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Abstract: The European Free Electron Laser (FEL) at ELETTRA has recently increased its maximum operating energy up to 1.5 GeV, the highest electron-beam energy used so far for an FEL. This is' an important improvement in the performance of the source, increasing the extracted power at wavelengths around 200 nm and providing better beam stability and lifetime. Furthermore, this development represents a first step towards the solution of a crucial issue-the compatibility of FEL and normal synchrotron radiation operation at a user facility like ELETTRA. In this paper we discuss the most important aspects of this issue; in particular, we show that the properties of the electron beam in FEL mode can match the needs of normal synchrotron radiation experiments that require a few bunch filling of the storage ring. (C) 2003 Published by Elsevier Science B.V.

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Abstract: The local adsorption geometry of CO adsorbed in different states on Ni(1 0 0) and on Ni(1 0 0) precovered with atomic hydrogen has been determined by C 1s (and O 1s) scanned-energy mode photoelectron diffraction, using the photoelectron binding energy changes to characterise the different states. The results confirm previous spectroscopic assignments of local atop and bridge sites both with and without coadsorbed hydrogen. The measured Ni–C bondlengths for the Ni(1 0 0)/CO states show an increase of 0.16 ± 0.04 Å in going from atop to bridge sites, while comparison with similar results for Ni(1 1 1)/CO for threefold coordinated adsorption sites show a further lengthening of the bond by 0.05 ± 0.04 Å. These changes in the Ni–CO chemisorption bondlength with bond order (for approximately constant adsorption energy) are consistent with the standard Pauling rules. However, comparison of CO adsorbed in the atop geometry with and without coadsorbed hydrogen shows that the coadsorption increases the Ni–C bondlength by only 0.06 ± 0.04 Å, despite the decrease in adsorption energy of a factor of 2 or more. This result is also reproduced by density functional theory slab calculations. The results of both the experiments and the density functional theory calculations show that CO adsorption onto the Ni(1 0 0)/H surface is accompanied by significant structural modification; the low desorption energy may then be attributed to the energy cost of this restructuring rather than weak local bonding.

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Abstract: The Diamond timing system is the next generation development of the design, principles and technologies currently implemented on the Advanced Photon Source and Swiss Light Source. It provides the features to distribute events, RF clock and time stamps over the same medium. To support the required level of precision for distributing timing fiducials and clocks, the transmission will use higher bit rates (at least 2.5 Gbps). It is currently envisaged that OM3 multimode fibre optic cable will be used as a medium. A new 4 channel timer module will be designed, with a resolution better than 20 ps, for systems which require fine time tuning. The timing system will be controlled through the Diamond distributed control system which is based on EPICS.

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Abstract: A Michelson interferometer for X- rays of wavelength similar to 1 Angstrom has been proposed to test the temporal coherence of FEL radiation. Such a device has been made at HASYLAB from a silicon single crystal. It is based on the BBB interferometer of Bonse and Hart. One of its mirrors can be pushed by a piezo to introduce the desired beam path difference. For the preliminary tests described in this paper, the crystal was also equipped with an LLL interferometer to check the quality of the crystal and of its preparation. The rotation of a phase- shifting object ( a Plexiglas plate) in one of the LLL's beam paths has been found to produce a fringe pattern which can be shown to yield the phase- shifting material's index of refraction. The interferometer crystal's front section was held fixed with a compression spring. At the same time, the interferometer was bathed in viscous silicone oil to reduce vibrations.

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Abstract: The growth of platinum on a nickel ~111! single crystal under ultrahigh vacuum conditions was studied using surface x-ray diffraction on the ID03 beamline of the ESRF. Film thickness ranged from one to eight monoatomic layers ~ML!. Specular reflectivity was used to determine the growth mode and vertical lattice parameter of the Pt film. A two-dimensional ~2D! growth up to 1 ML followed by more 3D growth was found. A small expansion of the Pt vertical lattice parameter was found. The Pt in-plane lattice parameter was measured. Its relaxation was found to be very slow, with a residual contraction of 2.3% in an 8-ML-thick film ~with respect to bulk Pt!. A Ni crystal truncation rod measured before and after growing 1 ML of Pt revealed the presence of a small amount of pseudomorphic Pt, adsorbed on both fcc and hcp sites. The stacking of the ~111! Pt planes was investigated by measuring stacking-sensitive Pt diffraction rods. A strong tendency to stacking reversal was found at room temperature, with an amount of ‘ ‘reversed’’ Pt about ten times higher than the amount of Pt with the same stacking as the Ni. An eight-layer Ni film on Pt~111! was also studied for comparison