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Updated: Sep 25, 2026

Measurement of X-ray Beam Coherence along Multiple Directions Using 2-D Checkerboard Phase Grating
Published on: October 11, 2016
Recursive direct phasing with reference-beam diffraction
1Cornell High Energy Synchrotron Souce (CHESS) and Department of Materials Science and Engineering, Cornell University, USA. qs11@cornell.edu
Abstract:
The reference-beam diffraction technique provides a practical way to measure a large number of triplet phases in a standard oscillating-crystal diffraction experiment for protein crystals. The triplet-phase data set from such reference-beam measurements contains a unique phase-occurrence pattern that leads to a new recursive phasing algorithm for the individual structure-factor phases. Application of the new algorithm is demonstrated for tetragonal lysozyme using 7360 triplet phases measured in a reference-beam experiment with a median phase discrepancy of 45 degrees. An electron-density map obtained using this phasing algorithm and the measured triplet phases shows good agreement with the known protein structure.
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