Polycapillary based μXRF station for 3D colour tomography

Abstract

A : The "Rainbow X-Ray" (RXR) experimental station at XLab Frascati of the Frascati's National Laboratories (LNF) INFN is a dedicated station for X-ray fluorescence studies based on the use of polycapillary lenses in a confocal geometry. The flexible RXR layout allows investigating specimens of the dimensions ranging from several millimeters up to half meter and weighting up to several tens of kilograms. Compared to similar existing XRF stations, apart of the possibility for investigating large samples, the main advantage of this equipment is the detection system with two spectrometers optimized to work separately at high and at low X-ray energies. The confocal geometry combined with a 3-axes fine motion system makes possible 3D µXRF elemental tomographic acquisitions (colour tomography). At present this station in operation at high XRF energies is used for cultural heritage and geological applications. We present and discuss here the analytical performances of this experimental station pointing out the advantages in di erent application areas. K : Computerized Tomography (CT) and Computed Radiography (CR); X-ray fluorescence (XRF) systems 1Corresponding author.

X-ray applications and recent advances @ XLab Frascati

“…Our layout is based on the combination of three X-ray Oxford Apogee tubes (W, Mo and Cu anodes), a set of mechanical components and motors for lens alignment and scanning, and an optical table providing many geometrical setup possibilities. RXR (Rainbow X-Ray) is an optimized system of previous versions (Hampai et al 2008(Hampai et al , 2014(Hampai et al , 2018 dedicated to performing 2D/3D XRF micro-imaging and TXRF (Total Reflection X-ray Fluorescence) analysis. It is equipped with two detectors of different energy efficiency aiming at measuring a full spectrum ranging from 800 eV to 25 keV.…”

“…a The first layer refers to the lower volume of the 3D scan and b the second layer has been obtained by scanning slightly below the top surface of the screw. Images clearly show three different regions: a high fluorescence due to the presence of the metal screw (white area), a region associated with the primary radiation scattered by the glue (grey area) and a signal-free region (black area)(Hampai et al 2018)…”

Molybdenum Oxides Coatings for High Demanding Accelerator Components

“…Actually, since the copper substrate was replaced by the sapphire and due to the very low efficiency of the RXR confocal setup at low energy, we could not apply the same method to evaluate the thickness of the coating. From the Cu fluorescence intensity ratio (i.e., from the I 0 /I ratio of the Moseley law [30], assuming to know the absorption coefficient of MoO 3 ), we can estimate the sample thickness. In the left panel of Figure 5, the integrated Cu fluorescence intensities vs. depth are shown, while in the right panel, the path length obtained by the Moseley equation is shown.…”

“…The flat region in the top right panel corresponds to 1.71 ± 0.45 µm and can be interpreted as the real path that the fluorescence radiation travels from the copper substrate to reach the surface of the film. Since the radiation was not hitting the surface along the normal direction [30], from trigonometrical consideration we can obtain both the path travelled by the fluorescence radiation inside the film (l) and the thickness of the MoO3 film (x = 0.86 ± 0.30 µm).…”

Challenging X-ray Fluorescence Applications for Environmental Studies at XLab Frascati

“…Indeed, the combination of a polycapillary lens with a fine-focus X-ray tube makes it possible to achieve a focusing spot with diameters less than 50 µm. Moreover, it can provide the intensity radiation flux necessary to perform challenging elemental analysis [9]. One of the most attractive applications of such configuration is the confocal geometry with two conjugated X-ray polycapillary lenses [2,9,10].…”