Prospects for direct electron detectors in ultrafast electron diffraction and scattering experiments
Laurenz Kremeyer1, David Cai1, Malik Lahlou1
1Department of Physics, Centre for the Physics of Materials, McGill University, Montreal, Québec H3A 2T8, Canada.
Structural Dynamics (Melville, N.Y.)
|July 23, 2026
Summary
Hybrid pixel counting detectors (HPCDs) show significant count losses in ultrafast electron scattering experiments, saturating above ~2 electrons per pixel per pulse. This necessitates novel data handling and detector adaptation for advanced dynamic structural studies.
Area of Science:
- Materials Science
- Physics
- Chemistry
Background:
- Ultrafast electron scattering (UED(S)) experiments probe dynamic structural changes in materials.
- Hybrid pixel counting detectors (HPCDs) offer high sensitivity and low noise for UED(S).
- HPCDs are known to experience count losses at high electron fluxes.
Purpose of the Study:
- To investigate count losses in HPCDs under ultrafast pulsed electron beam conditions.
- To determine the saturation limits of HPCDs in pulsed UED(S) experiments.
- To develop strategies for optimizing data acquisition and analysis with HPCDs in UED(S).
Main Methods:
- Performed ultrafast electron diffraction and phonon-diffuse scattering experiments using HPCDs.
- Quantified count losses and saturation effects as a function of electron flux per pulse.
- Developed and validated normalization strategies and a model for measurement uncertainties.
- Tested HPCDs with ultrashort electron pulse exposures.
Main Results:
- Count losses are significantly worse in pulsed UED(S) compared to continuous wave (CW) applications.
- HPCDs saturate at approximately 2 electrons per pixel per pulse.
- The count-rate limitation restricts electron bunch charge for single crystal studies.
- Developed normalization strategies improve signal-to-noise ratio.
Conclusions:
- HPCDs require specialized data handling for ultrafast pulsed electron scattering.
- Saturation limits pose a significant challenge for current HPCDs in high-flux UED(S) experiments.
- Further adaptation of HPCDs is needed for optimal performance in ultrashort pulsed beam applications.
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