Jean-Christophe Peffen
European Synchrotron Radiation Facility
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Featured researches published by Jean-Christophe Peffen.
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment | 2002
Christian Morawe; Eric Ziegler; Jean-Christophe Peffen; Igor V. Kozhevnikov
Abstract We present first experimental results on the fabrication and characterization of depth-graded X-ray multilayers providing a broad and well-defined reflectivity profile. Following a theoretical approach including analytical and numerical techniques we have designed and deposited multilayer structures with a practically constant reflectivity of about 20% around the first Bragg-reflection and a bandwidth of about 20% in both incident angle and photon energy. A precise characterization using numerical simulations allows the determination of residual errors in the structure, which can appear during or after the coating process. The discussion includes practical issues and technical limitations of the deposition process as well as novel applications in modern X-ray optics.
International Symposium on Optical Science and Technology | 2001
Christian Morawe; Jean-Christophe Peffen; Eric Ziegler; Andreas K. Freund
Presently there is a gap in energy resolution (Delta) E/E between a few percent for multilayer x-ray optics and a few 10-4 for perfect crystal optics. One approach to bridge this gap is the development of high-resolution multilayers. We will report on recent advances in this field and discuss both the capabilities and the limitations of this solution. The deposition of hundreds of layers of hard materials is a considerable challenge for the coating system, and stability issues have to be considered with particular care. We have shown theoretically and experimentally that this challenge can be met with a combination of Al2O3 and B4C. With 680 bilayers we reached a spectral resolution < 0.3% and a peak reflectivity of almost 50% for 12 keV x- rays. The disagreement with the diffraction properties of a perfect multilayer system could be accurately described by instabilities during the deposition process. With improved stability, such systems can provide still better performances.
SPIE's International Symposium on Optical Science, Engineering, and Instrumentation | 1999
Christian Morawe; Jean-Christophe Peffen; Olivier Hignette; Eric Ziegler
Hard x-ray focusing devices based on laterally graded multilayers are key elements to fully exploit the advantages of third generation synchrotron sources. We have developed a design method to produce laterally graded multilayers using sputter deposition techniques. The multilayers are adapted to the given application by the proper choice of layer materials, d spacing, and the partition of the two constituent materials. The optimization of all relevant parameters yields an ab initio estimation of the desired layer thickness gradient. The performance and the accuracy of this method are demonstrated. The experimental lateral thickness errors could be reduced below 0.5% RMS over a total length of 300 mm. Reflectivity measurements at different energies are in good agreement with theoretical simulations. During focusing experiments at 13 keV a spot size of 1 micrometer and a gain in flux of 1000 were achieved.
Proceedings of SPIE | 2005
Christine Borel; Christian Morawe; Eric Ziegler; Thierry Bigault; Jean-Yves Massonnat; Jean-Christophe Peffen; Emilie Debourg
Periodic multilayers deposited by Distributed Electron Cyclotron Resonance (DECR) sputtering were studied with synchrotron radiation at the ESRF bending magnet beam line BM5. In situ reflectivity measurements at a photon energy of 20keV have been carried out on these samples during a specific heat treatment. A dedicated furnace has been developed to heat the multilayers under vacuum from room temperature up to 550°C. [Ru/B4C]70 and [W/B4C]40 samples with repetition periods of about 4nm were chosen. Simulations of reflectivity measurements were performed to understand the evolution of layer thicknesses and interface widths. Additional ex-situ reflectivity measurements were done at 8keV before and after the annealing experiments to investigate irreversible effects. We will discuss the heat impact on the layered structure and in which way multilayer optics could be thermally pre-treated before their installation on synchrotron beam lines.
International Symposium on Optical Science and Technology | 2001
Christian Morawe; Jean-Christophe Peffen; Eric Ziegler; Andreas K. Freund
To fill the gap in energy resolution dE/E between a few percent for multilayer x-ray optics and a few 10-4 for perfect crystal optics we have developed narrow bandpass multilayers consisting of Al2O3 and B4C layers. Their resolving power was precisely determined on the ESRF bending magnet beamline BM5 using a white beam and a Si(111) analyzer crystal. Scans in the (n,+m) and in the (n,-m) scattering geometry return consistent results. With a sample of 680 double layers we have obtained a spectral resolution of 0.27% at energies around 12 keV which is in good agreement with earlier studies using monochromatic x-rays.
