X-Ray Beam Modes and Properties
The Insertion Device (ID) for the DCS is a Revolver Undulator that can be switched between two sets of magnets with periods of 23 mm or 14 mm (U23 and U14) to provide spectral tuning in energy from 7 to 70+ keV.
The beamline optics are designed to deliver both unfocused (White) and focused (Pink) x-ray beam modes that can be fine-tuned in energy, beam-size, bandwidth, and flux to deliver an appropriately conditioned beam for each experiment. The three standard beam modes used at DCS are as follows:
- ‘White beam’ refers to the broad-band x-rays directly from the undulator, unfocused and containing all harmonics. The white beam from the U14 is typically used for phase contrast imaging (PCI).
- ‘Pink beam’ is focused by reflecting from dynamically-figured Kirkpatrick-Baez mirrors. The mirrors act as an energy filter on the undulator output, leaving only the lowest energy harmonics. The broad bandwidth (3.5-5.5% BW) beam can be used for x-ray diffraction (XRD), small-angle x-ray scattering (SAXS), or extended x-ray absorption fine structure (EXAFS). Additionally, a very broad pink beam for Laue diffraction can be generated by tapering the magnet gap in the U23.
- ‘Mono’ – The single multilayer monochromator (SMM) in each station can be used for XRD experiments with nearly the same peak spectral flux and narrower bandwidth (1.5% BW).
APS Storage Ring Modes
| Bunch Mode | X-Ray Spacing | Bunch Current (200mA Total) | Weeks per Run |
| 48 | 76.7 ns | 4.17 mA | TBD |
| 216 | 17.04 ns | 0.93 mA | TBD |
Common Experimental Configurations
| Experiment | Energy (keV) | Vertical White Beam Slit (mm) | SMM | FWHM (%) | Calculated Pink Spectral Power (W/eV) | Undulator |
| PCI | 24-26 | 1.0 | N | 5.5 | 0.049-0.015 | U14 |
| XRD | 22 | 1.0 | Y | 1.5 | 0.045 | U14 |
| XRD | 36-71 | 1.0 | Y | 1.5 | 0.012 | U23 |
| SAXS | 24 | 0.5 | N | 3.5 | 0.047 | U14 |
| EXAFS | 9-13 | 1.0 | N | N/A | 0.11-0.065 | U23 |
| Laue Diffraction | Broadband | 1.0 | N | Broadband | N/A | Tapered U23 |
Experimental Capability with APS Beam Modes
| Experiment Type | Compatible Bunch Mode |
| Plate Impact | 48 |
| Laser Drive | 48 |
| Special Purpose | Experiment Dependent |
| Ambient Conditions | Any, but 324 preferred |
PCI Field of View Options
| Experiment Type | Compatible Bunch Mode |
| Plate Impact | 48 |
| Laser Drive | 48 |
| Special Purpose | Experiment Dependent |
| Ambient Conditions | Any, but 324 preferred |
Available X-ray Beam Spot Sizes
| Beam Types | Energy Range | Enclosure | Spot Size |
| White Beam | 7-70+keV | Special Purpose (B-Station) Laser-Shock (C-Station) Impact Facility (D-Station) Impact Facility (E-Station) | 1.4(V) x 2.1(H) mm2 1.8(V) x 2.7(H) mm2 2.2(V) x 3.3(H) mm2 2.5(V) x 3.7(H) mm2 |
| Pink Beam | 7-70+keV | Special Purpose (B-Station) Laser-Shock (C-Station) Impact Facility (D-Station) Impact Facility (E-Station) | Min: 9.9(V) x 8.0(H) µm2 Min: 18.6(V) x 3.4(H) µm2 Min: 40(V) x 30(H) µm2 Min: 52(V) x 37(H) µm2 |
X-Ray Characterization
Complete set of x-ray diagnostics in each station for precise alignment, focus, and characterization of x-rays for each experimental setup
- Laser aligned to x-rays beams provides visible beam path for initial alignment
- GigE camera coupled to YAG crystal with microscope objective for precisely focusing and shaping x-ray beam
- Spectral flux characterization using Si(220) monochromator on precision rotation stage
