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Technical Description

Key points

  • Energy range 20 < E < 500 KeV
  • Beam sizes from 0.3 µm to 8 mm

Overall layout

The ID15 straight section houses a complex of beam lines, with two canted branches. This web site 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 is described elsewhere. The overall layout is shown below:

 

X-ray source

Upon resuming user opertion in 2020, ID15A will house two new insertion devices. One is a compact wiggler source W76, which provides a continuous spectrum up to several hundred keV for materials engineering applications in EH2. The spectrum of this device, compared to that of the former wiggler source, is shown below.

The primary insertion device will be 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.

X-ray optics

For EH2, it is envisioned that the white beam will be shaped by high heat load slits, with a maximum beam size of 8 x 6 mm2. Provision has been made for mounting a high-energy monochoromator (in air) at the entrance to the hutch. This can be equipped with Ge crystals for exotic high-energy monochromatic scattering experiments.

For EH3, two monochromators are available. The first is a double multilayer mirror (DMLM) at 40 m from the source in OH1. This provides very high flux at the expense of a band pass of around 0.37 %, and is particularly useful in the lower engery range of the beamline. The second monochromator is a liquid nitrogen cooled double Laue Si monochromator (LLM) mounted in OH2. This provides excellent flux and tunability over the range 40 - 140 keV. The band pass may be tuned from 0.01 to 0.5 % by bending the crystals.

Several options for X-ray focussing are available for monchromatic beams. Transfocators, which consist of motorized cartridges of X-ray refractive lenses are employed. To make the best use of the anisotropic X-ray source, vertical and horizontal focusing are carried out using 1D Aluminium and Berylium lenses at 32 and 53 m respectively. The beam size in EH3 can be tuned down to around 10 µm using these white beam transfocators.

Additional focusing to beam sizes down to 0.3 µm is available using further refractive lenses placed at the entrance to EH3 or a KB-mirror system. The optical layout of the beamline is shown below.

The available optical schemes (in EH3) are listed in the following table.

 

Pre-Upgrade

EBS (if changed) 

Photon Source Parameters (50 keV)

 

 

   RMS beam size (σ)

4.4×49.6 µm2 (V×H)

4.4×27.8 µm2 (V×X)

   Divergence (θ)

4.5×105.5 µrad2 (V×H)

4.4×6.8 µrad2 (V×H)

Source 1

U22 undulator

CPMU18 undulator

   Length

2 m

1.5 m

   Period

22 mm

18 mm

   Maximum deflection parameter (K)

1.788

1.9

   Total Power (6 mm gap)

 6.9 kW

7.4 kW

Source 2

 

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 mm

 

   Thickness (Cu)

0.8 – 25.8 mm

0.0 – 5.1 mm

Vertical focusing transfocator (TF1)

 

 

   Distance from source

32 m

 

   Distance from sample

33 m

 

   Lenses apex radius

100 mm

 

   Lenses vertical geometrical aperture

650 mm

 

   Focused vertical FWHM at sample

15 mm

15 mm

Double multilayer monochromator (DMLM)

 

 

   Materials

[Ni93V7/B4C]500

 

   d-spacing

1.996 nm

 

   Band pass (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)

 

   Maximum flux density at sample (30 keV) (unfocused beam)

4.2×1013 ph/s/mm2

~8.5×1014 ph/s/mm2

Laue-Laue monochromator (LLM)

 

 

   Lattice

Si (111) or Si (311)

 

   d-spacing (111)

3.1347 Å

1

 

 

   d-spacing (311)

1.6370 Å

1

 

 

   Bending radius

30 – ∞ m

 

   Band pass (ΔE/E)

0.01 – 1 %

 

   Cooling

liquid N2

 

   Energy range (111)

40 – 180 keV

 

   Energy range (311)

80 – 250 keV

 

   Acceptance

2.0 mm (V) and 2.0 mm (H)

 

   Maximum unfocused beam at sample

1.26.4 mm2 (VH)

 

   Maximum flux density at sample (70 keV) (unfocused beam)

4×1012 ph/s/mm2

~1.3×1014 ph/s/mm2

Horizontal focusing transfocator (TF2)

 

 

   Distance from source

53 m

 

   Distance from sample

12 m

 

   Lenses radius

100 mm

 

   Lenses horizontal geometrical aperture

650 mm

 

   Focused vertical FWHM at sample 

35 mm

18 mm

Microfocusing CRLs

 

 

   Distance from source

61 – 64 m

 

   Distance from sample

1 – 4 m

 

 

   Lenses radius

100 mm

 

   Lenses horizontal geometrical aperture

650 mm

 

   Vertical beam size at sample

0.5 – 2 mm

0.5 – 2 mm

   Horizontal beam size at sample

3 – 9 mm

1.5 – 5 mm

Kirkpatrick-Baez focusing mirrors

 

 

   Distance from source

64.38 m (V) and 64.65 m (H) (H)

 

   Distance from sample

0.62 m (V) and 0.35 m (H)

 

   Energy range

20 – 69 keV

 

   Output flux at 50 keV with DMLM

1.5×1012 ph/s

4.5×1013 ph/s

   Acceptance

0.3 mm (V) and 0.3 mm (H)

 

   Beam size at sample

0.30.6 mm2 (VH)

0.30.3 mm2 (VH)