Russian-German Nanodiffraction Beamline P23
The new Russian-German nanodiffraction beamline P23 is designed for investigation of nanostructured and low-dimensional systems by the means of X-ray diffraction and accompanying techniques.
The 2m long spectroscopy type undulator in a high-β section provides photons in the core energy range from 5 keV to 35 keV. Higher energies are also possible, with some limitations for focusing capabilities. A special design of the magnet system allows suppressing harmonics by switching the undulator to a quasi-periodic mode. The LN2-cooled double Si-crystal monochromator has two pairs of Si(111) and Si(311) crystals. The mirror system serves both for harmonics rejection and beam collimation. Focusing can be done by 2 groups of 2-dimensional beryllium lenses. The first group in the optics hutch can provide moderate 2:1 focusing on the sample. The second group on the optical table in the experimental hutch can have a distance to the sample in the range of 0.5m to 3 m, thus providing spot sizes under 1 μm in the full range of photon energies. By combining the lens groups, one can achieve very high photon fluxes at the cost of a moderate beam spot inflation.
The beamline is equipped with a custom designed 5+2 circle diffractometer that can be operated in 2 modes:
- a large size Eulerian cradle setup with 140 mm space from the sample table to the beam, ready to accommodate samples cell weights up to 15 kg
- a heavy load setup with a hexapod mounted onto a goniometer, ready to carry up to 150 kg sample cells. The rotation axis of the goniometer is vertical, but can be inclined up to 5 degrees to enable surface scattering techniques for bulky sample environments
In 2018, we plan to build up the basic equipment pool that will include a low vibration He-cooled flow cryostat and a laser driven furnace. A standard Anton Paar oven can be provided upon request. A high resolution optical spectrometer for luminescence signal detection is mounted to the Eulerian cradle to combine high-resolution X-ray diffraction (XRD) with X-ray excited optical luminescence (XEOL). The X-ray detectors will include a state of the art LAMBDA pixel detector with GaAs sensor and a frame rate up to 2 kHz, avalanche diodes for fast time-resolved measurements and silicon drift diode for registration of the secondary X-ray emission.
As a further development, we also prepare an upgrade of the available prototype pulsed laser deposition apparatus to obtain a full-scale in situ growth environment.