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Technical Description
Layout
The ID15 straight section houses two canted branches. This page is dedicated to the ID15A branch, which houses the materials chemistry (EH3) and materials engineering (EH2) facilities. The ID15B branch houses a high pressure beam line (EH1), which operates independently of ID15A and has its own webpage. The overall layout is shown here:
X-ray source
The primary insertion device is a CPMU18 undulator, which provides brilliant x-rays in the range 20 -140 keV for materials chemistry applications in EH3. A comparison of the performance of the ID15A sources before and after the upgrade is shown below, illustrating the significant flux increase, particularly at high energy.
ID15A also houses a compact wiggler source (W76), which provides a continuous spectrum up to several hundred keV for materials engineering applications.
X-ray optics
Two monochromators are available. The first is a double multilayer mirror (DMLM) at 40 m from the source in OH1. The DMLM provides very high flux at the expense of a band pass of around 0.37%, and is particularly useful in the lower-energy range of the beamline. The second monochromator is a liquid nitrogen-cooled double-Laue Si monochromator (LLM) mounted in OH2. The LLM provides excellent flux and tunability over the range 40 - 140 keV. The band pass may be tuned from 0.01 to 0.5% by adjusting the bending of the crystals.
Several options for X-ray focusing are available for monochromatic beams. Transfocators, which consist of motorized cartridges of X-ray refractive lenses, achieve independent vertical and horizontal focusing using 1D Aluminium and Beryllium lenses placed at 32 and 53 m from sample, respectively. With transfocators, the beam size in EH3 can be tuned down to around 15 µm. Focusing to beam sizes down to 0.3 µm is possible using either refractive lenses placed at 1-4 m from sample or a KB-mirror system at 0.35-0.62 m from sample. The optical layout of the beamline is shown below.
Photon Source Parameters (50 keV) |
|
RMS beam size (σ) | 4.4×27.8 µm2 (V×H) |
Divergence (θ) | 4.4×6.8 µrad2 (V×H) |
CPMU18 undulator |
|
Length | 1.5 m |
Period | 18 mm |
Maximum deflection parameter (K) | 1.9 |
Total power at 6 mm gap | 7.4 kW |
W76 Wiggler |
|
Length | 0.31 m |
Period | 76 mm |
Maximum deflection parameter (K) | 13.2 |
Total power | 4.6 kW |
Argon gas filter |
|
Length | 1 m |
Pressure | 350 mbar |
Metal coated diamond filters |
|
Thickness (diamond) | 300 µm |
Thickness (Cu) | 0.0 - 5.1 µm |
Vertically focusing transfocator (TF1) |
|
Distance from source | 32 m |
Distance from sample | 33 m |
Lenses apex radius | 100 µm |
Lenses vertical geometrical aperture | 650 µm |
Focused vertical beam FWHM at sample | 15 µm |
Double MultiLayer Monochromator (DMLM) |
|
Material | [Ni93V7/B4C]500 |
d-spacing | 1.996 nm |
Bandpass (ΔE/E) | 0.37% |
Cooling | water |
Energy range | 20-70 keV |
Acceptance (20 keV) | 4 mm (V) and 4.5 mm (H) |
Acceptance (95 keV) | 4 mm (V) and 1.0 mm (H) |
Flux density at sample (30 keV) (unfocused beam) | 8.5×1014 ph/s/mm2 |
Laue-Laue Monochromator (LLM) |
|
Lattice | Si (111) or Si (311) |
d-spacing (111) | 3.1347 Å |
d-spacing (311) | 1.6370 Å |
Bending radius | 30 m - ∞ |
Bandpass (ΔE/E) | 1 - 0.01% |
Cooling | liquid nitrogen |
Energy range (111) | 40 - 140 keV |
Energy range (311) | 80 - 280 keV |
Acceptance | 2.0 mm (V) and 2.0 mm (H) |
Maximum unfocused beam size at sample | 1.2×6.4 mm2 (V⨯H) |
Flux density at sample (70 keV) (unfocused beam) | 1.3×1014 ph/s/mm2 |
Horizontally focusing transfocator (TF2) |
|
Distance from source | 53 m |
Distance from sample | 12 m |
Lenses apex radius | 100 µm |
Lenses vertical geometrical aperture | 650 µm |
Focused vertical beam FWHM at sample | 18 µm |
Microfocusing circular lenses |
|
Distance from source | 61 - 64 m |
Distance from sample | 4 - 1 m |
Lenses radius | 100 µm |
Lenses geometrical aperture | 650 µm |
Focused vertical beam FWHM at sample | 0.5 - 2 µm |
Focused horizontal beam FWHM at sample | 1.5 - 5 µm |
Kirkpatrick-Baez focusing mirrors (KB) |
|
Distance from source | 64.38 m (V) and 64.65 m (H) |
Distance from sample | 0.62 m (V) and 0.35 m (H) |
Energy range | 20 - 100 keV |
Output flux at 50 keV with DMLM | 4.5×1013 ph/s |
Acceptance | 0.3 mm (V) and 0.3 mm (H) |
Beam FWHM at sample | 0.3 × 0.45 µm2 (V⨯H) |