Advanced Photon Source

A U.S. Department of Energy, Office of Science,
Office of Basic Energy Sciences national synchrotron x-ray research facility

 

Partner User Proposal Abstract

High-energy X-ray Optics Development (50-100 keV) at the XOR 1-ID Beamline at the APS (PUP-9)

This partner user proposal (PUP) aims to conduct x-ray optics development at the XOR 1-ID beamline of the APS, with a predominant emphasis on high-energy x-ray (50-100 keV) optics. By virtue of its high electron beam energy (7 GeV) and small source size, the APS is a brilliant source of high-energy x-rays that is unique in the U.S., even though its main insertion devices (i.e., APS undulators A) were primarily optimized for the conventional lower photon energies. High-energy synchrotron x-rays have been clearly demonstrated to be the scattering tool of choice for many systems in condensed matter and materials research due to their properties which include long penetration lengths, near elimination of multiple scattering and absorption corrections, small scattering angles, and the accessibility of very high momentum transfers.

Over the last few years the XOR 1-ID beamline has evolved to support primarily high-energy x-ray scattering experiments such as stress/texture determination, pair-distribution function measurements, powder diffraction, fluorescence spectroscopy, small-angle scattering, and diffuse scattering. Consequently, the 1-ID staff was motivated to develop optics specially designed to monochromatize high-energy x-rays efficiently. Instead of a standard-style monochromator, this effort resulted in a cryogenically-cooled monochromator composed of two bent Laue crystals that delivers over ten times more flux than do flat Bragg crystals, with the same output monochromatic energy width. This system, now in routine operation, provides a beam that is fully tunable, has fixed offset, and preserves source brilliance.

This PUP's main program is to continue the tradition of ''doing high-energy optics right,'' by further developing optics dedicated and optimized for the manipulation of high-energy x-rays, which deserve their own methods. This includes not only enhancing the capabilities of the current optics at 1-ID, but developing and testing new high-energy optics concepts as well. The target of the projects is not optics for its own sake, but will be to benefit all the ongoing research conducted the beamline, open additional high-energy-exploiting techniques at 1-ID, and also be of value in guiding future high-energy beamline planning and construction elsewhere at the APS (specifically the proposed HEX-CAT sector) or at other facilities.

To pursue the specific projects in mind and achieve a satisfactory pace of results, 10% of the total beam time at the 1-ID beamline was requested over 3 years. These projects are outlined as follows (order not necessarily reflecting priority):