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

Beamline Overview

4-ID-D optics

Source Properties

SmCo permanent magnet undulator

  • Period: 3.5 cm
  • Length: 2.4 m
  • Gap: min. 10 mm
  • Linear horizontal x-ray polarization
Optical Components
Component Properties
White beam slit Controls the size of the white beam limiting power incident on monochromator; typical size 1x2 mm (VxH)
Monochromator Double crystal monochromator with Si (111)-cut crystals. First crystal is internally cooled (LN2). Covers 2.7 to 40 keV enery range.
Phase retarders

In-vacuum phase retarder tank with collection of C(111) diamond crystals with varying thickness in the 50-500 microns range for polarization control in the 3.2-15 keV range. Can place either a single, or two phase plates in tandem in the beam for switching between LCP and RCP or between L-H and L-V. PZT actuators enable fast polarization switching at approx. 13 Hz. A 10-microns thick Si(111) phase plate is available for LCP-RCP switching in the 2.8-3.2 keV range. 

Toroidal focusing mirror Pd coated toroidal mirror. Focuses the beam in both horizontal and vertical directions at the position of the diffractometer when incidence angle is 3 mrad. Incidence angle up to 5.5 mrad for harmonic rejection at low energies, albeit with degraded focusing.
Plane mirror Redirects beam from the toroidal mirror towards the horizontal plane. Features Pd and Si stripes  used to reject higher x-ray harmonics. Incidence angle up to 5.5. mrad.
Entrance slit Reject any spurious beam coming from the optical hutch; typical size 1x1 mm.
8C incident slit Controls the beam size incident the 8C Huber diffractometer.
Magnetic incident slit Control the beam size iluminating the KB mirror. If the KB mirror is not used, it controls the beam size incident on the 6 T magnet.
Kirkpatrick-Baez mirror Bendable mirrors coated with Rhodium. Focuses the beam into the 6 T magnet. Vertical/horizontal focusing mirror lenght is 10/20 cm, respectively. Can be used in tandem with toroidal mirror to optimize flux (image secondary source). Typical focused beam size in the 10-20 microns range.


Beam Properties

X-ray energy

  • Full accessible range: 2.7 to 40 keV
  • Focused beam: 2.7 to 23 keV (with toroidal mirror at 3 mrad)
  • X-ray polarization control: 2.7 to 15 keV

Beam size

  • At 8C diffractometer
    • Focused: ~100x250 microns (vertical x horizontal)
    • Unfocused: limited by incident slit (full beam ~ 1x2 mm)
  • ​At 6T magnet:
    • ​Focused (with toroidal and KB mirrors): ~15x15 microns
    • Focused (with toroidal): ~150x200 microns (adjusting toroidal mirror bender and incidence angle)
    • Unfocused: limited by magnet incident slit (full beam ~ 1x2 mm)

Photon Flux


Control Software

Beamline 4-ID-D uses the EPICS platform for beamline control.  This is a distributed client-server software where seperate server computers (IOCs) are used to control and monitor different portions of the beamline, and a separate client computer is used for data aquisition and display information. The client computer controls the other IOCs via the local ethernet network.  The EPICS client "MEDM" is used for graphically displaying information about the beamline. The command line driven program SPEC is used for scanning and other data acquisition functions. More information on each of these is found below.

Data Analysis Tools

Scans from SPEC data files can be displayed at the beamline using several different plotting packages

  • pyMCA - ESRF graphical scan display tool
  • Newplot - ESRF graphical scan display tool (depreciated)
  • Cplot - Command line tool distributed with SPEC
  • Xplot - Part of XOP x-ray analysis package (IDL based)
Techniques and Experimental Setups

Magnetic Scattering


  • On and off resonance single crystal magnetic diffraction
  • Magnetic reflectivity


Magnetic Spectroscopy


  • X-ray magnetic circular dichroism (XMCD)
  • X-ray Absorption Near Edge Structure (XANES)
  • X-ray Absorption Fine Structure (XAFS)