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We have measured the magnetic Compton profile (MCP) of ordered and disordered Fe 3Pt samples both above and below their Curie temperature. From these measurements, we have determined the average moment per atom at room temperature to be 2.81μB ± 0.04μB for disordered Fe3Pt and 1.78μB ± 0.05μB for ordered Fe3Pt. At temperatures above Tc, we measured a substantial reduction in the moment (0.6μB ± 0.10μB for disordered Fe3Pt and 0.64μB ± 0.13μB ± for ordered Fe3Pt) and a change in the shape of the MCP. This suggests that the mechanism behind the Invar effect in Fe3Pt can be described by a high-spin to low-spin magnetic phase transition. The experimental MCPs for both ordered and disordered Fe3 Pt are analyzed within the framework of the Weiss 2γ model.

The inclined double crystal monochromator arrangement is very effective in handling high heat loads and holds considerable promise as a monochromator for undulator beams at third generation synchrotrons. Results for the ideal inclined crystal case have been obtained by dynamical diffraction calculations, and diffraction results for the (111) reflection of silicon are presented for an inclination angle of 85{degree}0 and energies of 5 key and 13.84 key. The diffraction characteristics resemble closely diffraction from-asymmetric (111) plane of silicon. However, the inclined and noninclined cases are not identical. Diffraction in the inclined case is slightly different due to refraction. The full width at half maximum of the Darwin-Prins reflectivity curve is slightly increased ({approximately}l%), and the angles of the outgoing beam after one reflection are slightly altered. That is, except for a wave incident at the Laue point in reciprocal space, the diffraction is always slightly asymmetric. The effect can be exactly reversed by an identical second crystal in the (+,{minus}) arrangement.

The inclined double crystal monochromator arrangement is very effective in handling high heat loads and holds considerable promise as a monochromator for undulator beams at third generation synchrotrons. Results for the ideal inclined crystal case have been obtained by dynamical diffraction calculations, and diffraction results for the (111) reflection of silicon are presented for an inclination angle of 85{degrees} and energies of 5 keV and 13.84 keV. The diffraction characteristics resemble closely diffraction from a symmetric (111) plane of silicon. However, the inclined and noninclined cases are not identical. Diffraction in the inclined case is slightly different due to refraction. The full width at half maximum of the Darwin-Prins reflectivity curve is slightly increased ({approximately} 1%), and the angles of the outgoing beam after one reflection are slightly altered. That is, except for a wave incident at the Laue point in reciprocal space, the diffraction is always slightly asymmetric. The effect can be exactly reversed by an identical second crystal in the (+,-) arrangement.

Hard x-ray absorption spectroscopy is combined with scanning microtomography to reconstruct full near edge spectra of an elemental species at each point on an arbitrary virtual section through a sample. These spectra reveal the local concentration of different chemical compounds of the absorbing element inside the sample and give insight into the oxidation state and the local projected free density of states. The method is implemented by combining a quick scanning monochromator and data acquisition system with a scanning microprobe setup based on refractive x-ray lenses. The full XANES spectra reconstructed at each point of the tomographic slice allow one to detect slight variations in concentration of the chemical compounds, such as Cu and Cu(I)2O.

Since high‐energy photons (≳50 keV) are well suited for certain types of x‐ray scattering experiments, we present calculated results for the Advanced Photon Source (APS) Undulator A and APS Wiggler A at high energies. The undulator calculations include the effect of magnetic field errors, which is to smear the high‐order spectral harmonics. At their anticipated initial minimum gap settings, Undulator A should perform better than Wiggler A from the point of view of most high energy experiments up to at least ∼280 keV. A comparison of APS insertion devices to high energy insertion devices in other synchrotron radiation laboratories is also provided.

Three high-energy optics accomplishments are presented. The first is a cryogenically cooled, bent, double-Laue monochromator for 50–200 keV x rays, which delivers over ten times more flux than that from a flat crystal monochromator, but without an increase in energy width. Second, the microfocusing of 50 keV undulator radiation using two stacked Fresnel zone plates is described. Third, a high-resolution inverse-Cauchois scanning analyzer, consisting of a bent Laue crystal, is presented for Compton and fluorescence spectroscopy applications.

A modular filter has been designed for the white‐beam undulator/wiggler beamlines at the Advanced Photon Source. For a typical hard x‐ray application, the filter assembly consists of four filter banks, and each bank has five beam apertures. Therefore a maximum of 625 filter combinations is mechanically possible. To prevent any mistaken setup, which could either damage the filter itself or downstream optical components, a programmable logic controller (PLC) based protection system has been designed. Fuzzy logic was used in this system to limit the memory size and improve the system performance. Ten different storage‐ring beam currents and ten insertion‐device gap setups have been chosen to cover a large dynamic operation range. Aspects of the system fuzzy logic design as well as an example of the calculated results for the control database are presented in this paper.

The first undulator radiation has been extracted from the Advanced Photon Source (APS). The results from the characterization of this radiation are very satisfactory. With the undulator set at a gap of 15.8 mm (K=1.61), harmonics as high as the 17th were observed using a crystal spectrometer. The angular distribution of the third-harmonic radiation was measured, and the source was imaged using a zone plate to determine the particle beam emittance. The horizontal beam emittance was found to be 6.9 {plus_minus} 1.0 nm-rad, and the vertical emittance coupling was found to be less than 3%. The absolute spectral flux was measured over a wide range of photon energies, and it agrees remarkably well with the theoretical calculations based on the measured undulator magnetic field profile and the measured beam emittance. These results indicate that both the emittance of the electron beam and the undulator magnetic field quality exceed the original specifications.