Beamline setup

Microdiffractometer

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ID29 is equipped with a microdiffractometer (MD2), driven by PMAC electronics. The MD2 has a set of five beam defining apertures which allows to change very quickly the beam size at the sample position. Aperture sizes are 75 (full beam), 50, 30, 20 and 10 microns in diameter. An additional beam cleaning aperture at the end of the collimator reduces scattering.

A MiniKappa goniometer is permanently available to reorient the crystal for different purposes (measure of cuspids, smart spot separation for large cells, measure of Friedel's pairs on the same image).

Beam sizes and photon flux

ID29 beam is permanently focused at 40x30 um² FWHM with an elliptical beam profile.

 

75um.png (75um aperture)50um.png (50um aperture)30um.png (30um aperture)20um.png (20um aperture)10um.png (10um aperture)

 

The 75 um aperture delivers a full beam, the 50um a 50x30 um² with sharper tails, the 30 um a round 30x30 um², 20 um a 20x20 um² and 10 um a 10x10 um².

Since the beam is collimated and the flux density is constant, a smaller beam delivers a lower photon flux. The measured photon flux over the whole energy range for each beam size is shown in figure.

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PILATUS 6M-F

The Pilatus 6M-F is installed on ID23-1 and ID29

The Pilatus 6M-F detector, which is installed on ID23-1 and ID29 beamlines, has an active area of 424 x 435 mm2 (2463 x 2527 pixels, which are 172 microns in size).

 

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The readout time per frame is 3ms and the maximum speed is 25Hz. In this way 25 images per second are collected while operating in shutterless mode, allowing to collect a complete dataset in a few minutes.

Data quality is usually higher than the one collected on a CCD thanks to absence of readout noise, zero background counts, zero point spread and no shutter synchronization. Furthermore the 20bit dynamic range permits to collect high and low resolution pass at once.

How to collect the best data

In order to obtain higher data quality collect data in fine slicing (i.e. Oscillation range smaller than half of the estimated mosaicity). Usually an oscillation range of 0.1 degree is a good choice, in combination with low Transmission. It is recommended to use the Characterization in MXCuBE2 to obtain the best data collection plan, with adequate transmission, resolution and oscillation range.

Image visualisation

ALBULA VIEWER is a fast and easy-to-use program supplied by DECTRIS, that displays PILATUS and allows optimal visualization of your data. 

Diffraction images can be viewed with adxv (version 1.9.7 or superior) or MOSFLM (version 7.0.7 or superior) and iMOSFLM