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News | 07-07-2025

Advancing Time-Resolved X-ray Science: Hadamard Timing and the WaveGate Pulse Picker

An international team of researchers around IKZ scientist Dr. Peter Gaal has demonstrated a novel approach to time-resolved X-ray diffraction, combining advanced Hadamard timing schemes with a novel device called the WaveGate pulse picker. This innovation enhances the ability to observe ultrafast structural dynamics in materials, offering new insights into processes that occur on microsecond and nanosecond timescales.

Illustration of the position measurement of a moving target: a long illumination suffers from a motion blur and cannot recover the position precisely (upper); a short illumination retrieves the position accurately (lower). Exemplary detector images: the overview depicts sections of 6 different Devy-Scherrer rings diffracted from the powder sample. The zoom shows the illumination structure of the encoded pulse pattern.

 

At the heart of this advancement lies the Hadamard transform - a mathematical technique traditionally used in spectroscopy and imaging. The researchers adapted this method to the time domain, enabling the encoding of X-ray probe pulses into complex, patterned sequences. These sequences allow for the reconstruction of a sample’s transient response with high temporal resolution and improved signal-to-noise ratio, even when using fewer photons.

To implement this sophisticated timing control, the team deployed the WaveGate pulse picker. This solid-state device uses a controlled deformation of piezoelectric crystals to diffract X-ray pulses with nanosecond precision. By synchronizing the WaveGate with the X-ray source and by using external triggers, researchers can generate customizable pulse patterns that follow Hadamard matrices—mathematical constructs that ensure efficient and accurate data acquisition.

The benefits of this approach were demonstrated in two test measurements at the PETRA III synchrotron in Hamburg. In one, the team tracked the motion of a translation stage using Debye-Scherrer diffraction, successfully reconstructing its position over time despite motion blur. In another, they monitored the micromechanical oscillation of a thin silicon nitride membrane excited by nanosecond lang laser pulses. The Hadamard method enabled the detection of subtle structural changes that would have been missed using conventional pump-probe techniques.

The WaveGate pulse picker, which enables the generation of Hadamard-encoded X-ray pulse sequences, was developed by the IKZ - Desy start-up TXproducts. Together with IKZ and DESY, a research center of the Helmholtz Association, TXproducts operates a test and demonstration facility for the development of novel X-ray photonics components. The facility will be used by IKZ researchers for time-resolved material science studies.

 

Contact

Leibniz-Institut für Kristallzüchtung (IKZ)
Crystalline Materials for Photonics
Group X-Ray Optics
Dr. Peter Gaal
Phone +49 (0) 30 / 246 499 614
Email peter.gaalikz-berlin.de

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