Abstract
Characterizing intense, focused x-ray free electron laser (FEL) pulses is crucial for their use in diffractive imaging. We describe how the distribution of average phase tilts and intensities on hard x-ray pulses with peak intensities of 10(21) W/m(2) can be retrieved from an ensemble of diffraction patterns produced by 70 nm-radius polystyrene spheres, in a manner that mimics wavefront sensors. Besides showing that an adaptive geometric correction may be necessary for diffraction data from randomly injected sample sources, our paper demonstrates the possibility of collecting statistics on structured pulses using only the diffraction patterns they generate and highlights the imperative to study its impact on single-particle diffractive imaging.
Highlights
Diffractive imaging experiments with x-ray free-electron lasers (FELs) aim to expose individual weakly scattering samples to a brief and intense focused x-ray pulse, scattering photons appreciably before the onset of radiation damage
Characterizing intense, focused x-ray free electron laser (FEL) pulses is crucial for their use in diffractive imaging
Besides showing that an adaptive geometric correction may be necessary for diffraction data from randomly injected sample sources, our paper demonstrates the possibility of collecting statistics on structured pulses using only the diffraction patterns they generate and highlights the imperative to study its impact on single-particle diffractive imaging
Summary
Diffractive imaging experiments with x-ray free-electron lasers (FELs) aim to expose individual weakly scattering samples to a brief and intense focused x-ray pulse, scattering photons appreciably before the onset of radiation damage. Description of technique This paper demonstrates how a diffractive imaging setup with randomly injected polystyrene spheres can be sensitive to the shape of an FEL pulse’s wavefront and its intensity profile even at peak intensities of 1021 W/m2 (exceeding 1.5 kJ/cm per pulse) Such measurements require little additional effort beyond routine calibration already performed to optimize sample injection. FEL pulse wavefront estimates on the extent of data correction necessary for samples that are injected into the same region of the stream of structured x-ray pulses (Fig. 1), without the need to infer this information from wavefront profiles collected using conventional sensors if they become available for x-ray FELs. we only require a sample change in the aerosol injector without breaking the high-vacuum in the experiment chamber to insert additional diagnostic instruments. The character of the average FEL pulse can be reconstructed when many single sphere measurements are combined
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