[en] The kind of optical components that have been developed over the centuries to make use of visible light won't work for x-rays. New ways must be found to manipulate the much shorter-wavelength x-ray beams to produce effects similar to those achieved with such familiar devices as mirrors, lenses, prisms, and gratings. This is the province of the field of x-ray optics. One challenge is to design optical elements that can focus, disperse, or reflect beams in the x-ray region of the electromagnetic spectrum, where wavelengths are about a thousand times shorter than those in the region of visible light. A second problem is encountered in using the intense, high-energy x-radiation from a synchrotron: how to make the desired beam accessible to a user who is conducting an experiment in a shielded enclosure many meters away from the synchrotron storage ring. Depending on the application, one might want to pick out a single wavelength from the broad spectrum available from the synchrotron, or isolate a narrow band of wavelengths. Then the beam must be collimated. When samples to be exposed are of millimeter dimension or smaller, it may be desirable to increase the intensity by focusing the x-ray beam horizontally and vertically. All these manipulations are analogous to those done with visible light, but the shape and form of the optical components can be quite different

[en] A new method of numerical calculation, based on geometrical optics for X-rays rather than ray-tracing, is developed to simulate the focal spot size and intensity gain from an elliptically-tapered one-bounce glass mono-capillary. Numerical results for a capillary designed for protein crystallography are in good agreement with experimental measurements and confirm a capillary slope errors limitation on the image quality

[en] In the period of the late-1980s, before the construction of multi-GeV third-generation storage rings with their intense insertion-device sources, the perceived number one problem for X-ray instrumentation was proper cooling of the first optical element in the beamline. This article, first given as an acceptance speech for the Compton Award ceremony at the Advanced Photon Source, presents a somewhat historical and anecdotal overview of how cryogenically cooled monochromator optics have been developed to provide a monochromator cooling solution adequate for today's power levels. A series of workshops and international collaborations were the key components for the progress and final success of this development

[en] A single, borosilicate-glass capillary was drawn into a 30.5 cm long elliptical shape. The inside diameter was 0.40 mm at the large base end and 0.13 mm at the tip. With 12 keV X-rays from the CHESS D1 bending magnet, the single-bounce capillary produced a focus of better than 18 μm in diameter (FHWM) at a 3 cm distance from the capillary tip. A flux gain of 110 in the focus position was observed along with a total flux in the spot of 4x10¹⁰ X-rays/s (conditions: 5.3 GeV, 182 mA, 1.5% bandwidth multilayer, 12 keV X-rays). A measurement of the far field focus ring diameter yielded a divergence of 3.8 mrad, in good agreement with the 4 mrad design of the optic for protein crystallography. Using a small 25 μm square beam, we measured the local reflectivity to be greater than 95% and the inner slope errors of the capillary to average about ±150 μrad, both from raw and elliptically shaped tubing. Our conclusion is that more perfect starting tubing (i.e. one with lower slope errors) is needed to make even more perfect elliptically figured optics in the future

[en] A method is described for observing and recording in real-time x-ray diffraction from an unoriented hydrated membrane lipid, dipalmitoylphosphatidylcholine (DPPC), through its thermotropic gel/liquid crystal phase transition. Synchrotron radiation from the Cornell High Energy Synchrotron Source (Ithaca, New York) was used as an x-ray source of extremely high brilliance and the dynamic display of the diffraction image was effected using a three-stage image intensifier tube coupled to an external fluorescent screen. The image on the output phosphor was sufficiently intense to be recorded cinematographically and to be displayed on a television monitor using a vidicon camera at 30 frames x s^-1. These measurements set an upper limit of 2 s on the DPPC gel → liquid crystal phase transition and indicate that the transition is a two-state process. The real-time method couples the power of x-ray diffraction as a structural probe with the ability to follow kinetics of structural changes. The method does not require an exogenous probe, is relatively nonperturbing, and can be used with membranes in a variety of physical states and with unstable samples. The method has the additional advantage over its static measurement counterpart in that it is more likely to detect transiently stable intermediates if present

