[en] We report on the initial characterization of an elliptically polarized wiggler built by a collaboration between the Advanced Photon Source, the Institute of Nuclear Physics, and the National Synchrotron Light Source. The wiggler has recently been installed in the X13 straight section of the NSLS X-Ray ring. The device consists of a vertical permanent-magnet wiggler and a horizontal electromagnet wiggler. The electromagnets allow the wiggler to produce on-axis circularly polarized soft x-rays with the capability of AC modulation of the polarization. The maximum switching frequency that can be reached is 100 Hz. The degree of circular polarization of the radiation from the wiggler was characterized by making magnetic circular dichroism measurements using the X13A soft x-ray beamline. For a vertical deflection parameter, K_x, of 1.6, the dichroism effects at the Fe L_2,3 edges indicate a degree of circular polarization of approximately 75% using an aperture with a vertical acceptance of 87 μrad. Because both the left- and right-circularly polarized photons traverse identical paths through the beamline optical system, significantly smaller intensity fluctuations associated with switching of the polarization were observed that are typically possible at bending magnet beamlines. This, together with the relatively fast modulation rate, means that it will now be feasible to perform a variety of experiments that have not been possible using bending magnet sources

[en] Construction of the high-resolution soft x ray spectroscopy undulator beamline, 2ID-C, at the Advanced Photon Source (APS) has been completed. The beamline, one of two soft x ray beamlines at the APS, will cover the photon energy range from 500 to 3,000 eV, with a maximum resolving power between 7,000 and 14,000. The optical design is based on a spherical grating monochromator (SGM) giving both high resolution and high flux throughput. Photon flux is calculated to be approximately 10¹²--10¹³ photons per second with a beam size of approximately 1 x 1 mm² at the sample

[en] The x-ray radiation shielding requirements beyond the first optics enclosure have been considered for the beam transport of the 2-ID-B and 2-ID-C branch lines of Sector 2 (SRI-CAT) of the APS. The first three optical components (mirrors) of the 2-ID-B branch are contained within the shielded first optics enclosure. Calculations indicate that scattering of the primary synchrotron beam by beamline components outside the enclosure, such as apertures and monochromators, or by gas particles in case of vacuum failure is within safe limits for this branch. A standard 2.5-inch-diameter stainless steel pipe with 1/16-inch-thick walls provides adequate shielding to reduce the radiation dose equivalent rate to human tissue to below the maximum permissible limit of 0.25 mrem/hr. The 2-ID-C branch requires, between the first optics enclosure where only two mirrors are used and the housing for the third mirror, additional lead shielding (0.75 mm) and a minimum approach distance of 2.6 cm. A direct beam stop consisting of at least 4.5 mm of lead is also required immediately downstream of the third mirror for 2-ID-C. Finally, to stop the direct beam from escaping the experimental station, a beam stop consisting of at least 4-mm or 2.5-mm steel is required for the 2-ID-B or 2-ID-C branches, respectively. This final requirement can be met by the vacuum chambers used to house the experiments for both branch lines

[en] A novel kinematic mount system for a vertical focusing mirror of the soft x-ray spectroscopy beamline at the Advanced Photon Source is described. The system contains three points in a horizontal plane. Each point consists of two horizontal linear precision stages, a spherical ball bearing, and a vertical precision stage. The horizontal linear stages are aligned orthogonally and are conjoined by a spherical ball bearing, supported by the vertical linear stage at each point. The position of each confined horizontal stage is controlled by a motorized micrometer head by spring-loading the flat tip of the micrometer head onto a tooling ball fixing on the carriage of the stage. A virtual sine arm is formed by tilting the upstream horizontal stage down and the two downstream horizontal stages up by a small angle. The fine pitch motion is achieved by adjusting the upstream stage. This supporting structure is extremely steady due to a relatively large span across the supporting points and yields extremely high resolution on the pitch motion. With a one degree tilt and a microstepping motor, the authors achieved a 0.4 nanoradian resolution on the mirror pitch motion

[en] The advantages of using a mirror as the first optical component for an APS undulator beamline for thermal management, radiation shielding mitigation, and harmonic rejection are presented

