Electron micrography and x-ray study of dip-lacquered LiF (220).

It has been proposed to use the 220 reflection of LiF with a multilayer deposited upon the top for simultaneous spectroscopy near Fe-k and O-k and below the C-k absorption edge (284 eV) in x-ray astronomy. We demonstrate that a substantial reduction of surface roughness is obtained by dip lacquering state-of-the-art polished LiF(220) surfaces. Using a microdensitometer analysis of electron micrographs of surface replicas and x-ray reflection, we have measured approximately 10-A rms roughness of Au-coated dip-lacquered LiF(220) crystals, as opposed to approximately 60 A measured on the bare LiF(220) crystal surface.

X-Ray Study of State-of-the-Art Small (d-Spacing W/B4C Multilayers.

Two small d-spacing W/B4C multilayers have been studied at three different x-ray energies CuKα1, AlKα, and FeLα. Measurements of total reflection, specular and mosaic Bragg reflection, and high resolution studies were made at Cu Kα1. Multilayer parameters are deduced from the data and the perfection of the multilayer structure is evaluated by Comparison with model Calculations.

Studies of multilayers and thin-foil x-ray mirrors using a soft x-ray diffractometer.

A versatile x-ray diffractometer is described in detail. Two applications to the study of x-ray optical elements are presented. The first is a Bragg reflection study of state-of-the-art multilayers deposited both on conventional Si-wafer substrates and on superpolished substrates such as fused quartz and electroless nickel. These data are compared to data previously obtained at FeKα. The second study is a reflectivity and scattering study of various thin-foil x-ray reflectors proposed for up-coming x-ray satellite missions. All the data have been obtained at MgKα = 1.2536 keV.

Surface correlation function analysis of high resolution scattering data from mirrored surfaces obtained using a triple-axis x-ray diffractometer.

Within various x-ray programs there exists a need for a detailed investigation of the surface roughness of mirrored surfaces over a wide spatial wavelength bandwidth, ranging from large scale figure error to micro roughness. A number of methods exist to measure the surface roughness. Common to all methods is that they are bandwidth-limited. A crucial point in the analysis of data is, therefore, to specify accurately the wavelength bandwidth limitation and to determine the surface autocorrelation function within this bandwidth. We present a number of scattering measurements obtained using a triple-axis perfect-crystal x-ray diffractometer and the results of an autocorrelation function analysis. Furthermore, we present some measurements of integrated reflectivity, which we believe provide evidence for microroughness in the range from a few angstroms to tens of microns.

Measurements of mosaicity and perfection of crystallites in commercially available crystals using a 4-axis perfect-crystal x-ray diffractometer.

Measurements of mosaicity and the intrinsic scattering from individual crystallites of commercially available crystals are presented. The set of crystals investigated has been proposed to be used as the energy dispersive element in a high resolution Bragg spectrometer for x-ray astronomy. The measurements reveal a high degree of perfection of the crystallites, even in the presence of considerable mosaicity. This is encouraging with relation to an eventual use of the crystals in a high resolution Bragg spectrometer for x-ray astronomy. The measurements were performed using a novel four-crystal x-ray diffractometer. The resolution properties of this diffractometer are discussed in detail and compared with more conventional three-crystal and twocrystal x-ray diffractometers.

Bragg imaging of extended cosmic x-ray sources: the objective crystal spectrometer.

A need exists for a high resolution (E/DeltaE greater, similar 500-1000), imaging (~5 x 5 arcmin pixel) spectrometer capable of studying cosmic x-ray sources with appreciable angular extent (up to 1-2 degrees ) and which emit a broad range of line spectra from highly ionized plasmas (oxygen through iron). A large flat objective crystal couples nicely to a modest resolution but high throughput x-ray concentrating telescope to produce high dispersion images of diffuse x-ray sources in each of the several lines present in the spectrum. Unprecedented spectral resolution is provided for point sources and, provided that they do not vary on rapid time scales, a spectrum can be scanned over a wide energy range with unparalleled sensitivity.

Bragg reflection concentrators for hard x-ray astronomy.

The use of parabolic concentrators with mosaic Bragg crystals as reflectors to the problems of hard x-ray source and cyclotron line detection is discussed. The primary application of the instrument is to detect the broad continuum of hard x-ray sources at energies above ~5 keV where normal grazing incidence concentrators become inefficient. The sensitivity of the instrument is calculated for pyrolytic graphite and lithium fluoride reflectors. Sensitivity for sources with continuum fluxes 10(-3) Crab in the >20-keV energy range is possible for observing times of 10(4) to 10(5) sec.

Spherical crystal imaging spectrometer (SCIS) for cosmic x-ray spectroscopy.

The application of a spherically bent crystal x-ray spectrometer to cosmic x-ray problems is discussed. This is the only geometry whose diffraction properties are preserved under all rotations of the spacecraft. The combination of Bragg reflection and spherical aberration provides for stigmatic imaging of extended sources and minimum spatial and/or spectral resolution loss arising from source extent and spacecraft pointing errors. The sensitivity of the instrument is discussed in the context of a Spacelab mission.

Focusing x-ray spectrograph for laser fusion experiments.

X-ray spectra from laser fusion targets are normally measured with flat crystal (nonfocusing) spectrographs. We describe here the characteristics of a focusing spectrograph which is capable of recording wide band spectra with significantly higher sensitivity. Measuring spectra in the (10-11) A range from glass microballoons imploded by a two-beam Nd:Glass laser system we find intensity per unit area on film about 100 times higher with a curved mica than with a flat mica spectrograph.

Diffraction grating transmission efficiencies for XUV and soft x rays.

Efficiencies for diffraction of 45-275-eV x rays into orders by interferometrically formed, electrodeposited, gold transmission gratings have been measured on the 4 degrees beam line at the Stanford Synchrotron Radiation Project (SSRP). Anomalous dispersion affects the observed efficiency since the gold is partially transmitting to x rays. Model calculations which include anomalous dispersion are in good agreement with observations. With a suitable choice of material and thickness, a grating can be optimized for a given wavelength range by reducing the zero order transmission and enhancing the higher orders. Even orders are suppressed for a grating with equal slit and wire sizes.