H. Braun

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^-

In this paper we discuss a new approach to two-beam acceleration. The energy for RF production is initially stored in a long-pulse electron beam which is efficiently accelerated to about 1.2 GeV by a fully loaded, conventional, low frequency (∼1 GHz) linac. The beam pulse length is twice the length of the high-gradient linac. Segments of this long pulse beam are compressed using combiner rings to create a sequence of higher peak power drive beams with gaps in between. This train of drive beams is distributed from the end of the linac against the main beam direction down a common transport line so that each drive beam can power a section of the main linac. After a 180-degree turn, each high-current, low-energy drive beam is decelerated in low-impedance decelerator structures, and the resulting power is used to accelerate the low-current, high-energy beam in the main linac. The method discussed here seems relatively inexpensive, is very flexible and can be used to accelerate beams for linear colliders over ...

Linear Collider Based on CLIC Technology

The drive beam of CTF II can provide single electron bunches with charges of more than 15 nC and rms lengths of less than 0. 13mm. If the bunches are bent in the dipoles of a magnetic bunch compressor, they emit coherent synchrotron radiation with strongly enhanced intensity with respect to incoherent synchrotron radiation. Here we report on the experimental and theoretical study of the effect of this coherent radiation emission on the distribution of the electrons in the six-dimensional phase space. Transverse emittances, bunch lengths, and energy spectra were measured for constant bunch compression ratios but different horizontal beam sizes in the bunch compressor. Further, the shielding effect of the finite vacuum chamber height on the mean beam energy loss was investigated by using two vacuum chambers of different heights in a four-magnet chicane. The results are compared with simulations using TraFiC/sup 4/ and ELEGANT.

A new method for RF power generation for two-beam linear colliders

We discuss the RF system, the drive linac, drive beam generation, the isochronous ring drive beam scheme, the main linac injector system, machine parameters, beam dynamics and final focus studies and the alignment test facility and beam monitor test results.

Recent experiments on the effect of coherent synchrotron radiation on the electron beam of CTF II

New parameters of an e⁺/e^-Linear Collider based on CLIC technology for a luminosity of 7·³⁴cm^-2s^-1at a nominal energy of 3 TeV are presented. They are derived in part from the very successful tests and experience accumulated in the CLIC Test facility, CTF2. A new and ambitious test facility, CTF3, presently under construction at CERN in an international collaboration of laboratories and institutes, and aimed at demonstrating the key feasibility issues of the CLIC scheme, is described.

CLIC-a compact and efficient high energy linear collider

Recent experimental results on normal conducting RF structures indicate that the scaling of the gradient limit with frequency is less favourable than was believed. We therefore reconsider the optimum choice of RF frequency and iris aperture for a normal conducting, two-beam linear collider with E/sub CMS/=3 TeV, a loaded accelerating gradient of 150 MV/m and a luminosity of 8/spl middot/10/sup 34/cm/sup -2/s/sup -1/. The optimisation criterion is minimizing RF costs for investment and operation with constraints put on peak surface electric fields and pulsed heating of accelerating structures. Analytical models are employed where applicable, while interpolation of simulation program results is used for the calculation of luminosity and RF structure properties.

Clic Progress Towards Multi-TeV Linear Colliders

The objectives of the CLIC Test Facility (CTF) are to study the generation of short intense electron bunches using a laser driven photocathode in an RF gun, to generate 30 GHz RF power for high gradient tests of prototype CLIC components, and to test beam position monitors. The performance of the CTF has improved dramatically in the course of the past year and highlights are presented.

Optimum choice of RF frequency for two beam linear colliders

Abstract The feasibility of a CLIC–LHC-based FEL–nucleus collider is investigated. It is shown that the proposed scheme satisfies all requirements of an ideal photon source for the nuclear resonance fluorescence method. The tunability, monochromaticity and high polarization of the FEL beam together with high statistics and huge energy of LHC nucleus beams will give a unique opportunity to determine different characteristics of excited nuclear levels. The physics potential of the proposed collider is illustrated for a beam of Pb nuclei.

CLIC Test Facility developments and results

The feasibility of a CLIC-LHC based FEL-nucleus collider is investigated. It is shown that the proposed scheme satisfies all requirements of an ideal photon source for the Nuclear Resonance Fluorescence method. The physics potential of the proposed collider is illustrated for a beam of Pb nuclei.

CLIC–LHC-based FEL–nucleus collider: Feasibility and physics search potential

The Compact Linear Collider (CLIC) Test Facility (CTF II) at CERN has recently demonstrated Two-Beam power production and acceleration at 30 GHz. With 41 MW of 30 GHz power produced in 14 ns pulses at a repetition rate of 5 Hz, the main beam has been accelerated by 28 MeV. The 30 GHz RF power is extracted in low impedance decelerating structures from a low-energy, high-current “drive beam” which runs parallel to the main beam. The average current in the drive-beam train is 25 A, while the peak current exceeds 2 kA. Crosschecks between measured drive-beam charge, 30 GHz power and main-beam energy gain are in good agreement. In this paper, some relevant experimental and technical issues on drive-beam generation, two-beam power production and acceleration are presented.