The Advanced Photon Source
a U.S. Department of Energy Office of Science User Facility

Sector 8: Beamline 8-ID

Beamline 8-ID uses the standard APS Undulator A as the insertion device. The design of this undulator beamline is a combination of two established, complimentary designs: that of the Troika Beamline at the European Synchrotron Radiation Facility (ESRF) and that of branchline 2-ID-E at the APS.
Principal features of the 8-ID beamline
  • Transmission Monochromator Side Station:
    A beam-splitting monochromator allows two experiments to run simultaneously using a single undulator beam. It works by horzontally edging a small knife-edge Si crystal into the incident beam and deflecting a portion of this beam into a side-station experiment enclosure. The remaining incident beam is transmitted to the end station.
  • Mirror as First Optical Component in the First-Optics Enclosure (FOE):
    In order to implement the transmission monochromator side station, it is necessary to bring the non-monochromatic undulator beam out of the first optics enclosure (FOE) to the monochromators serving the side and end stations. Using the raw "white" undulator beam outside of the FOE involves design compromises due to the Bremssrahlung shielding required all along the beam line. A solution to this problem is to employ a mirror in the FOE to separate the usable, "pink" x-ray beam from the bremsstrahlung. This solution has the important additional benefit of reducing the heat load on the downstream monochromators.
  • End Station:
    The end station of the undulator beam line is more flexible than the transmission monochromator side station because of the variety of monochromator and focusing options available for the end station. In particular, one can optimize the trade-off between energy resolution and intensity by a choice of Si or Ge crystals, or "pink" undulator beam.
Specifications and info for other Sector 8 beamlines