The CLIC project

Abstract

The Compact Linear Collider (CLIC) is a multi-TeV high-luminosity linear e + e − collider under development by the CLIC accelerator collaboration, hosted by CERN. The CLIC accelerator has been optimised for three energy stages at centre-of-mass energies 380 GeV, 1.5 TeV and 3 TeV [1]. CLIC uses a novel two-beam acceleration technique, with normal-conducting accelerating structures operating in the range of 70 MV/m to 100 MV/m. The report describes recent achievements in accelerator design, technology development, system tests and beam tests. Large-scale CLIC-specific beam tests have taken place, for example, at the CLIC Test Facility CTF3 at CERN [2], at the Accelerator Test Facility ATF2 at KEK [3,4], at the FACET facility at SLAC [5] and at the FERMI facility in Trieste [6]. Crucial experience also emanates from the expanding field of Free Electron Laser (FEL) linacs and recent-generation light sources. Together, they demonstrate that all implications of the CLIC design parameters are well understood and reproducible in beam tests and prove that the CLIC performance goals are realistic. An alternative CLIC scenario for the first stage, where the accelerating structures are powered by X-band klystrons, is also under study. The implementation of CLIC near CERN has been investigated. Focusing on a staged approach starting at 380 GeV, this includes civil engineering aspects, electrical networks, cooling and ventilation, installation scheduling, transport, and safety aspects. All CLIC studies have put emphasis on optimising cost and energy efficiency, and the resulting power and cost estimates are reported. The report follows very closely the accelerator project description in the CLIC Summary Report for the European Particle Physics Strategy update 2018-19 [7].

The carbon footprint of proposed $${\mathrm{e}}^+{\mathrm{e}}^-$$ Higgs factories

“…The annual energy consumption in operation, E, is calculated by multiplying the instantaneous power by the time spent in collisions T , to which is added for completeness the product of the time spent with the collider powered but not in collision mode ( T / − T , where is the operational efficiency) by the instantaneous power in that mode, assumed to be half of the full power. This seemed to validate the second proposition, at least until the recent CLIC performance update [9] was made public.…”

“…In July 2022, the Snowmass'21 effort held its last public meeting in Seattle [5], and the Energy Frontier working group came to similar general conclusions [6], pending the P5 recommendations and the subsequent DoE decision: after the immediate future (HL-LHC), the intermediate future is an e + e − Higgs factory, based on either a linear (ILC in Japan [7], C 3 in the US [8], CLIC at CERN [9]) or a circular (FCC-ee at CERN [10], CEPC in China [11]) collider, and the long-term future is a multi-TeV (μμ and/or pp) collider.…”

RF Technologies for Future Colliders

“…Among the potential next-generation SRF colliders are the International Linear Collider (ILC) [9], recently proposed HELEN collider [10], and two concepts based on energy recovery linacs: ERLC [11] and ReLiC [12]. The normal-conducting RF linacs are utilized in the Compact Linear Collider (CLIC) [13] and Cool Copper Collider (C 3 ) [14] proposals. In this section, state of the art for the two linear collider technology options and ongoing R&D are considered.…”

“…Two normal conducting linear colliders are being actively developed at present: Compact Linear Collider (CLIC) [13] and Cool Copper Collider (C 3 ) [14]. To limit average power dissipation in the cavity walls at high accelerating gradients, normal conducting structures must operate in the pulsed mode with very short pulses.…”

“…The CLIC [13] has been optimized for three center-of-mass energies: 380 GeV, 1.5 TeV, and 3 TeV. It utilizes a novel twobeam acceleration technique.…”