Sil'tronix customer : ESRF

Crystal Analyser Laboratory at the ESRF

The European Synchrotron Radiation Facility (ESRF) in Grenoble has been manufacturing spherical analyser crystals for many years. Spherical analysers are optical devices for X-rays consisting of a thin single-crystal wafer bonded onto a concave spherical Pyrex surface. The wafers are normally made from Si or Ge.

These optical components spherical analysers are key elements for X-ray beamlines at large facilities such as the ESRF and are essential for the implementation of certain types of spectroscopic methods such as X-ray Raman Spectroscopy (XRS), Resonant Inelastic X-ray Scattering (RIXS), Inelastic X-ray Scattering (IXS) and Emission Spectroscopy (ES). In these applications, the analyser crystals permit a very precise measurement of the energies of X-rays which illuminate them.

The ESRF has several such beamlines, each of them using spectrometers requiring multiple analyser crystals to ensure a maximum collection solid angle. The biggest, at the ID20 beamline, has 72 spherical analysers installed with curvature radius of 1m (Figure 1).

F1 - Raman spectrometer - Synchrotron - Sil'Tronix - ESRF.jpg

The Crystal Analyser Laboratory (CAL) at the ESRF manufactures essentially 3 types of spherical analysers (bent, bent-diced or diced).  The different types of analysers are meant to satisfy the various experimental conditions required by our scientists in term of energy resolution, intensity and collected solid angle. The typical diameter of the spherical glass substrate is 100 mm and the curvature radius varies from 0.5 m to 10 m. More details about the three types of analysers:

  1. Bent analyser (Figure 2):  Consists of a thin wafer (~ 200 microns) bonded on a spherical concave glass substrate by the anodic bonding technique. This analyser crystal is utilized for spectroscopic studies that require a medium energy resolution (0.4 to 1 eV).
  2. Bent-diced analyser: Same as the bent analyser but with some “stress-relieve” cuts. Here we have an improvement of the energy resolution (< 0.3 eV) and a better uniformity over the surface of the crystal.
  3. Diced analyser (Figure 3): Consists of thousands of pixels of Si crystal epoxy glued on a spherical concave glass substrate. All the pixels are well aligned and have the characteristics of perfect flat crystal (no stress). Typical pixel size is ~ 0.8 mm x 0.8 mm x 2.7 mm. This analyser is utilized for spectroscopic studies that require a very high energy resolution (down to 1 mev).

F2 - Si(110) spherical analyser crystal - Synchrotron - Sil'Tronix - ESRF.jpg

The only elements coming from an external company are the double-side polished wafers (Ø 100 mm diam. and 3 mm thick). All the other operations are performed in the CAL laboratory. The required double-side polished wafers in Si (Ge) are provided by the Sil’tronix Silicon Technologies Company. These wafers are then processed by a grinding machine and a dicing machine. The grinding machine reduces the wafer thickness and prepares the wafer for the bent analyser manufacture and the dicing machine is used for preparing wafers for diced analysers manufacturing.

The typical production of the CAL is roughly 100 analyser crystals per year. These analysers are not only used at ESRF beamlines but also at other synchrotrons, facilities and universities worldwide.

F3 - Diced Si(951) Spherical Analyser Crystal -Synchrotron - Sil'Tronix - ESRF.jpg


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