Upgraded imaging capabilities at the BAMline (BESSY II)

Abstract

The BAMline at the BESSY II synchrotron X-ray source has enabled research for more than 20 years in widely spread research fields such as materials science, biology, cultural heritage and medicine. As a nondestructive characterization method, synchrotron X-ray imaging, especially tomography, plays a particularly important role in structural characterization. A recent upgrade of key equipment of the BAMline widens its imaging capabilities: shorter scan acquisition times are now possible, in situ and operando studies can now be routinely performed, and different energy spectra can easily be set up. In fact, the upgraded double-multilayer monochromator brings full flexibility by yielding different energy spectra to optimize flux and energy resolution as desired. The upgraded detector (based on an sCMOS camera) also allows exploiting the higher flux with reduced readout times. Furthermore, an installed slip ring allows the sample stage to continuously rotate. The latter feature enables tomographic observation of processes occurring in the time scale of a few seconds.

Keywords: X-ray optics; computed tomography; double-multilayer monochromators; pink beams; synchrotron radiation.

Figure 1

The DMM in three-stripe design; lateral movement of the DMM selects one of the stripes. (a) Pd layer, (b) W/Si multilayer and (c) Mo/B₄C multilayer. These allow different spectral characteristics to be obtained. Calculated example spectra for 20 keV are given in (d)–(f) (the y axis is in a.u.); layer parameters are reported in the table.

Figure 2

Photograph and sketch of the detector setup in white-beam configuration.

Figure 3

JIMA resolution target; enlarged view of 0.8 µm lines; detail and a plot through lines. The circles in the blue insert are normalization artefacts due to beam instabilities.

Figure 4

A slip ring offering eight channels (each with currents of up to 1 A) to facilitate cable management during rotation of the sample stage.

Figure 5

Scan options shown in the example of an Li pouch cell with 7 mm width. (a) 3D view, (b) horizontal slice of a standard scan strategy and reconstruction (see main text), (c) monochromatic beam in step-scan mode; (d) monochromatic beam in on-the-fly scan mode; polychromatic (pink) beam in on-the-fly scan mode acquired for (e) 20 s and (f) 10 s; (g)–(j) enlarged detail of (c)–(f).