Measurements of the beam emittance during bunch compression in the CLIC Test Facility (CTF-II) are described. The measurements were made with different beam charges and different energy correlations versus the bunch compressor settings which were varied from no compression through the point of full compression and to overcompression. Significant increases in the beam emittance were observed with the maximum emittance occurring near the point of full (maximal) compression. Finally, evaluation of possible emittance dilution mechanisms indicates that coherent synchrotron radiation was the most likely cause. PACS numbers: 29.27.Bd, 41.60.Ap, 41.75.Lx Magnetic bunch compressors have been and will be utilized in many high-energy electron accelerators to increase the longitudinal density of a particle beam. In particular, they are important in linear colliders, where short bunches are needed because of the short depth of focus at the interaction point, and in short wavelength FELs, where high peak current is needed to reduce the optical gain length.The compressors operate by first creating an energy variation along the length of the bunch and then passing the bunch through a series of bending magnets in which the path length is energy dependent. By appropriately choosing the energy correlation and magnet strengths, the bunch can be compressed as desired and, because the forces involved are conservative, the longitudinal and transverse phase-space densities should be conserved.The conservation of the transverse phase-space density, referred to as the transverse beam emittance, is usually of extreme importance-this is especially true in linear colliders and short wavelength FELs whose performance is very sensitive to the transverse emittances. There are a number of sources of emittance dilution which can increase the emittances, decreasing the phase-space density. The most obvious are chromatic effects that are important because of the large energy spread (typically a few percent) that is needed to compress the bunch length; thus the compressor optics are usually achromatic to second or higher order. Other standard sources of dilution include the longitudinal wakefields and the "classical" longitudinal space charge force which is inversely proportional to the square of the beam energy 1͞g 2 ; these break the achromaticity of the optics by generating small energy changes within the compressor.Recently, as designs have started requiring shorter bunches and smaller emittances, the more subtle issue of what happens as the beam is deflected in the bending magnets has been discussed. This includes the transformation of the longitudinal space charge force in the curved geometry [1] as well as the coherent synchrotron radiation [2-6]. The resulting emittance dilution, which is independent of the beam energy, appears to place very stringent limits on many of the future bunch compressor designs. Coherent synchrotron radiation itself has been observed in special experiments [7,8], but, at this time, the effect on the beam has no...

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SPIRAL, the Radioactive Ion Beam (RIB) Facility at GANIL, Caen will use the high intensity, heavy ion beams of GANIL for the production of radioactive species by the ISOL method.The Radioactive Beams produced by the target and source assembly, will be accelerated up to a maximum energy of 25 MeV/u by the new cyclotron CIME. Preliminary tests of CIME with stable ions were presented in the previous cyclotron conference at Caen in 1998. Since then, important progress were made in the commissioning of CIME. They are presented in this paper as well as the present status of the delivery of the administrative authorizations which are needed for the production of the first radioactive beams by the facility.

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In order to test the principle of Two-Beam-Acceleration (TBA), the CLIC Test Facility utilizes a high-intensity drive beam of 640 to 1000 nC to generate 30 GHz accelerating fields. To ensure that the beam is transported efficiently, a robust measurement of beam emittance and Twiss parameters is required. This is accomplished by measuring the beam size on a profile monitor, while scanning five or more upstream quadrupoles in such a fashion that the Twiss parameters at the profile monitor remain constant while the phase advance through the beam line changes. In this way the beam size can be sampled at different phases while a near-constant size is maintained at the profile monitor. This eases many of the difficulties of such measurement devices, especially those associated with limited dynamic range. In addition, the beam size is explicitly constant for a matched beam, which provides a "nulling" measurement of the match. Details of the technique, simulations, and results of the measurements are discussed.