Detectors

Highly brilliant X-ray beams generated by synchrotrons and free electron lasers allow for high-quality structure analyses of crystalline materials by means of diffraction techniques. However, a variety of experiments is limited due to the insufficient performance of conventional X-ray detectors. A new class of semiconductor radiation detectors is the pn-junction charge coupled device (pnCCD) which, for the first time, provides 4D information about X-ray photons based on simultaneous 2D position, energy and time resolution

Reference:

S. Send, A. Abboud, R. Hartmann, M. Huth, W. Leitenberger, N. Pashniak, J. Schmidt, L. Strüder, U. Pietsch: “Characterization of a pnCCD for applications with synchrotron radiation”, Nucl. Instr. Meth. A 711 (2013), 132-142 Journal article

Improvement of position resolution

High-resolution X-ray diffraction studies rely on an excellent position resolution of recorded photons. In case of the pnCCD, the spatial resolution is limited by the quadratic pixel size of 75x75µm². However, as a consequence of charge sharing effects between adjacent pixels, a more accurate position determination is possible. We developed a new center-of-gravity method for analyzing the charge cloud size of individual photon hits for different X-ray energies. In this way, the position resolution of the pnCCD could be improved to less than 3µm.

Reference:

A. Abboud, S. Send, N. Pashniak, W. Leitenberger, S. Ihle, M. Huth, R. Hartmann, L. Strüder, U. Pietsch: “Sub-pixel resolution of a pnCCD for X-ray white beam applications”, J. Instr. 8 (2013), P05005 Journal article

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Energy-dispersive Laue diffraction

The spectroscopic performance of pnCCDs can be exploited to study the crystalline quality of the sample. Especially in macromolecular crystallography, the structures of new proteins are of interest. Using a pnCCD, the desired structural information is obtained from a single X-ray shot with white synchrotron radiation in an energy-dispersive Laue diffraction experiment. Recently, we could demonstrate that also for polycrystalline materials, a unit-cell determination is possible without a priori information about the sample.

Reference:

S. Send, M. v. Kozierowski, T. Panzner, S. Gorfman, K. Nurdan, A. H. Walenta, U. Pietsch, W. Leitenberger, R. Hartmann, L. Strüder, “Energy-dispersive Laue diffraction by means of a frame-store pnCCD”, J. Appl. Cryst. 42 (2009), 1139-1146 Journal article

S. Send, A. Abboud, W. Leitenberger, M. S. Weiss, R. Hartmann, L. Strüder, U. Pietsch, “Analysis of polycrystallinity in hen egg-white lysozyme using a pnCCD”, J. Appl. Cryst. 45 (2012), 517-522 Journal article

A 3D measurement of silver behanate using white X-rays and a pnCCD (Movie)

Aktualisiert via XIMS am 27.6.2014 von D. Bahrami