MS02-P13 Collecting best data for meaningful structures Andreas Förster (DECTRIS Ltd., , Switzerland) Claudio Klein (marXperts GmbH, , Germany) Clemens Schulze-Briese (, DECTRIS Ltd., Switzerland)email: andreas.foerster@dectris.comData collection is the last experimental step in a crystallographic project. All subsequent procedures (phasing, model building, model refinement) critically depend on the quality of the collected data. No amount of computational wizardry will turn poor data into a great model that can provide reliable biological insight.
With their intrinsic lack of noise, high dynamic range, small point spread and fast frame rates, modern Hybrid Photon Counting (HPC) detectors like PILATUS3 and EIGER enable the collection of data of exceptional quality. To fully exploit the power of these detectors, the user has to design her collection strategy based on the underlying technology.
In this presentation, we will explain why HPC data should always be collected with a small crystal oscillation increment per image (relative to the crystal mosaicity). This strategy is known as fine phi-slicing. We will also explain why HPC technology favors high multiplicity experiments. Native SAD structures determined at room temperature and from a crystal in space group P1 will illustrate the power of these two approaches.
Small oscillation increments minimize the background measured with each reflection, thus increasing signal to noise. High multiplicity decreases the systematic errors of the experiment and brings integrated intensities closer to the real value. Both strategies have long been known in theory to lead to the most accurate data possible. In practice, technological hurdles like detector readout noise and dark current and detector readout time have forced the user into compromises in the past, balancing what's best for the crystal with the constraints of the detector.
With HPC detectors, everyone can collect data optimally. This doesn't mean every experiment is a success. It still has be set up right. Keeping the points in this presentation in mind, trained crystallographers will not have to think twice to get the most from their crystals.

Keywords: Accurate data, Experimental strategy, Hybrid Photon Counting