[en] This document is concerned with the general requirements for radiation shielding common to most Advanced Photon Source (APS) users. These include shielding specifications for hutches, transport, stops, and shutters for both white and monochromatic beams. For brevity, only the results of calculations are given in most cases. So-called open-quotes special situationsclose quotes are not covered. These include beamlines with white beam mirrors for low-pass energy filters (open-quotes pink beamsclose quotes), extremely wide band-pass monochromators (multilayers), or novel insertion devices. These topics are dependent on beamline layout and, as such, are not easily generalized. Also, many examples are given for open-quotes typicalclose quotes hutches or other beamline components. If a user has components that differ greatly from those described, particular care should be taken in following these guidelines. Users with questions on specific special situations should address them to the APS User Technical Interface. Also, this document does not cover specifics on hutch, transport, shutter, and stop designs. Issues such as how to join hutch panels, floor-wall interfaces, cable feed-throughs, and how to integrate shielding into transport are covered in the APS Beamline Standard Components Handbook. It is a open-quotes living documentclose quotes and as such reflects the improvements in component design that are ongoing. This document has the following content. First, the design criteria will be given. This includes descriptions of some of the pertinent DOE regulations and policies, as well as brief discussions of abnormal situations, interlocks, local shielding, and storage ring parameters. Then, the various sources of radiation on the experimental floor are discussed, and the methods used to calculate the shielding are explained (along with some sample calculations). Finally, the shielding recommendations for different situations are given and discussed

[en] Interest in the 0.5 to 3 keV, intermediate x-ray, energy region has recently intensified as this spectral region covers, among others, the important L and M edges of transition-metal and rare-earth magnetic materials, respectively. Third-generation synchrotron facilities with their inherent high brightness have the unique potential to cover this energy region with high-resolution, high-flux x-ray beams ideal for spectroscopic studies. A 5.5-cm-period, planar undulator to be installed on the 7-GeV Advanced Photon Source will produce a high brightness source of intermediate-energy x rays. The 0.5- to 3-keV spectroscopy beamline is based on the spherical grating monochromator design that has already been shown to yield high resolution and throughput in the soft-x-ray region, below 1 keV. The beamline has been designed to cover the entire region with a peak resolving power of 6000--10 000. Photon flux at the sample is calculated to be in the range from 10¹¹ to 10¹³ photons/s into a spot size of 1 mm². A refocusing mirror will be used to further demagnify the image size at a second experimental station. As a second phase to the spectroscopy program, an elliptically polarized insertion device will be used. The polarization preserving nature of the grazing incidence optical elements in the SGM is crucial to obtain x rays of well-defined polarization. The beamline layout, together with calculations of resolution, throughput, power loading, and high harmonic suppression, will be presented. The photoemission experimental end stations for the spectroscopy station will also be briefly described. copyright 1995 American Institute of Physics

[en] We are constructing a soft x-ray intensity interferometer and an undulator based beamline to demonstrate intensity interferometry in the x-ray region. The 10-period soft x-ray undulator at the NSLS provides the necessary coherent flux; the X13A beamline is designed to preserve the spatial coherence of the bright x-ray beam and provide sufficient temporal coherence using a horizontally deflecting spherical grating monochromator. Using the interferometer, which consists of an array of small slits, a wedge-shaped beamsplitter and two fast microchannel plate detectors, we expect to measure the spatial coherence of the undulator beam and therefore the size of the source in the vertical plane. Details of the bean-dine design and the interferometer experiment are discussed

[en] We describe an angle-resolving photoelectron spectrometer for atoms and molecules which uses the magic angle geometry in combination with multidetection such that cross sections and asymmetry parameters can be determined simultaneously. The instrument is based on the cylindrical mirror analyzer (CMA) design with the cylinder axis and the light beam collinear. Only the photoelectrons which are emitted in the ''reverse'' direction at the magic angle reach the ring-shaped position-sensitive detector. The complete system also incorporates a conical effusive gas source, in order to maintain cylindrical symmetry, and very efficient differential pumping between target and electron spectrometer. Results from the C 1s photoionization of CO₂ demonstrate the kind of precision attainable

[en] The advantages of using a mirror as the first optical component for an Advanced Photon Source (APS) undulator beamline for thermal management, radiation shielding mitigation, and harmonic rejection are presented. copyright 1996 American Institute of Physics