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Interest in optics for hard X-ray broad-band application is growing. In this paper, we compare the hard X-ray (20–100 keV) reflectivity obtained with an energy-dispersive reflectometer, of a standard commercial gold thin-film with that of a 600 bilayer W Si X-ray supermirror. The reflectivity of the multilayer is found to agree extraordinarily well with theory (assuming an interface roughness of 4.5 A), while the agreement for the gold film is less. The overall performance of the supermirror is superior to that of gold, extending the band of reflection at least a factor of 2.8 beyond that of the gold. Various other design options are discussed, and we conclude that continued interest in the X-ray supermirror for broad-band hard X-ray applications is warranted.

Nanometer scale structures such as multilayers, gratings and natural crystals are playing an increasing role in spectroscopic applications for X-ray astrophysics. A few examples are briefly described as an introduction to current and planned applications pursued at the Danish Space Research Institute in collaboration with the FOM Institute for Plasma Physics, Nieuwegein, the Max-Planck-Institut fur Extratemestrische Physik, Aussenstelle Berlin, the Space Research Institute, Russian Academy of Sciences, the Smithsonian Astrophysical Observatory, Ovonics Synthetic Materials Company and Lawrence Livermore National Laboratory

The basic design and performance of a novel x-ray scalpel device for interstitial radiosurgery are reported. The x-ray scalpel is comprised of a capillary optics collimator conjugated with a high brilliance microfocus x-ray tube and a thin hollow needle (tip) attached to the collimator. The device is capable of producing a high dose rate (about 140 Gy min(-1) in water-like absorber at the exit window), 0.7 mm diameter, quasi-parallel beam that can be delivered to a targeted site by a minimally invasive procedure. Contrary to insertable x-ray tubes or radionuclides used in brachytherapy and complying with the 1/r(2) radiation attenuation law, the dose rate for a quasi-parallel beam decreases with distance as mu exp(-mu r), where mu is the energy-dependent linear attenuation coefficient in the exposed medium. Moreover, the shape, energy and the dose attenuation curve of the x-ray beam can be adjusted. Two versions of the x-ray scalpel device (5.4 keV and 20.2 keV) are described. We present results from our first test of the x-ray scalpel as a controllable source of focal radiation for producing radiation necrosis in rat brain tissue. Irradiation was transdurally delivered to the rat cerebral cortex for 10 min at a dose rate of 20 Gy min(-1).

The basic concept, design and performance of a novel needle-based x-ray system for medical applications are reported. The main principle of the system is based on a two-stage production of x-rays. The system comprises a conventional x-ray tube with an Ag anode, any known type of conditioning optics and a 2.2 mm diameter hollow needle with an interchangeable Mo target. The target can be moved along the needle axis and rotated around the needle axis. The needle x-ray device allows for adjustment in energy and flux intensity of the x-rays emitted by the target. The depth dependence of the intensity, dose rate as well as spatial and energy distribution of the radiation emitted by the target have been experimentally measured. The depth dose rate results have been compared with theoretical calculations using a Monte Carlo simulation of the x-ray production process. These studies have experimentally confirmed that the concept of this x-ray system is correct. Further improvement of the device can increase the dose rate up to the levels required for clinical applications.

W-B4C multilayers with single d-spacing period of 2.2 nm have been deposited on 330 long by 50 mm wide Si substrates to be used as monochromators for a computed tomography application. Using magnetron sputtering and a substrate masking technique, d-spacing uniformities of +/- 0.86% and +/- 1% were obtained over a 180 mm by 100 mm area for 2.2 nm and 4.2 nm d-spacings respectively. Two separate processes were used to coat the 330 mm long substrate, wherein half of the substrate was coated in each process. A similar process was used to deposit depth graded W-B4C supermirrors on Si and CVD SiC substrates for a beamline pre-mirror application. The 330 mm long by 50 mm wide Si and 300 mm long by 79 mm wide SiC substrates were coated with 20 bi-layer supermirrors with d-spacings ranging from 4.4 nm to 10.8 nm. For an angiography research application laterally graded W-B4C multilayers were deposited on 150 mm by 120 mm silicon substrates. A strong nonlinear d-spacing gradient, from 1.6 nm to 3.8 nm was achieved across the mirror's surface in an attempt to provide uniform intensity over the reflected area. The maximum and minimum d-spacing gradient was 0.06 nm/mm and 0.003 nm/mm, respectively. We measured and mapped the d-spacing gradient using a custom Cu-Ka diffraction system. The measured d-spacings were within +/- 1.5% of the intended d-spacings.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Reflectivity at (lambda) equals 0.154 nm and mechanical stress in the bulk thin films of tungsten and silicon and single d- spacing multilayers on their basis with d approximately equals 2.8 nm deposited by the magnetron sputtering technique on flat thin substrates of Si wafer (approximately 0.2 mm), glass (approximately 0.3 mm), and epoxy gold replicated aluminum foil (approximately 0.3 mm) have been studied. The interfacial roughness of the multilayers has been calculated from the x- ray reflectivity curves as the following: on Si wafer (sigma) approximately equals 0.31 nm, on glass (sigma) approximately equals 0.32 nm, and on foil (sigma) approximately equals 0.34 nm. There was not observed a significant dependence on the stress in the Si film with change in rf power, Ar gas pressure and biasing. For the W films an increase of dc power results in an increase of stress. A similar relationship is also evident for W films deposited by rf power, but this dependence is less pronounced. The influence of low temperature (up to 200 degrees Celsius) annealing on x-ray reflectivity and stress in the multilayers has been investigated. There was not found an appreciable changes in the absolute value of reflectivity or in d-spacing with annealing temperature. The stress in the coatings changes with annealing temperature from compressive to tensile. There was observed a temperature of annealing at which the stress is no longer present in the film. The absolute value of this temperature measured for W/Si multilayer is approximately 120 degrees Celsius.

