scholarly journals Crystallographic data processing for free-electron laser sources

2013 ◽  
Vol 69 (7) ◽  
pp. 1231-1240 ◽  
Author(s):  
Thomas A. White ◽  
Anton Barty ◽  
Francesco Stellato ◽  
James M. Holton ◽  
Richard A. Kirian ◽  
...  
Keyword(s):  
Free Electron ◽  
Free Electron Laser ◽  
Incident Beam ◽  
Crystallographic Analysis ◽  
Monte Carlo Integration ◽  
Laser Source ◽  
Integration Scheme ◽  
X Rays ◽  
Laser Sources ◽  
Serial Crystallography

A processing pipeline for diffraction data acquired using the `serial crystallography' methodology with a free-electron laser source is described with reference to the crystallographic analysis suiteCrystFELand the pre-processing programCheetah. A detailed analysis of the nature and impact of indexing ambiguities is presented. Simulations of the Monte Carlo integration scheme, which accounts for the partially recorded nature of the diffraction intensities, are presented and show that the integration of partial reflections could be made to converge more quickly if the bandwidth of the X-rays were to be increased by a small amount or if a slight convergence angle were introduced into the incident beam.

STUDY OF TRANSVERSE EFFECTS IN THE PRODUCTION OF X-RAYS WITH A FREE-ELECTRON LASER BASED ON AN OPTICAL UNDULATOR

2007 ◽  
Vol 22 (23) ◽  
pp. 4270-4279
Author(s):  
A. BACCI ◽  
C. MAROLI ◽  
V. PETRILLO ◽  
L. SERAFNI ◽  
M. FERRARIO
Keyword(s):  
Electron Beam ◽  
Free Electron ◽  
Free Electron Laser ◽  
Laser Energy ◽  
Laser Pulses ◽  
Collective Effects ◽  
Laser Source ◽  
X Rays ◽  
X Ray ◽  
Back Scattering

The interaction between high-brilliance electron beams and counter-propagating laser pulses produces X rays via Thomson back-scattering. If the laser source is long and intense enough, the electrons of the beam can bunch and a regime of collective effects can establish. In this case of dominating collective effects, the FEL instability can develop and the system behaves like a free-electron laser based on an optical undulator. Coherent X-rays can be irradiated, with a bandwidth very much thinner than that of the corresponding incoherent emission. The emittance of the electron beam and the distribution of the laser energy are the principal quantities that limit the growth of the X-ray signal. In this work we analyse with a 3-D code the transverse effects in the emission produced by a relativistic electron beam when it is under the action of an optical laser pulse and the X-ray spectra obtained. The scalings typical of the optical wiggler, characterized by very short gain lengths and overall time durations of the process make possible considerable emission also with emittance of the order of 1mm mrad.

scholarly journals XFEL diffraction: developing processing methods to optimize data quality

2015 ◽  
Vol 22 (2) ◽  
pp. 239-248 ◽  
Author(s):  
Nicholas K. Sauter
Keyword(s):  
Approximate Model ◽  
Difficult Problem ◽  
Integration Step ◽  
X Rays ◽  
Experimental Conditions ◽  
Structural Details ◽  
Laser Sources ◽  
Serial Crystallography ◽  
Difference Fourier ◽  
Damage Processes

Serial crystallography, using either femtosecond X-ray pulses from free-electron laser sources or short synchrotron-radiation exposures, has the potential to reveal metalloprotein structural details while minimizing damage processes. However, deriving a self-consistent set of Bragg intensities from numerous still-crystal exposures remains a difficult problem, with optimal protocols likely to be quite different from those well established for rotation photography. Here several data processing issues unique to serial crystallography are examined. It is found that the limiting resolution differs for each shot, an effect that is likely to be due to both the sample heterogeneity and pulse-to-pulse variation in experimental conditions. Shots with lower resolution limits produce lower-quality models for predicting Bragg spot positions during the integration step. Also, still shots by their nature record only partial measurements of the Bragg intensity. An approximate model that corrects to the full-spot equivalent (with the simplifying assumption that the X-rays are monochromatic) brings the distribution of intensities closer to that expected from an ideal crystal, and improves the sharpness of anomalous difference Fourier peaks indicating metal positions.

Laser-driven compact free electron laser: from extreme ultraviolet radiation to x-rays

2021 ◽  
Author(s):  
Alexander Molodozhentsev ◽  
Konstantin Kruchinin ◽  
Gabriele M. Grittani ◽  
Tyler Green ◽  
Jaroslav Nejdl ◽  
...  
Keyword(s):  
Ultraviolet Radiation ◽  
Free Electron ◽  
Free Electron Laser ◽  
Extreme Ultraviolet ◽  
X Rays ◽  
Extreme Ultraviolet Radiation
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