Layout

NCD-SWEET beamline optical layout with the main components. Below, a more detailed information is provided.

The chosen optical layout is aimed at delivering high-photon flux onto the sample: A channel cut Si (111) monochromator is used to obtain the monochromatic X-ray beam with a ∆E/E of 2.7·10^-4 at 10.0 keV. Then, the X-ray beam is collimated with an array of 3, 6, or 9 Be lenses. A set of microfocussing Be lenses is also available to focus the X-ray beam on the sample position, obtaining a beam size of 4 × 10 µm² (V × H) at 12.4 keV. Along the beamline, several 4 sets of slits vertical and horizontal slits are used to define and clean the X-ray beam. Before the sample, an in vacuo fast shutter is placed that only opens if data acquisition is demanded, minimizing the sample irradiation unless needed.

Centre of ID U21	0 m
Trigger unit separating Optics hutch and Front End	17 m
Channel cut monochromator Si (111)	22 m
Collimating Be lenses	24.3 m
Microfocussing Be lenses	32 m
Sample position	32.5 m
SAXS Sample-Detector distance	2.1 m up to 7.2 m

Source: In-vacuum undulator (IVU21)

The NCD-SWEET beamline is tunable over a wavelength range of 0.62Å - 1.90Å and delivers a high-photon flux onto the sample, the beam has an excellent beam collimation and photon density, and is also highly stable. For this purpose the photon source of this beamline is an undulator, IVU21, placed in a medium 4 m straight section.

Here some parameters of the IVU21 are presented:

Material	Sm₅Co₁₇ Pure Permanent Magnet
Period	21.6 mm
Number of periods	92
K at minimum gap	1.6
Photon source size (FWHM)	309 x 18 µm² (H x V)
Photon source divergence (FWHM)	112 x 28-22 µrad² (H x V)