Specifications
Beamline Flux
The experimental flux curves for the 2 storage ring operation energies at Elettra (i.e. 2.0 and 2.4 GeV) normalized to the beam current (300 and 160 mA respectively, typical top-up conditions) are shown below. The output flux was characterized immediately downstream of the refocusing mirror, at 14.3 m from the source, by using 2 ionization chambers behind a 0.3mm thick Beryllium window. The output curves are following closely the expected spectral dependence.
Light Source
| Type: Bending Magnet | Ring energy: 2.0 GeV | Ring Energy: 2.4 GeV |
| Critical Energy | 3210 eV | 5590 eV |
| Source Size (nominally) |
sx = 0.33 mm sy = 0.066 mm |
sx = 0.46 mm sy = 0.07 mm |
For more information, please refer to Elettra parameters.
Further details on the optical concept for the X-Ray Fluorescence beam transport system are reported in:
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Optimisation of a compact optical system for the beamtransport at the x-ray fluorescence beamline at Elettra for experiments with small spots;
W. Jark, D. Eichert. L. Luehl, A. Gambitta;
Proceedings of SPIE, Vol. 9207 Advances in X-Ray/EUV Optics and Components IX, pp: 92070G (2014);
doi: 10.1117/12.2063009;
Beamline optical scheme
Collimation mirror
The x-ray beam produced in the bending magnet passes through a set of double slits defining an aperture of about 1.4 x 1.4 mm2.
The divergent beam passing through the slits is then collimated by a Rh-coated, spherical profile mirror. The vertically collimated beam reflected off the collimator proceeds towards the monochromator.
Monochromator
The monochromator was designed internally at Elettra Sincrotrone Trieste by the X-Ray Fluorescence team.
It operates in the energy range 2 - 14 keV with small spectral bandwidth (Si(111), InSb crystals) or in the 0.7 - 14 keV with high flux (multilayers).
| Double Crystals monochromator | ||
| Crystals |
Si (111) InSb |
3.7 - 14 keV 2 - 3.7 keV |
| Multilayers |
High Energy: RuB4C Coating Medium Energy: NiC Coating Low Energy: RuB4C Coating |
4 - 14 keV 1.5 - 8 keV 0.7 - 1.8 keV |
| Resolving Power, see resolving power of the monochromator |
Si (111) InSb, Multilayers |
~ 1 eV @ 7 keV ~ 1 eV @ 2.2 keV ~ 55 eV @ 1 keV ~ 180 eV @ 14 keV |
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The crystals and multilayers are mounted on a support (shown in the picture and scheme above) which is moved according to the energy range needed for each experiment. Moving the support from left to right, one accesses the Si (111), InSb(111), double multilayer for high and medium energies, and low energies multilayer.
Refocusing mirror
The refocusing mirror, placed in close vicinity of the monochromator, is a Rh-coated, toroidal mirror with af bicycle tyre profile. It focuses the beam both vertically and horizontally at the exit slits.
Higher Order Suppressor
While energies above 15 keV are absorbed upon reflection on the Rh-coated mirrors, a higher order harmonics contamination exists in the monochromatised beam up to about 7 keV.
The suppression of such higher order radiation is ensured by an independent optical device named the Higher Order Suppressor (HOS). The HOS is made up of a pair of parallel plane mirrors intercepting the beam in grazing incidence.
The mirror has two sides having different coatings:
A Rhodium coating, for energies between 8 and 14 keV, operated at fixed angle, provides 85% of transmission.
A Carbon coating for photon energies < 8 keV, operated with a variable angle, provides a transmission of about 95% between 3.5 and 8 keV, and of about 50% at 0.7 keV.
Sample holders
Different supports are available to host the samples.
Users willing to bring their sample holders are asked to contact the staff to ensure the compatibility with the sample manipulation system.
1. Hollow holders
These holders are ideal for whenever the X-ray beam might be crossing the whole thickness of the sample. These holders are designed to work at 45° with respect to the X-ray beam direction and have a hole in the middle where the beam can pass through without exciting anything else but the sample.
Two designs are available: in both cases, the overall dimesions are 12 x 2.5 cm2 with the longitudinal hole being 7.1 mm or 10 mm wide.
Several samples can be mounted at once. They can be kept in place using teflon stripes screwed to the main structure, or kapton/carbon tapes.
2. Flat holders
These supports are best suited for Grazing Incidence and Reflectivity measurements, but they can also be used for collecting XRF maps.
They offer a large surface (12 x 5.5 cm2) to accomodate samples which can be mounted using teflon stripes screwed in the main structure.
Sample nature may vary from thin films to artefacts of different shapes.
We have two versions: one in stainless steel and another one in teflon.
3. Glass slide holders
These supports are designed to host sample supports having a circular shape of diameter 26mm.
This choice has proven very efficient for XRF maps collection in the case of thin sections (few μm) of biological samples.
The picture below shows 4 samples of rat organs freeze dried and deposited on an ultralene foil. The ultralene is kept tight and wrinkle-free by two plastic rings.
4. Total reflection holders
These holders can host up to 3 glass reflectors and are dedicated to total reflection measurements.