Traditional high-Z coated X-ray telescopes for the >= 1 keV range all have a loss of throughput with higher energies, owing to the inverse proportionality between the critical angle and energy. We have shown that this can, to some degree, be countered by employing multilayers on the outermost reflectors. A W/B4C multilayer has been fabricated and its 8 keV X-ray reflectivity measured and modeled, yielding an interface-roughness of 3.6 angstroms. This measurement and the resulting model-fit form the basis for computing the performance of `AXAF-S'-sized conical and Kirkpatrick-Baez telescopes. Depending on the specifics of the design, a factor 3 - 5 increased throughput was obtained in a narrow energy band, or a 30 - 100% increase in a wider-band. This throughput ia gained at the expense of the throughput at 2 - 4 keV, which is reduced by 20 - 30%.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The x-ray characterization of multilayer coatings at very low angles on curved substrates is limited by the radius of curvature and surface dimensions. Plane and cylindrical multilayers were manufactured in the same process and characterized as deposited. After flattening the cylindrical surface and curving the plane surface, the same were recharacterized. These measurements and the techniques used to characterize cylindrical surfaces are discussed with the goal of developing techniques for future application to the characterization of spherical, elliptical, or paraboloidal surfaces.

We present a new high-precision and cost-efficient method of manufacturing aspheric crystals and pseudo-crystals. The concept including calculations, limits of precision, and manufacturing details is discussed. The advantages of this method are illustrated by the application and use of a Johansson bent quartz crystal in an x-ray sequential spectrometer. The resolving power of the spectrometer is compared with the Siemens SRS 300 and the Fisons/ARL 8420 by a comparative measurement of uranium ore. The comparison involves the detection of 0.006 Rb (K(alpha) ) present as background. Options for future investigations and applications of this method are discussed.

The loss of throughput observed at higher energies for traditional grazing-incidence x-ray telescopes coated with high-Z elements can be partly countered by employing multilayers on the outermost reflectors. Using 8-keV reflectivity data from a periodic W/B4C multilayer, the expected performance of intermediate-sized telescopes of (1) the nested Kirkpatrick-Baez geometry and (2) the conical approximation to a nested Wolter-I geometry is computed. Depending on the multilayer design, the throughput was increased by a factor of 3 to 5 in a 1.5-keVwide band, or by 30% to 100% in a 3-keV-wide band. This gain is obtained at the expense of a 20% to 30% loss of throughput over the 2- to 4-keV band. These designs lend themselves well to astrophysics missions, such as spectroscopy of the H- and He-like iron emission lines (6.4 to 7.1 keV). The technology for multilayer coating, mounting, and configuring of the flat reflectors required by the Kirkpatrick-Baez telescope exists, so that an Fe-line multilayer telescope could be built today.

WHEN NOVOCAIN or procain is injected subcutaneously in guinea pigs in proper doses, the body temperature is lowered to a considerable degree in one or two hours. Glaubach and Pick (i) have shown that this effect does not occur when thyroxin is administered to the animals for several days prior to the injection of the novocain or procain. This fact seems to suggest a suitable method for studying the possible antagonistic action of certain substances toward thyroxin. Using another method, one of us (J. B.) with his coworkers (2, 3) has demonstrated that such a protective effect against thyroxin can be obtained with lipoid extracts of blood and pancreas. A similar though less marked effect can be obtained with olive oil and with various preparations of blood manufactured and recommended in Germany for the treatment of hyperthyroidism. The protective action, however, has been noted only in animal experiments.