects of the CLIC scheme have been experimentally validated already in different test facilities (CTF, CTF2 and CTF3). The goal of the present CLIC Test Facility CTF3 is to demonstrate all the remaining CLIC specific key issues until 2010 to show the feasilbity of the CLIC scheme.
A detailed description of CLIC (with older parameters) can be found in the report CERN 2000-008 (pdf and ps versions), "A 3 TeV e+e- Linear Collider based on CLIC Technology". The latest revision of the layout and parameters can be found in CLIC note 764.