1. Responsible Person
Paul Zschack (630) 252-0860 (voice) (630) 252-0862 (fax) zschack@anl.gov
2. Introduction
The UNICAT mission is to provide advanced x-ray techniques to a diverse scientific community. Station 33-ID-D will function as a multi-purpose scattering facility capable of high resolution scattering with excellent energy resolution. This facility is intended to support advanced materials research as well as condensed matter physics. Primary usage by UNICAT members will encompass structural crystallography, diffuse x-ray scattering, magnetic x-ray scattering, ultra-small-angle x-ray scattering, x-ray microscopy, millivolt and nanovolt resolution spectroscopy, and time-resolved techniques. Station 33-ID-E will provide a specialized UHV surface/interface scattering facility used for the study of reconstruction, relaxation, roughness, melting, chemical reactions, and phase transitions on bulk surfaces, at buried interfaces, and in multilayers. Planned for this station are MBE and CVD growth capabilities to investigate real-time growth behavior.
3. Source Characteristics
APS Type A undulator
4a. Optics Specification for 33-ID-D
Tunability: 4-40 KeV Energy Resolution (DE/E): 10-4 Demagnification: 2.9 Beamsize (v x h): 0.065 x 0.28 mm2
4b. Optics Specification for 33-ID-E
Tunability: 4-40 KeV Energy Resolution (DE/E): 10-4 Demagnification: 1.9 Beamsize (v x h): 0.09 x 0.34 mm2
5. Beamline Description
The UNICAT has selected Undulator A to provide high brilliance x-rays over the energy range 4-40 KeV. A white-beam slit located in a first optics enclosure will select the central cone of undulator radiation. A set of Be filters is available to remove low-order harmonics when necessary to reduce the heat load to the monochromator. To isolate the beamline from the storage ring vacuum, a Be window is included in the second optics enclosure at approximately 43 m from the undulator source. The first active optical element is a high heat load (cryo-cooled) monochromator, located at ~45 m. This monochromator is a double crystal design initially utilizing Si (111) crystals, with the first crystal liquid nitrogen cooled. The second crystal is dynamically bent to provide sagital focus at either end-station, or to horizontally collimate the x-ray beam. This monochromator is UHV compatible, and includes motor and piezo-driven motions to provide variable focus and beam offset. To provide harmonic rejection and vertical focus, UNICAT has chosen a double mirror configuration. Each mirror is designed to provide excellent harmonic rejection, while maintaining high reflectivity. Each has stripes of Pt, Pd, and Si which can be selected to afford the highest throughput for the operating x-ray energy. In addition, the first mirror is dynamically bent to allow vertical collimation or focusing at either experimental end-station. The monochromatic, focused beam is then used in either experimental end-station. Operations time is therefore split between the two experimental enclosures.
6. Detectors
Current detectors include: film, a two dimensional CCD camera, gas-filled proportional counters, gas-filled ion chambers, scintillation detectors, and assorted analyzing crystals.
7. Experimental Equipment
Station 33-ID-D contains a multi-axis Newport goniometer for crystallography and scattering investigations. This instrument is a kappa-geometry design, and provides for convenient in-plane vertical or out-of-plane horizontal scattering measurements. Also available is a Huber 4-circle goniometer which has been modified to accommodate a two-stage helioplex cryostat for low temperature investigations. An optical table is included in the station for beam conditioning optics such as channel-cut crystals or polarizers. This conditioning area also supports USAXS capabilities. Experimental end-station equipment such as cryostats, sample cells, specialized detectors, or USAXS equipment may only be available through special arrangement with the CAT.
Station 33-ID-E is equiped with an UHV chamber that provides routine surface-science capability, and thin-film growth. This facility may only be available through special arrangement with the CAT.
8. Beamline Control & Data Acquisition
Beamline control is provided through a SUN UNIX platform, using the EPICS control system (channel access calls) and distributed VME crates. Diffractometer control and data acquisition is accomplished with the use of SPEC.
9. Beamline Status
Operations began in November, 1999. |