[en] The high-brilliance, insertion-device-based, photon beams of the next generation of synchrotron sources will deliver large thermal loads (1 kW to 10 kW) to the first optical elements. Considering the problems that present synchrotron users are experiencing with beams from recently installed insertion devices, new and improved methods of cooling these first optical elements, particularly when they are diffraction crystals, are clearly needed. A series of finite element calculations were performed to test the efficiency of new cooling geometries and new cooling fluids. The best results were obtained with liquid Ga metal flowing in channels just below the surface of the crystal. Ga was selected because of its good thermal conductivity and thermal capacity, low melting point, high boiling point, low kinetic viscosity, and very low vapor pressure. Its very low vapor pressure, even at elevated temperatures, makes it especially attractive in uhv conditions. A series of experiments were conducted at CHESS in February of 1988 that compared liquid gallium cooled silicon diffraction crystals with water cooled crystals. 2 refs., 16 figs., 1 tab

[en] Real-time back-reflection Laue patterns have been made possible through the construction of a specially designed multiwire proportional chamber. This ability to view Laue patterns in live time on an x-y display scope has greatly reduced the magnitude of effort involved in orienting single crystals and of characterizing the nature of less than perfect crystals. (Auth.)

[en] Layered Synthetic Microstructures (LSMs) show great promise as focusing, high-throughput, hard x-ray monochromators. Experimental reflectivity vs. energy curves have been obtained on carbon-tungsten and carbon-molybdenum LSMs of up to 260 layers in thickness. Reflectivities for three flat LSMs with different bandpasses were 70% with δE/E = 5.4%, 66% with δE/E = 1.4%, and 19% with δE/E = 0.6%. A new generation of variable bandwidth optics using two successive LSMs is proposed. The first element will be an LSM deposited on a substrate that can be water cooled as it intercepts direct radiation from a storage ring. It can be bent for vertical focusing. The bandpass can be adjusted by choosing interchangeable first elements from an assortment of LSM's with different bandpasses (for example, δE/E = 0.005, 0.01, 0.02, 0.05, 0.1). The second LSM will consist of a multilayered structure with a 10% bandpass built onto a flexible substrate that can be bent for sagittal focusing. The result will be double focusing optics with an adjustable energy bandpass that are tunable from 5 to 30 keV

[en] Transmission X-ray mirrors have been made from 400 A to 10 000 A thick soap films and have been shown to have novel properties. Using grazing angles of incidence, low energy X-rays were reflected from the front surface while more energetic X-rays were transmitted through the mirror largely unattenuated. A wide bandpass monochromator was made from a silicon carbide mirror followed by a soap film transmission mirror and operated in the white beam at the cornell High Energy Synchrotron Source (CHESS). Bandpasses of ΔE/E=12% to 18% were achieved at 13 keV with peak efficiencies estimated to be between 55% and 75%, respectively. Several wide angle scattering photographs of stretched polyethylene and a phospholipid were obtained in 10 s using an 18% bandpass. (orig.)

[en] A highly polished platinum coated mirror was demontrated to reflect X-rays with high efficiency up to 38 keV (0.33 A). For the mirror operating at an angle of incidence of 8 mrad, the mirror reflected 8 keV X-rays with a 70% efficiency while the reflectivity at 16 keV was only 0.6%. The measured reflectivity of the mirror fell off in energy about 30 times faster than predicted by simple Fresnel theory assuming a smooth surface. This implies, for instance, that the harmonic rejection performance of platinum coated X-ray mirrors at synchrotron radiation sources may be significantly better than expected. In other measurements, very imperfect surfaces of unpolished sheet aluminum, copper and stainless steel surprisingly reflected as much as 30-50% of the X-rays incident upon them at small glancing angles. (orig.)