The drive beam pulse compression system for the CLIC RF power source

The Compact LInear Collider (CLIC) is a high energy (0.5 to 5 TeV) e ± linear collider that uses a high- current electron beam (the drive beam) for 30 GHz RF power production by the Two-Beam Acceleration (TBA) method. Recently, a new cost­effective and efficient generation scheme for the drive beam has been developed. A fully­loaded normal­conducting linac operating at lower frequency (937 MHz) generates and accelerates the drive beam bunches, and a compression system composed of a delay­line and two combiner rings produces the proper drive beam time structure for RF power generation in the drive beam decelerator. In this paper, a preliminary design of the whole compression system is presented. In particular, the fundamental issue of preserving the bunch quality along the complex is studied and its impact on the beam parameters and on the various system components is assessed. A first design of the rings and delay­line lattice, including path length tuning chicanes, injection and extraction regions is also presented together with the simulation results of the beam longitudinal dynamics

Overview of CLIC and CTF3

The CLIC study aims at the design of a high-energy (0.5-5 TeV), high luminosity e+e- linear collider, as a possible facility for the post-LHC era. The beams are accelerated using high-frequency (30 GHz) normal-conducting structures operating at high accelerating gradients to reduce the length and, in consequence, the cost of the linac. The RF power for these structures is generated using the so-called Two-Beam Acceleration (TBA) scheme, where a low-energy, high-intensity electron beam (drive beam) runs parallel to the main linacs and is decelerated in resonant structures, which extract RF power from the drive beam. The drive beam is first accelerated in a low-frequency fully-loaded normal-conducting linac. Its time structure is then obtained by funneling in isochronous rings using transverse RF deflectors. CTF3, a new generation CLIC Test Facility, is being built at CERN to demonstrate the technical feasibility of this novel drive beam generation and RF power production scheme, albeit on a much smaller scale. CTF3 will also constitute a 30 GHz source with the CLIC nominal peak power and pulse length, for RF component testing. In this paper we give an overview of the CLIC study, focusing on the most recent progress and describe the CTF3 status

An Overview of the New CLIC Test Facility (CTF3)

The CLIC (Compact Linear Collider) RF power source is based on a new scheme of electron pulse compression and bunch frequency multiplication, in which the drive beam time structure is obtained by the combination of electron bunch trains in isochronous rings. The next CLIC TEST Facility (CTF3) at CERN will be built in order to demonstrate the technical feasibility of the scheme. It will also constitute a 30 GHz source with the CLIC nominal peak power and pulse length, for RF component testing. CTF3 will be installed in the area of the present LEP preinjector (LPI) and its construction and commissioning will proceed in stages over five years. In this paper we present an overview of the facility and provide a description of the different components

CLIC Drive Beam and LHC Based Fel-Nucleus Collider

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.Comment: Presented at PAC05, 16-20 May 2005, Knoxville, TN, US

Electron beam combination by RF deflectors: Tolerance and requirements

In the framework of the new Compact Linear Collider (CLIC) Test Facility CTF3, it is planned to perform a demonstration of the bunch frequency multiplication process on which the CLIC drive beam generation scheme is based. This process relies on the combination of electron bunch trains in isochronous rings using RF deflecting cavities. Specific requirements are imposed on both the beam characteristics and the RF amplitude and phase in the deflectors. In this paper, we study and specify these requirements in the case of the Preliminary Phase of CTF3

Beam transverse stability in the CLIC combiner rings

The Compact Linear Collider (CLIC) RF power source is based on a new scheme of electron pulse compression and bunch frequency multiplication. In this scheme the drive beam time structure is obtained by the combination of electron bunch trains in isochronous rings using RF deflectors. One of the potential problems is the drive beam transverse stability in the rings, arising from beam resonant excitation of the electric field in the RF deflectors. In this paper numerical simulations are used to evaluate the effect and to show that the instability can be minimised by a proper choice of the tune of the ring, and of the parameters of the deflector and of the injection region lattice

The CLIC Multi-Drive Beam Scheme

The CLIC study of an e+ / e- linear collider in the TeV energy range is based on Two-Beam Acceleration (TBA) in which the RF power needed to accelerate the beam is extracted from high intensity relativistic electron beams, the so-called drive beams. The generation, acceleration and transport of the high-intensity drive beams in an efficient and reliable way constitute a challenging task. An overview of a potentially very effective scheme is presented. It is based on the generation of trains of short bunches, accelerated sequentially in low frequency superconducting cavities in a c.w. mode, stored in an isochronous ring and combined at high energy by funnelling before injection by sectors into the drive linac for RF power production. The various systems of the complex are discussed

A New Ultra-dense Group of Obscured Emission-Line Galaxies

We present the discovery of an isolated compact group of galaxies that is extremely dense (median projected galaxy separation: 6.9 kpc), has a very low velocity dispersion ($\sigma_{\rm 2D}$ = 67 km s$^{-1}$), and where all observed members show emission lines and are morphologically disturbed. These properties, together with the lack of spirals and the presence of a prominent tidal tail make this group one of the most evolved compact groups.Comment: 15 pages,LaTeX, 2figures. A Postscript figure with spectra is available at ftp://astro.uibk.ac.at/pub/weinberger/ . Accepted for publication in ApJ Letter