Simulations of experiments at modern light sources, such as optical laser laboratories, synchrotrons, and
free electron lasers, become increasingly important for the successful preparation, execution, and analysis of these
experiments investigating ever more complex physical systems, e.g. biomolecules, complex materials, and ultra–short
lived states of matter at extreme conditions. We have implemented a platform for complete start–to–end simulations
of various types of photon science experiments, tracking the radiation from the source through the beam transport
optics to the sample or target under investigation, its interaction with and scattering from the sample, and registration
in a photon detector. This tool allows researchers and facility operators to simulate their experiments and instruments
under real life conditions, identify promising and unattainable regions of the parameter space and ultimately make
better use of valuable beamtime. In this paper, we present an overview about status and future development of the
simulation platform and discuss three applications: 1.) Single–particle imaging of biomolecules using x–ray free
electron lasers and optimization of x–ray pulse properties, 2.) x–ray scattering diagnostics of hot dense plasmas in
high power laser–matter interaction and identification of plasma instabilities, and 3.) x–ray absorption spectroscopy
in warm dense matter created by high energy laser–matter interaction and pulse shape optimization for low–isentrope
Simple analytic equation is deduced to explain new physical phenomenon detected experimentally: growth of nano-dots (40–55 nm diameter, 8–13 nm height, 9.4 dots/μm2 surface density) on the grazing incidence mirror surface under the three years irradiation by the free electron laser FLASH (5–45 nm wavelength, 3 degrees grazing incidence angle). The growth model is based on the assumption that the growth of nano-dots is caused by polymerization of incoming hydrocarbon molecules under the action of incident photons directly or photoelectrons knocked out from a mirror surface. The key feature of our approach consists in that we take into account the radiation intensity variation nearby a mirror surface in an explicit form, because the polymerization probability is proportional to it. We demonstrate that the simple analytic approach allows to explain all phenomena observed in experiment and to predict new effects. In particular, we show that the nano-dots growth depends crucially on the grazing angle of incoming beam and its intensity: growth of nano-dots is observed in the limited from above and below intervals of the grazing angle and the radiation intensity. Decrease in the grazing angle by 1 degree only (from 3 to 2 degree) may result in a strong suppression of nanodots growth and their total disappearing. Similarly, decrease in the radiation intensity by several times (replacement of free electron laser by synchrotron) results also in disappearing of nano-dots growth.
The presence of errors in tomographic image may lead to misdiagnosis when computed tomography (CT) is used in medicine, or the wrong decision about parameters of technological processes when CT is used in the industrial applications. Two main reasons produce these errors. First, the errors occur on the step corresponding to the measurement, e.g. incorrect calibration and estimation of geometric parameters of the set-up. The second reason is the nature of the tomography reconstruction step. At the stage a mathematical model to calculate the projection data is created. Applied optimization and regularization methods along with their numerical implementations of the method chosen have their own specific errors. Nowadays, a lot of research teams try to analyze these errors and construct the relations between error sources. In this paper, we do not analyze the nature of the final error, but present a new approach for the calculation of its distribution in the reconstructed volume. We hope that the visualization of the error distribution will allow experts to clarify the medical report impression or expert summary given by them after analyzing of CT results. To illustrate the efficiency of the proposed approach we present both the simulation and real data processing results.
Obtaining high quality images from Computed Tomography (CT) is important for correct image interpretation. In this paper, we propose novel procedures that can be used for a quantitative description of the degree of artifact expressiveness in CT images, and show that the use of this type of metric allows to assess the dynamics of image degradation. We perform different image reconstruction tests in order to analyse our approach, and the obtained results confirm the usefulness of the proposed method. We conclude that the use of the proposed estimates allows moving from image quality assessment based on visual scoring to a quantitative approach and consequently to support a CT setup providing high quality reconstructed images obtained by appropriate changes of the reconstruction parameters or algorithms.
The artifacts (known as metal-like artifacts) arising from incorrect reconstruction may obscure or simulate pathology in medical applications, hide or mimic cracks and cavities in the scanned objects in industrial tomographic scans. One of the main reasons caused such artifacts is photon starvation on the rays which go through highly absorbing regions. We indroduce a way to suppress such artifacts in the reconstructions using soft penalty mimicing linear inequalities on the photon starved rays. An efficient algorithm to use such information is provided and the effect of those inequalities on the reconstruction quality is studied.
For the High Energy Density (HED) experiment  at the European XFEL  an x-ray split- and delay-unit (SDU) is
built covering photon energies from 5 keV up to 20 keV . This SDU will enable time-resolved x-ray pump / x-ray
probe experiments [4,5] as well as sequential diffractive imaging  on a femtosecond to picosecond time scale.
Further, direct measurements of the temporal coherence properties will be possible by making use of a linear
autocorrelation [7,8]. The set-up is based on geometric wavefront beam splitting, which has successfully been
implemented at an autocorrelator at FLASH . The x-ray FEL pulses are split by a sharp edge of a silicon mirror
coated with multilayers. Both partial beams will then pass variable delay lines. For different photon energies the angle
of incidence onto the multilayer mirrors will be adjusted in order to match the Bragg condition. For a photon energy of
hν = 20 keV a grazing angle of θ = 0.57° has to be set, which results in a footprint of the beam (6σ) on the mirror of
l = 98 mm. At this photon energy the reflectance of a Mo/B4C multi layer coating with a multilayer period of d = 3.2 nm
and N = 200 layers amounts to R = 0.92. In order to enhance the maximum transmission for photon energies of hν = 8
keV and below, a Ni/B4C multilayer coating can be applied beside the Mo/B4C coating for this spectral region. Because
of the different incidence angles, the path lengths of the beams will differ as a function of wavelength. Hence, maximum
delays between +/- 2.5 ps at hν = 20 keV and up to +/- 23 ps at hν = 5 keV will be possible.
Here we report work done toward detection and characterization of micro-and nano-structures in bitumen, including
mineral particles-clay and sand as well as metal-organic micro-and nano-structures containing porphyrines. X-ray
micro-tomograph with monochromatic radiation has been used for detection of the structures. In order to detect and
characterize nano-and micro-structures tomograph’s operational wavelength has been tuned to absorption wavelength of “chemical element of interest” X-ray spectrum: whatever it is Si or porphyrine-forming metals like V, Ni, Co. Contrast between X-ray absorption of micro-structures containing specific element and average bitumen’s environment absorption provides a tool for measurement of element mass concentration as well as size and mass density distributions of micro-and nano structures not only on surface but in bitumen volume. Specifically the most interest is in measurement of vanadyl porphyrines and other metal containing chemicals in asphaltene micro-structures changing per asphalten concentration due to bitumen processing.
We present a new software project aimed at development of a novel and unique software environment, suited and
capable of solving a wide set of X-ray FEL optics problems. The complex of programs is based upon libraries of the
Synchrotron Radiation Workshop (SRW) package. The software can be used by XFEL experimental groups for
developing scientific instruments, planning experiments and processing experimental data. Specific examples of
applications of FEL wavefront propagation simulations are presented: modeling of edge radiation at the soft X-ray FEL
facility FLASH and of the wavefront propagation through grazing incidence optics of the hard X-ray beamlines of the
European XFEL. Possible ways for parallelization of calculations are also discussed.
The numeric simulations of multielement capillary lens' x-ray optical properties are presented, and x-ray experiments
with the lens are described. Using Cr Kα (0,229 nm) radiation and CCD-detector 11-time magnified images were