Optical Science and Technology, SPIE's 48th Annual Meeting | 2003
Christian Morawe; Jean-Christophe Peffen; Eric M. Dufresne; Yong S. Chu; Albert T. Macrander
We have designed and fabricated a new type of focusing multilayer mirror, capable of reflecting a divergent beam over a large energy band around 9 keV. A flat energy response about 10% wide and providing a reflectivity of 50% has been achieved by a non-periodic bi-layer sequence while a lateral thickness gradient follows the varying Bragg condition over the whole mirror length. The focusing setup is based on a simple one-point bender and a pre-shaped substrate. A focal spot size of about 8 micrometers has been obtained at a distance of 285 mm from the center of the mirror using synchrotron radiation from an undulator source. Energy dependent scans have shown that this device enables focusing experiments with fixed geometry at variable energies.
Proceedings of SPIE | 2014
Xianchao Cheng; Christian Morawe; Jean-Christophe Peffen; Lin Zhang
Under synchrotron radiation white beam exposure, strong mechanical stress can build up in multilayer optics, caused by the thermal mismatch between layer material and substrate material. To study the stability and performance of multilayer optics under heat load, Pd, Cr, and B4C single layers of thicknesses in the nanometer range and [Pd/B4C] multilayers were prepared in the sputter-depositing facility of the ESRF Multilayer Laboratory. Curvature changes versus temperature were measured using a Shack-Hartmann wave front sensor. Films coated on 200 μm thin Si wafers induced significant curvature changes over a temperature range from 60°C to 200°C. A combined parameter K including Young’s modulus and thermal expansion coefficient (CTE) was defined to describe the thermal deformation properties of the thin-film layer. The investigation shows that all three materials in thin film cause less thermal expansion than expected from material properties for bulk material in the literature. In particular, the thermal expansion of B4C films appears to be close to that of the Si substrate.
Optical Science and Technology, the SPIE 49th Annual Meeting | 2004
Christian Morawe; Christine Borel; Eric Ziegler; Jean-Christophe Peffen
We present the theoretical design, the fabrication, and the performance of double gradient multilayers to be installed on a Kirkpatrick-Baez focusing system for the ESRF bending magnet beam line BM5. The lateral and the depth gradient of the two coatings were chosen in such a way as to obtain a flat reflectivity response of about 25% after two reflections over an energy range from 12keV to 14keV and at an angle of incidence of 0.5deg at the mirror center. Both mirrors were coated with a non-periodic Ru/B4C structure containing 71 individual layers. The overall depth gradient was identical for both multilayers and optimized at the mirror center while the lateral gradient was adapted to the different focal lengths of each of the two KB elements.
1994 International Symposium on Optical Interference Coatings | 1994
Peter Hoghoj; Eric Ziegler; Eike Lueken; Jean-Christophe Peffen; Andreas K. Freund
Distributed electron cyclotron resonance (DECR) plasma sputtering was used for depositing W/Si multilayers for x-rya optics. The argon plasma used in the sputtering process was excited by the DECR method. The DECR argon plasma diffusing the middle of the deposition chamber was characterized with a Langmuir probe. The ionization rate was found to be 7 X 10-4. This allowed us to sputter W and Si with a large range of target bias values at low pressures. Deposited single layers and W/Si multilayers were characterized with grazing incidence x-ray reflectometry. As an illustration of the capabilities, data is shown for a W/Si multilayer with period d equals 3.0 nm and an interface roughness (sigma) < 0.47 nm.
Advances in X-Ray/EUV Optics and Components XIII | 2018
Christian Morawe; Jean-Christophe Peffen; Phakkhananan Pakawanit
The ESRF Multilayer Laboratory has been operating a thin film x-ray reflectometer for more than 20 years. It is a critical piece of equipment needed to calibrate the multilayer deposition system and to characterize thin film based optical elements. The previous instrument had a number of drawbacks such as limitations in sample size and weight. In addition, the outdated control electronics had to be replaced. The new x-ray reflectometer was designed to handle up to 1 m long samples with a weight of 40 kg while maintaining a positioning accuracy of a few micrometres. The instrument includes a Cu K alpha micro-focus source followed by a Montel multilayer collimator. It can be operated in monochromatic or pink mode by inserting or removing a channel cut crystal monochromator. This work will give an overview on the mechanical and optical design. It will summarize performance benchmarks and give examples of measured x-ray spectra.