beamline description

Experimental station

At Xpress, we routinely run high-pressure diffraction experiments using diamond anvil cell (DAC). We have hosted different types of DACs at our sample stage. Our beam-size is 80 microns diameter which limits the typical pressure range as 0-50 GPa. High-pressure diffraction measurements at variable temperature is also feasible (using a closed cycle He cryostat or high-temperature using resistive heating in a high-temperature vacuum-chamber). Contact beamline team for information on experimental possiblities.

A PILATUS3 S 6M detector is used to collect the diffraction pattern. Detector is placed in a stage with a precise linear movement control permetting an easy control over the sample to detector distance.

Elettra is currently undertaking an upgrade program, Elettra 2.0, to reach an even brighter source. The PILATUS3 S 6M detector is available under this project, with following key features:

* direct detection of X-rays; single-photon counting;

* excellent signal-to-noise ration and very high dynamic range;

* short readout time and high frame rates;

* shutterless operation; and

* modular detectors enabling multi-module detectors with large active area.

These advantages permit not only reducing significantly the HP diffraction data collection time, but also increasing the Q-range and the data quality compared to the previous MAR345 detector.

Currently preference is given to those users who are ready to bring their own DAC and manage the sample loading in the DAC.

$End station$

$End station$

End station

High Pressure Support Facilities

Two Zeiss (Discovery V20) microscopes are available for the DAC loading.

For the gasket hole drilling a Boehler microDriller (Almax easyLab) is available.

A PACE5000 membrane pressure controller (max. He pressure 150 bar) is available with quick fit connector and/or screw-nut connector for 1/16" capillary for membrane driven DACs.

A BETSA PRL set up is fixed to the experimental table for monitoring the pressure through ruby and/or Sm:SrB₄O₇ fluorescence.

$MicroDriller$

Beamline optics layout

Source

A multipole superconducting wiggler (SCW) is the source of the Xpress beamline. This source is shared with the XRD2 beamline.

A factor of 3 (14) higher flux will be obtained from SCW compared to the permanent magnet wiggler of the already present diffraction beamline (XRD1) at 12.5 keV (25 keV). The SCW also result in a smaller source size due to the shorter wiggler length (1.4 m instead of 4.5 m). The detailed design and manufacture of the SCW has been done at the Budker Institute of Nuclear Physics, Novosibirsk. An upgrade of the original cold-bore design (with internal 20 K copper liner to efficiently absorb the thermal load from scattered photons and r.f. heating) has been done in order to reduce the liquid He consumption. The SCW has been reinstalled in July 2013 and is currently in routine operation.
The main parameters of the SCW are given in the table below:

Period length	64 mm
Peak field	3.5 T
Total no. of poles	49
Pole sequence	1/4, -3/4, 1, -1... ....1, -3/4, 1/4
Internal aperture	81 mm (H) x 10.7 mm (V)
Total powder	18.3 kW

Optical elements

A silicon crystal (flat monochromator) hosted in the splitter chamber in the FrontEnd section of the XRD2 and Xpress - intercepts the beam from the source and direct it to the focussing mirror at fixed energy of 25 keV. The monochromator is composed of a single slab of Si with surface cut along (111) direction and cooled to LN₂temperature by a cryocooler.

The Focussing mirror is a 1.4 m long torus, Pt coated to achieve 80% reflectivity at 25 keV and 2.9 mrad grazing angle.

Last Updated on Friday, 02 September 2022 20:05