Components for the X-ray radiometry beamline at BESSY II

Area of Science:

• X-ray optics and instrumentation
• Synchrotron radiation applications
• Materials science for radiation detection

Background:

• Development of advanced optical components is crucial for high-precision X-ray measurements.
• The Physikalisch-Technische Bundesanstalt (PTB) operates critical X-ray radiometry beamlines at BESSY II.
• Suppression of higher-order radiation is essential for accurate X-ray spectroscopy and metrology.

Purpose of the Study:

• To evaluate the performance of optical components for the PTB X-ray radiometry beamline at BESSY II.
• To determine the effectiveness of different mirror coatings in suppressing higher-order X-ray radiation.
• To assess the suitability of silicon monochromator crystals and their cooling systems under operational conditions.

Main Methods:

• Reflectometry measurements were performed on various mirror coatings.
• The capability of coatings to suppress higher-order radiation was calculated.
• Reflectance homogeneity of silicon (111) monochromator crystals was measured.
• A test was conducted at a superconducting wavelength shifter to evaluate crystal cooling.

Main Results:

• Magnesium fluoride (MgF2) coating demonstrated superior performance for suppressing higher-order radiation below 4 keV photon energy.
• Silicon (111) monochromator crystals exhibited excellent reflectance homogeneity (within +/-1%) at low photon energies (~2 keV).
• The tested cooling system successfully managed an absorbed power of 14 W for the first crystal.

Conclusions:

• MgF2 coatings are highly suitable for X-ray optics requiring suppression of higher-order radiation in the sub-4 keV range.
• Silicon (111) crystals provide stable and homogeneous performance for low-energy X-ray applications.
• The cooling infrastructure is adequate for the thermal loads anticipated in superconducting wavelength shifter setups.