The Crystallography Endstation at Beamline P11 at PETRA III

Abstract

Beamline P11 at PETRA III is dedicated to imaging anddiffraction experiments of biological samples. Thebeamline provides two experimental endstations: anX-ray microscope and a crystallography experiment.The P11 X-ray optics consist of a LN2 cooled doublecrystal monochromator and two horizontal deflectingand one vertical deflecting X-ray mirrors. The mirrorsare dynamically bendable and are used to generate anintermediate focus at 65.5 m from the source with a sizeof 16 × 96 μm2 rms (v × h).The crystallography endstation is installed on top of a 8meter long granite block which is the key element of theP11 experimental hutch. The sample position is locatedat 72.9 m from the source. A CVD diamond basedX-ray feedback system provides a long term beamposition stability of better than 1 μm. Thecrystallography experiment is equipped with a highprecision single axis goniometer with a combinedsphere of confusion of smaller than 100 nm. Theinstrument provides an on-axis microscope for easycrystal centering and beam alignment. Diffractionexperiments can be performed at energies between4 and 30 keV. The beamsize can be adjusted between6 × 12 μm2 FWHM (v × h) with a photon flux of about2 × 1012 ph/s and 300 × 300 μm2 FWHM (v × h) with1 × 1013 ph/s. Due to the very small beam divergenceP11 is ideally suited to measure large unit cell systems,such as viruses or large molecular complexes. Thebeamline is equipped with a Pilatus 6M-F detectorwhich allows fast data collection with frame rates of upto 25 Hz. In addition to the standard data collectionfeatures the beamline control software at P11 provides agrid scan capability for crystal centering andmeasurement of micro crystals (with and without crystalrotation) and an interface for serial crystallography. Anautomatic sample changer is under construction and willbe available to users in 2014. The robot will be able tomount samples within 10 s and the large dewar willallow storage of more than 300 samples